Flight test and evaluation of Omega navigation for general aviation

Section 1 INTRODUCTION As the airspace becomes increasingly more congested in the next few decades, Omega navigation will provide a low cost means for general aviation to upgrade to area navigation capability. In .this analysis and evaluation, a commercially built low cost receiver was flight tested and compared with VORTAC results. Various observations, conclusions, and recommendations were then made upon the Omega system and low cost general aviation receiver use.

General aviation, as a portion of United States civil aviation, accounts for 98% of the civil aircraft fleet. Some 95% of civil pilots are general aviation airmen., and 96% of the airports are used primarily by general aviation. In addition, general aviation accounts for 37% of intercity air passengers, and virtually 100% of local passengers, (for a total of 90 million annual passengers), industrial aid flying,_ agricultural and forestry flying. It contributes to the • economy through export sales of $150 million and domestic of $1.5 billion annually (Reference: Flight Transport- sales ation Laboratory Report R73-5A).

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The_.•importance of general aviation has been demon- strated. As the air traffic environment becomes more heavily populated, the importance of the development of low cost area navigation becomes critical for general aviation.

. allows much more freedom in routing than tile.

Area navigation airway beacon system since it allows direct and offset course routing. There is a strong potential far Qmega navigation to provide low cost area navigation for general aviation.

Omega can enhance the VOR system by providing navigation coverage capability (since Omega is not light of sight limited) to areas where it is not cost effective to install.

VOR transmitters such as mountainous regions, remote inland areas and offshore fishing or drilling sites.

The irnplementation of any new navigation system requires real world tests during a complete range of environmental conditions. This. thesis ha made that eval- uation and found the candidate Omega ItZ1AV potential to be real but with certain practical problems which can be solved ..with continued development.

=.^a TEST OBJECTIVES AND SCOPE r, ^' The objectives of this test program were to determine ,^ is the suitability of low cost Omega for General Aviation use '- through analysis and evaluation. of flight tests designed to cover a broad spectrum of possible navigation effects and i differing flight environmentso The scope of these effects investigated during both VFR and IFR conditions included:.

noise and interference meas^a.rements at various altitudes; use of various station pair combinations and flights parallel to LOPS; detection of phase shifts due to diurnal ionospheric height variations, local coastline, terrain,.

maneuvers or local noise sources; and evaluation of ground versus airborne performance.

2.1 MIT/ASI Joint Test Effort The^NilT Flight . ^iransportation Laboratory and Aerospace Systems, Inc, (ASI) have completed a flight evaluation of a low cost Omega navigation receiver in a General Aviation aircraft. The results of the program provide both qualta- tve and quantitative data on the Omega Navigation System under actual operating conditions (Ref.. 1). These data

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directly support current NASA/FAA research programs° The joint flight evaluation program consisted of two r major parts corresponding to the ultimate application ^of the ^ ^' information obtained in each of two geographic areas, The Wallops flight program obtained Omega signal and phase data `^ in the Wallops area to provide preliminary technical information and experience in the same geographic area where NASA plans to evaluate the performance of a differential Om^:ga system. The Northeast Corridor flight program examined . Omega operational suitability and performance on the VTOL RNAV routes developed by ASI (Ref. 2) for city-center to city-center VTOL commercial operations in the Bostan-New York-tiJashington corr. idor .

2.2 Flight Test. Locations and Environments All the fli ht tests were conducted in three eneral g g areas: the Wallops area and Northeast Corridor as mentioned above in the joint MIT/ASI. test program, and also in the.

local Boston and northern 'New England areas. The flight.

environment included: day, night and transition. period operation; VFR and IFR operation;: clear air,, hazy, rain and snow shower. operation; : and with and without. VHF radios in use...

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i Section 3 OMEGA NAVIGATION SYSTEM ^'! This section includes a basic discussion of the ^, ^ ` y x?

Rj ^i principles of hyperbolic navigation, a brief description of r: ^, '^^ the International Omega Navigation System, a summary of some ,,; of its advantages and disadvantages, and discussion of the ''' future of the Omega system and its uses.

3.1 Principles of Hyperbolic Navigation Hyperbolic navigation is a radio navigation technique used by the Omega, Loran, and Decca navigation systemo It iS based on a distance difference measurement whereby the navigation receiver determines one or more lines of position along which the receiver is assumed to be located (Ref. 3)0 The intersection of two such lines of position is then the location of the receiver. The term "hyperbolic" refers to • of possible receiver locations having a constant the locus distance. difference between. two transmitter sites. In Figure 3-1, from any poin X, on the line of position, the difference between the distances to transmitter A and to transmitter B is constants

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n. X2 rBl s rAl t rA2 rB2 Transmitter B Transmitter A Line of Position (LOP) rA2 rB2 = rA1 — rBl =Constant } Figure 3-1 Line of Position determination The distance measurements are not made directly, how- ever. Instead, using the propagation speed of radio waves, time parameters of the received signal are measured relative to a local time standard, such as an oscillator; When two time parameters are. measured relative ^o the local standard.

and subtracted, they give a time difference, which varies from the distance difference by the speed of propagation, This time parameter can be the leading edge of the received.

signal, as in Loran., or it can be a phase measurement, as in Omega.

i _ .__ -- ^ . ^-___ ^ _ I _ _ _ _ A single position difference measurement defines a hyperbola called a Line of Position (LOP), but one hyperbola cannot specify position uniquely ° Two or mare sets of hyper- bolae or Lines of Position (LOPs) are requirEad as shown in Figure 3-2o Figure 3-3 illustrates the deleterious effects of poor LOP geometry wherein small errors in LOP determination can result in large errors of estimated position ° This occurs when the intersecting hyperbolae are at angles of less than 50° (Refs 4), Such^a condition drastica ly reduces the precision of position measttrer^er t .

^. '^, rnans^an iui v^._^ , Three Omega Transmissions are Needed to Figure 3-2 .

.

O Determine a Position Fix LOP A-C LOP A-B Station A _o Station B

_ ^ _---_-_ - , = 1 —

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Station C Example of Poor LOP Geometry for Figure '3'3 Position Fix tdavi.:gatiori System 3 0 2 International Omega Omega is a very low frequency (VLF), hyperbolic a navigation system designed for worldwide navigation coverage with eight transmitters, It utilizes phase measurement ;; differences to determine constant distance difference lines of position (LOPs)o Accuracies of one to two miles are achievable, but with position ambiguities occurring in ,;, ^.

multiples of lane width, However, these ambiguities. are ^^ ; ',

^1

,^, largely resolved by the use of multiple frequency receivers.

Eight .stations are planned, each with. l0 kw power, These stations, listei in Figure 3-4, transmit on frequencies of 10.2, 11.33, 1306 kHz and a unique communication frequency alternately. The: transmitted signals are sinusoidal with tight phase tolerances maintained by quadruple cesium standards. The only modulation is the cycling of the trans- mitter between frequencies, The signals travel in the wave- guide formed by the earth's surface and tine ionosphere, with attendant waveguide phenomena as illustrated by Figure 3-5.

As the height of the ionosphere varies diurnally, the speed of propagation varies, and so does the phase of the signal at the receiver as in Figure 3-6. Similar variations occur due to the various conductivities of the earth's surfaces: ice, water, and lande Another waveguide phenomenon is the presence of various modes of propagation near the transmitter, which makes each station unusable. within seven hundred miles of the transmitter (Refs ° 5 and 6).

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^I r I I^ .^ tl SEGMENTS A B C D E F G H I DURATION ( 0.9^( ^'; 1.0)^ 1.1 ^l 1.2 ^( 1.1 l( 0.9J^ 1.2 ^L 1.0 J) (SEC) ^ 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 v ii STATIONS ^ 10 SECONDS I ^( REPETITION INTERVAL NORWAY A 10.2 13.6 11,33 /ii// IIIIiiIII ^ 4^ TRINIDAD 10.2 13,6 11.33 III {^ ///// I I I I I I I I I L ^ HAWAII 10.2_ C 13.6 11.33 //// I i U l l l l NEW YORK D 10.2 13.6 11.33 iN pAKOTAi /...... ^^^^^^^ LA, REJNION E -10.7 13.6 11.33 ISLAND //// unuu ^! ARGEl11s INA F 10.2 13.6 11.33 !j /iiii_._ unnii ^, AUSTRALIA G 11.33 10 2 13 6 ^ /i 1111111 tl JAPAN H 10.2 13.6 11.33 ^iiii niuni Figure 3-4 Omega. Transmission Format N,GHT^SI~CTOR 1N AIRTH UT- ^μE O^ _^ LOWER BOUNDARY d ^^ ^^^ O F 9,^ _'\ ^ IONOSPHER ► EO W Av E V s ---- /2 "9 fiaST SURFACE tyq^ a3 '°9 ^ s`'°w ^1T F ^ OF EARTH ^^^^ .^ _ .

P^ a^ ^^ d = Great Circle Distance Between " ^ t^Q' Transmitter and .Receiver RECEIVER TRANSMITTER Figure 3- Earth-Ionosphere Waveguide 2h

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^ '^ ( I^ (IlII^ 'cOUIVALENT NIGHT ElfPO:^ENTIAL PROFILE i ^ .^-- ^ I I( 4 C ri -" ^ I ^-^- ^' ^ ^_1•-----^" AVERAGE NIGHT(Smoathed) I AVERAGE DAY

{Smoothed) 1 I j ' -t•- ' t

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I I (^, i I ^'' SOLAF FLARE

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I ^ ^ ! ^ ^I 1 I ^ , -e 10° 10° 10° 10' EFFECTIVE CONDUCTIVITY v, mhoslm

Figure 3- 6

Effective Ionospheric Conductivity Profiles

Distances. are derived from differential phase m%'asure-

ments, which have. an ambiguity cf one. cycle, Thus, when obtaining a position fix, the position estimate will be accurate to one or two miles but with an ambiguity of some multiple of eight mileso That is, the receiver cannot absolutely specify position over a distance greater than eight mileso For most appl,icat:ions, many measurements will be taken before the vehicle has traveled eight. miles, so the ambiguity pr<^blem is not severed Furthermore, because of .the Omega frequency selection, receivers utilizing frequencies 10.2 and 11..33 kHz observe ambiguities spaced approximately miles apart. This is accomplished by comparing 10.2 1cHz with 11.33, kHz zero phase crossings, i.e., every nine 10.2 kHz lanes or ten 11.33 kHz lanes, the eero crossings will coincide, as shown in Figure 3-7.

U I Sa O O O O ^ p O O O O O p O O O O O O O O O O O O O O © O O Q O O O O O O O O O O O O O O O p O O O O O O O O O O O O O O O O O O O O O O O O G O O O O O O O O ^ O .- _ 11.3 3 kI? z 10.2 kHz.

Figure 3-7 Ambiguity Resolution to 72 nm by Use of 10:2 kHz and. 11033 kHz Lanes Omega `System Advan ages and Disadvantages 3.3 As a navigation system, Omega. has both advantages and ds;3dvantages for the aviation usero The transmitted signals provide worldwide information. for area navigation (RNAV) with no line of sight limitations, and the errors of the system do not increase with time as do those in Doppler and inertial navigation systems, However, the Omega system by itself is not accurate enough for other than enroute navigation, and it has suffered introduction delays for economic, technical and political reasons.

Most enroute radio navigation in the United States is based on the Very high frequency Omnidirectional Radio Range (VOR) system which provides a standard for Omega evaluation, VOR signals provide bearing from the station sometimes augmented by Distance Measuring Equipment (DME) to supply sufficient information to drive an RNAV computero The " accuracy of VOR and DME is roughly 3° and .1 mile, respec- tivelyo However, the VOR/DIME system is strictly line of sight, which limits its low altitude coverage area as seen in Figure 3-8 (Ref, 2)o In addition, overall accuracy .decreases as distance from the station inc^,,^rases, and the f system user is confined to areas with usable signals, In contrast, Omega provides worldwide signal coverage at all altitudes because of the nature of the signals. Furthermore, Omega requires only eight stations for worldwide coverage, versus more than 600 operating VOR stations in the United States alone which provide only partial coverage.

° Rc,nfa^ fraAO o^2 _ usneL^ Navfcarlov slcr^ ^.

Q RcCcIVcO j] LOST ^ -".vi)0 ^ .' ^ ^ Q DIRECTIO^OF FLlG1-il'

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r' 1 ^ F- 1 ^ n ^ ^1{ N 3000 - 11 ^ ^ ^^ 3^^` ! 1 ^ ^y `^, ^ 2000 ^ . ,` ^'^ ^P^ 1 ^ / ^ ^^^' r ..^ ^o ^ , P 1 , ^ ^ ^OQ`^ J 000 ELEV ANGLE = 4.31 mr - t'`,.,,^^.,-^.;.; !

ANT EL.

' DOhIIfJANT' TERRAIN PROFILE : 267 .. ...

F 0 40 DiSTANGE FROM STATION, Nht Sample VORTAC Coverage, Madison VOR

^ Figure 3-8

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Another favorable aspect is that Omega accuracy can be increased. by various means, These include the use of ground y monitor stations to broadcast phase correction information (differential Omega), processors utilizing air data (rate aiding), sophisticated. filtering techniques, and . improved.

antennae (H field crossed loop instead of E field wire or rod)^(Refsa 7 and 8)o In addition to improving accuracy via differential Omega, micro Omega and alpha Omega which broad- cast localized correction information to the receiver, there are also composite and difference frequency Omega which use the differer..t frequencies from the transmitter to cancel out any phase anomalies which may occur along the propagation path (Refs a 9 and 10) .

Other advantages of the Omega system include its simple signal format, relatively simple handling of the signal permitting a usable CDI display and thus its potential for low cost airborne equipment, Due to the ranges from which transmitters are. received and the nearly linear nature of the LOPs, the CDI has a constant deviation sensit,^ity regardless.

of range to the user's origin or destination (Ref, ll).

The Omega system does have everal dis^.dvantages. Each of the eight stations is much more expensive than a VOR/DME ', I I I station, and present system accuracy is acceptable only for low accuracy operation (non precision approaches and enroute navigation). Omega. is also susceptible to atmosphere and locally-generated noises Moreover, at the present time, ..

station reliability is not sufficient for aviation use, although it is expected to improve steadilyo Diurnal propagation effects cause apparent shifts in the reference grid. Noise effects can become critical in heavy precipitationo A standard for resolution of lane ambiguity must be determinedo Precipitation .static and high frequency break through are problems common to the use of E-field wire antennas (Ref , 12) .

A definite user warning system is needed to indicate periods of polar Cap Absorption (PCA), Sudden Ionospheric Disturbance (SID}, and station outage (Ref. 11). PCAs are caused by solar proton showers usually only in the higher ;' lattitudes (55° to 90°)o They are predictable a short time in advance. but. the severity and length of activity are not, SIDs, somftmes called sudden phase anomalies (SPA), are caused by x-ray bursts (from solar flares) bombarding the â using both PCAs and ionosphere on the sunlit hemisphere..

'' ;, SIDs the received phase delay is decreased changing the 4c Y.

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,i• ^ ^.... _.. Y...: calculated position by up to 4 nm. and at the same time signal strength is enhanced (Ref. 13). An interim plan is given in Appendix C for the temporary information system while an .international standard is being chosen.

3.4 Future of Omega System and' 'ITses The future of the Omega Navigation System looks optimistic in the light of the above advantages and disad- vantages ° For every drawback there is at least one feasible proposed solution. Although Omega will not replace the VORTAC or Loran C systems, it will provide navigation cap- ability where these other systems cannot; for example, over the North Atlantic and unpopulated regions where it isn't cost effective to deploy LF or VIiF systems. It was recently concluded that Omega has a definite role in the fourth generation ATC system (Refs ° 5, 14) by providing general aviation and other low altitude airspace users with a continuous inexpensive RNAV capability ° Other uses for which Omega has been studied other than marine and submarine {for which it was originally designed) include: global rescue net- work (GRAN), windfitiding using balloon radio sordes,postioning systems for :mass transit (OPLE), guidance navigation for mini RPVs, as well as a variety of uses in hybrid form (Refs. 5, 8 and 15) ,

Section. 4 GENERAL AVIATION NAVIGATION REQUIREMENTS The term general aviation is an umbrella phrase which usually includes all aviation which is not military or air- line, and this can be anything from a Piper Cub to a Gulf- stream business jet or fram a traffic helicopter to an agricultural spray plane.

Reference 16 indicates that in spite of a recent slow- down in general aviation itinerant operations, the number of general aviation I^'R aircraft handled has continued to increase, and they are forecast to grow substantally.through- out the next ten yearso There has been an ever-increasing acceptance as well as requirement fox general aviation pilots to file IFR flight plans and use the FAA en route traffic control system. More pilots are becoming IFR qualified and more aircraft are being equipped witlL the necessary navigation and communication dear. Thy industry anticipates these trends will continue and by fiscal year 19II3 the volume ^f general aviation IFR aircraft handled is expected to reach 20.7 million. This if over five and a half times the present volumeo ,, r' 4.1 'Variety of Types and Requirements' of General- A viation ..__ ^x Aircraf t General aviation avionics navigation equipment requirements vary from nil to the latest in automated RNAV capability. General aviation is by far the greatest user of domestic airspace. Statistics. show that 98 percent of registered aircraft come under this category.and they condv^ct more than $0 percent of all domestic United States flights (Ref, 17). General aviation aircraft, not including business aircraft, are almost exclusively piston powered light planes, slow moving with severe payload and performance li*^itations (usually beloca 10,000 ft and slower than 250 kts), Weight, the cost of equipment and ease of operation are all important..

The navigation environment falls into two distinct areas, terminal and enroute, 2'he terminal area acts as the collecting hub for all the different. types of aircraft which greatly increases the risk of midair collisions, The enroute portion is where P.NAV has its greatest impact in increasing user freedom, safety and economy by allowing direct routing } (rather than via beacona) and offset paths parallel to congested airways. The ideal requirements for general t aviation are: for "automatic" receivers with lattitude and longitude read- . out ^^nd built in skywave corrections. There is also a good probability of the appearance of low cost automatic receivers derived from the current Air Force low cost competition (Refs. 20 and 21). Relatively good. accuracy (.2 - 2.0 nm) also may soon be available at low cost through composite Omega application (Ref. 22).

2 Comparison of VOR, Li^ran, and Dmega 4.

.There are four basic types of position-fixing methods .used by ground-based radio systems.. These. are intersecting lines of position determined by distance/bearing (rho-theta), bearing/bearing (theta-theta), distance/distance (rho-rho) and hyperbolic line of position measurements.

All .four of the techniques are used in modern radio aids, but their performance characteristics differ consider- ably. The four important types of errors are propagation, geometry, instrument, and dynamic. The propagation errors, are strongly dependent on operating frequency. Ground waves are primarily used at low frequencies and long ranges, because. they tend to follow the earth's. curvature, These waves are, however, susceptible to significant propagation P, anomalies because of changes in surface conductivity and ^C^INQ PAGE BLANK. NOT FII,MID ;, dielectric constant, as well as diurnal ionospheric effects.

The line-of-sight waves are used xn the VHF, UHF, and micro- wave regions and primarily for short-range use. In the lower of the bands, site errors due to reflections are a serious problem (Ref. 5).

The three primary performance parameters for comparison are. accuracy, coverage, and signal. availability. Of the candidate systems, Loran-C offers the highest. performance.

with respect to accuracy. The signal coverage and aval- ability of the VORTAC system are primarily affected by signal.

propagation characteristics. The line-of-sight limitations of the VHF/UHF signals of the VORTAC system can significantly decrease the signal availability in certain areas, The low frequency and very low frequency transmissions of Loran-C and Omega respectively are not limited by line-of-sight propagation; consequently, they can provide navigation .signals over a wider area and serve more diverse customers than the VORTAC systems In a cost-effectiveness assessment covering twenty years, the operations and maintenance costs predomi- Hate. over those of the initial facilities and equipment expenditures. The Omega system. requires the smallest number of ground station facilities followed by Loran-C, Differen=- tial Omega, and the various configurations of the VORTAC _'z i . _ i system. The Differential Omega system requires the lowest expenditure for facilities and equipment and also for the ` .operations and maintenance functions. Loran-C .and the various configurations of the VORTAC system follow in their respective order.(Refo 23).

In comparing user equipment, the Loran and Omega systems consist of an antenna, coupler, receiver-processor and indicator versus the VORTAC system of dual antennae, couplers, raw data displays, course line computer and RNAV display. ^h he latter system quite obviously becomes more expensive for comparable enroute accuracy. In addition, pilot workload for Loran or Omega systems can be reduced by at least 50 over VORTAC systems by eliminating the continuous changing of VHF . channels and three dimensional references associated with each VORTAC station. For single pilot operation, which is the case for the large majority of general aviation, this is of importance in alleviating fatigue and maintaining pilot awareness (Refs. 24 and 25)0 Comparison of VLF- and Omega 4.3 The International Omega System occupies the . VLF spec- tram between 10 kHz and l5 kHz, with . synchronized pulsed.

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continuous wave transmissions and communication. The U. S.

Navy also operates an additional set of VLF transmitters around the earth for communication and time dissemination between 15 kHz and 25 kHz, The latter group are authorized to transmit at power levels up to 1,000 kw, and the received signal strength of the communications stations is between 25 uv and 10 my varying with transmitter distances of 9,000 nm and 400 nm respectivelyo Omega power output, however, is authorized at only 10 kw and only North Dakota is currently near full power as shown in Table 4 -l. The received signal strength of the Omega stations varies from 15 uv to 400 uv for transmitter distances. of 3,000 nm and 1,200 nm respectivelyo Because strong VLF signals are normally available., clear-cut signal drop-out criteria are easily established, with the result that high confidence can be placed in the correctness of an acquired signal and data smoothing is unnecessary. Because the communication signals. are contn- uous wave there is a statistically higher probability of obtaining a correct fix once per lane than with the time sequenced Omega signals.

Radiated Power (kw) Frequency Station Location (kHz) (Nominal) (Authorized) 1,000 17.60 890 Cutler, Maine NAA 150 1,000 Balboa, Panama Canal Zone 24.00 NBA 250 1,000 Jim Breek, Washington State 18.60 NLK 23 .40 40 to 630 1,000 NPH Hawaii 1,260 1,000 22.30 NWC North West Cape, Australia 16.00 250 300 Rugby, Great Britain GSR 125 500 Yosami, Japan 17.4 NDT ^^ 150 35:0 JXN Nelgeland, Norway 16,4 21.4 500 l,OC10 HSS Annapolis 28.5 50 100 NAU Puerto Rico Norway 12.30 7 SSA 2 10 SIB Trinidav 12.00 10.2 12.20 + 11,33 5 10 S2C Hawaii North Dakota 9 to 10 10 S2D 12,85 13.E 5 10 SOH Japan 13.10 Table 4-1 Omega and VZF Communication Stations Available for Navigation ---_. 4 Omega navigation, on the other hand, is still in its development stage and can be expected to improve in signal strength, coverage, and nL^:mber of selectable stations. VLT^+' and. Omega are affected similarly by diurnal variations but only Omega has published skywave correction tableso Finally, Omega ^:.s a dedicated navigation system and planned station outages for maintenance are published in Notices to Mariners, whereas the Navy has not formulated any definite operating policy that guarantees continuous station operation (Ref. 26), +?

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Section 5 FLIGHT EQUIPMENT AND FACILITIES The equipment and facilities used to conduct the Flight Evaluation of Omega Navigation included a Mark III Omega Navigation System, a Mark III Custom Interface Unit (CIU) and data recorder,.. an exteral filter with. course deviation indicator and strip chart recorder, a voice data recorder, and the Piper Cherokee 180 test aircraft equipped with a C-band transponder° 5.1 Omega Mark III Navigation System The Omega avionics system used in the flight test program was the Omega Mark III Navigation System manufactured by the Dynell Electronics Corporation.of Melville, New York.

This avionics system described in Reference 27 transforms Omega phase data into crosstrack deviation and miles-to-go displays familiar to pilots. The sy^^tem consists of the twa units shown. in Figure 5-1, plus an antenna coupler. The DR-30 Receiver houses the majority of the electronics, and ...the front panel contains the switches to set the circuits for navigation. The. DI-30 indicator provides the readouts w used Suring flight as well as switches for setting miles-to- w go (MTG) and course number (CN) (a parameter describing _ F_ .

;r SENSITIVITY POT COURSE/ MILES/ ^''^ SYNC MODE SWITCH AUTO 21=80 SYhC SELECT 5^'^ITCH SWITCH ^ ^ LOP I ^\' ITCN ' tGNAL WEAK S `^ ^ b SELECT LIGHT SWITCH Q SYFJC--SEN — Li%P 1-- — YrC.Y^^C;T•,T— — — ^ CDI ^ __ coca ^ wacar--_ I f,^ILES D O (d = B D + O I .5 TO GO ccueeE G RCVO P.EFO HOLD® T^ ^k^ v°I^lo FInIs 13 5 I ^ CGUkSE A4ILES ^ V s nuro ^ SET SET r ^k, ZEfiO 0 I . ,^ ^ ^`a d D ^^ (^ ^,v,, rt`) >!

^ `-TO/ FRO:`k4 '^` —LO?2.--!'(l+YPdSNT-- — ^ FLAG ^- — OFF/Ofv/RES LOP 2 (^;ILES se•r S1`111•CH $ELECT" COiVTROL SWITCH ^ LOP 2 ADV/NOR/RTD COURSE SET 51'11TCH SYIITCH COt'1TROL RECEIVE(; INDICATOf; Figure 5-1 Omega Mark III Navigation System Components .^-^- _.

H ^ ^ k k _ ., .

flight course relative to the Omega LOPs. The pear f' power requirement is 1 amp at 12 V DC. An antenna coupler is ' provided so that the standard ADF sense antenna may be used simultaneously for Omega and^AD^'. A functional block diagram for the Mark III set (receiver and indicator) is shown in Figure 5-L. The basic system specifications are x shown in Table 5-l0 The range of the navigator is in excess of 1,000 miles .for a .single flight leg, but is unlimited if multiple way- points are used. The basic system accuracy is independent of the length of flight e^^cept when flying during transition without skywave corrections. Should a course deviaL-ion be encountered, simply re-zeroing the CDI will pro`^ide the pilot direct course to the original destination. Flight with a new plan changes may be made at any time by inserting the new destination and re-zeroing the CDIo The Mark III System is provided with a standard autopilot output which can be used in the same manner as that from a VOR system..

The receiver unit contains essential]_y three separable and distinct subsystemso These include clock generation and.

synchronization, phase tracking, and processing tQ compute crosstrack errors and distance-to-goo These three subsystems twat -.-- ,.-....- ^i : ^ r T E FIELD - "^ ANTENNA LL^ COUPLER ^ LOP 7 S; C_CTEO ST«i IQAS LOP i rte, SELECT ,.tom SM•17CHE5 (P-S)yl ^ PRE AMP LOPI (F-S)MI '^ ^ —_^8 C 1• 1 X3.7 LANL WIDE ACCUt2JLA70R IF-S)SI 9AND lP-S)51 PHASE TRACK VECTOR LOP., FILLER ERROq LOOP SELECTOR i, S°Li-CT "^ Sl "TRACTOR AND AFC AMP (P-5152 ( F- ^ : : TC.'-S S),z r L P Z -i^_--. ^T - L!M17ER - (_. ^.^^ AC^LML'LATOR TRERFORS NARROW (P'SIM2 ^"--^ :RAND • flLi ER.

SELECTED LOP ^ 5FL£:a EO STATIOKS STATION CROSS AMP ^• N DEViATlON • A70R tYEAK SL^iN . 1L iBCICA7OR.

S / N EST LL N Li41TER _': ^- } i^ ' :5 .^i 4:^!.ATCR `LEAK S!G LICt:T-^ sj^,s r. ^C ^ ;-`C^a..

°'r^ ^ "^^.-. C01 VOLTAo (VL^i ^ ^ _^ O^.F ^ :_^ SEaSITIV: TY ARI; HL1E7iC RCV RET I ADV REF , ADJUST LT ^ / HOLD tT ^T/F ^ CON: R^L (VTF' ^ ^^ URIT ENVELOPE '^'-` z ^ ^- I RESET fl -, r- C7 ^ OET ECTOR Q = b . ^.^ i^ ^ j { F-! w ^'"' 4Ji0-^LCJ C0.17S: I y Q' a ^ TfiR_SN c ^ COItTF.CL d:LE ; / CO` ITF OL I o ia:e-z:4o i c^^ ^° O ^ iHR£s^oLD `' _ ", ON •^.•^ SYNC '!.^ ^^ CLO C L K SLE'^ C04TROL ^ I COUFSE OENER«TOR ID^ I PULG,• ^:;^uiN t COURSE CpU ,: COURSE/;a1ES ESTIMATOR ^ ' + SET - SELCCT ^ 1 SYNC MODE SELECT SWITCH ^^ C1TA DECOD5R SL+EGT CLOG Y.OLO SYvc s-A-1e•t P UL`.E WiDiM ENABLE ^ CT SA7TCN / } ^'^ ^ ^ 6t:L1:S TO 00 ^ '`!

R'4^ :S _ L^r G_M1SRATOR R'.[:•}eyD A7C0 R-9 FLL9E SYSTEIR F3 E C04'al'- SC:LLATO(? -^{^ L M. JEH CLOCK GEH SELECT :. C:O1T -R=AGOUT O MILES ^ET GLOCY,': i0 '+YSTEM CLCC':.*: TO SY57EM A3 SLJC'IgEO ..5 flEOUtR ED Figure 5-2 Omega rSark III Navigation System Functional Block Diagram _ ^_^^.- ..,.,.

J ..

:: Table 5-1 Omega Mark III Navigation System Specifications ^; ^: i are briefly discussed belowo 5.1.1. Clock Generation and Synchronization The clock generation subsystem includes a stable oscillator from which the reference signal is derived for the phase tracking loop. and a commutator clock which matches the Omega transmission sequenced Synchronization of the receiver involves the aligning of this commutator clock with the received Omega signals which are detected and which operate the RCVR light on the receiver front panel. The SENSE GAIN potentiometer adjusts the threshold for this light and the pulse width gated The REF light is illuminated by the internal clock gate while tLie RCVR light responds to signals from Omega stationso P•Zanual synchronization is accn^mplished by depressing the HOLD button_ on the .front panel when the REF light goes off and releasing it when the desired station has illuminated the RCVR light. The alignment of the two lights can be refined by use of the ADV/RTD (advance/ xetard) control on the. receiver panel. Synchronization is complete when the REF and RCVR lights are illuminated simultaneously for a seleefis^d station.

A 5.102 Phase Tracking ^: .

Once the receiver is synchronized, phase tracking of the 10.2 kHz transmissions. from the Omega stations begins automatically. A single phase tracking loop time multiplexed .

between all the stations is used. By the use of this single loop, differential instrumentation errors between stations are eliminated and the tracking system error is reduced, Auxiliary features include an AFC loop to correct small errors in the system master oscillator and a S/N (signal-to- estimator is thres- noise) ratio estimator The S/N ratio S/N ratio of a station holded to drive a warning light if the t.

selected for navigation is insufficien 5.1.3 Position Calculation The position calculation circuitry is essentially a special-purpose computer which calculates various. parameters based upon position vectors in the Omega coordinate system whose origin is the position of the receiver when last reset (usually at the start of the flight). The present position of the .aircraft is computed from the outputs of the phase track loops and is stored as a vector from the origin to the aircraft position. The position of the desired waypoint is ~ supplied to the computer as a vector from the-origin to that waypoint. The. computer subtracts these two vectors to generate a vector from the position of the aircraft to the desired waypoint. The crosstrack component of this vector is displayed on the CDI, and the length of this vector is scaled. and displayed on the miles-to-go readout, By flying to keep the CDI centered, a great circle path. from the pre- sent position to the desired waypoint is achieved.

The Omega receiver was hard-mounted ir_ the test air- craft to facilitate. operation of the unit and to decrease the number of separate test items in the aircraft., It was fixed under the instrument panel on the right side of the aircraft, easily accessible to the co-pilot/Ortega operator. The indicator was installed in a spare opening in the instrument panel among the flight instruments; directly in front of the pilot below the artificial horizon, between the turn coordn- ator and the lower VOR indicator.

The antenna coupler was mounted behind the instrument panel near the ADF. The lead from the existing ADF sense antenna was connected to the coupler, .which supplied signals to both the A.DF and the Omega receiver but kept the two electrically isolatedo Proper grounding of the sense antenna was necessary for good performance of the Omega ___ ,_ _ ^ ..,....,... ^ _ _ .. . _ , _.^^,^,,.._..__ ^-_.r_ , _ receiver. Power for the Omega receiver was supplied by the aircraft 12 volt electrical .system via the cigar lighter.

Operation of the Mark III was straightforward in that two pairs of Omega stations were chosen and selected on the front pane`1 thumbwheels. The differences between the first waypoint (or destination) and the starting point in terms of changes in lanes (^ LOPs) .generated by the selected station pairs. were acquired from a computer program and entered using additional thumbwheels. The receiver was .synchronized, the CDI (Course Deviation Indicator) zeroed, ' and the miles-to-go counter set to the known distance from t?-^e starting point to try first waypoint. The receiver then displayed crosstrack deviation and miles-to-go during the flight, along with a to/from flag .indicating waypoint passage and a weak signal light which warned of excessively low signal-to-noise (S/DT) ratios.

5.2 .Custom Interface Unit (CIU) and Data Recorder The custom interface unit (CIU) was fabricated by Dynell Electronics to assist data recording and reduction.

The unit was portable to facilitate its use in two separate functions: in the air, for converting (digital) parameters from the rece^.iver to frequency-shift-keyec' (FSK) signals for ^ } ^t _ 1 recording on a standard cassette tape recorder; and on the ground, for demodulating the FSK signal to standard teletype format. (RS232C) for post flight computer processing of the data. A functional diagram of the airborne grid post flight data processing equipment used in the flight program is shown in Figure 5-3. The CIU received power from the Omega receiver, and it supplied power to the data recorder.

The CIU is housed in an aluminum box approximately 14" x 10". On the front of. the box are switches. for .3.25" x power on/off, circuit enable/disable, and operator discrete code select. In addition, there. are. three fuses on the front panel to ensure the necessary isolation in the event of power surge.. On the back panel are two input plugs, wired in parallel, and four BNC plugs: to tape recorder, from tape recorder, vDC power output, and teletype output o Internal- circuitry consists of CI^OS integrated circuits on a ly, the wire wrap board, with power supply components mounted separately.

The Mark III Omega receiver was modified to supply the following parameters to the CIU after each 10-second Omega cycle: 5,2 { ^ 1 1 ^t _ _ to ADgil Airherne Equipment C-Band Indicator Antenna Omega Transponder Unit Mark III Coupler Receiver ^^' Sense Transponder Antenna Antenna Operator Codes Discrete Portable Equipment Data ^ Voice Custom Analog Formulating Interfacd Tape Recorder ^ ► Unit I Demodulator Recorder {CIU) Playback Wang 2200B Minicomputer Ground Equipment Wang 2207A Interface Controller CRT Display Wang 2200 Digital.

Central Tape Processing Recorder Unit Operator Keyboard :Plotter. Printer Figure 5-3 Airborne and Post Flight Data Processing Equipment Functional Diagram ^_ .

! ^ i ..

a. LOP 1: present position relative to origin b. LOP 2: present position relative to origin c. Crosstrack deviation d. Miles-to-go readout e. Signal-to-noise ratio of each station (8) f. Weak signal indicator g. Auto-zero activation h. Reset indication i. To-from fls.g indication j. Operator disc^ pte code selection These parameters are all present ^^side the Mark III in digital form, and no A/D conversion is required. (The analog CDI is driven by a D/A convertero) The various parameters, timing signals, and DC power are fed to the CIU by a cable connected to the Mark III. The timing signals select which parameter or part of a parameter is .put onto an internal data bus which feeds the FSK converter. The. CIU output is routed to the microphone input of a standard portable cassette recorders _ ,.

Unlike the Omega receiver itself, the CIU was not hard mounted in the aircraft. Instead, it usually was placed on ^^ 1 1 ^ ^^ ^^ ;^^ ^.

iti 3e; is i' the back seat or on the floor of the aircraft. When data was to be recorded, the unit was turned on and the enable/ r disable. switch was placed in the disable position, This Caused a high frequency tone to be written on the cassette tape as a header, After approximately 30 seconds, the switch was placed in the enable position, allowing data to be written on the tape.

One difficulty encountered with the ^IU was the failure of the chip supplying the four most significant bits of the fractional part of the LOP 1 lane accumulator. This failure was detected after the first set of flights in the Wallops area. Since the chip was unavailable locally, it was replaced by the chip supplying the least significant four bits of the fractional part of LOP 1, leaving an empty socket.

on the board. This caused the least significant LOP 1 byte to be duplicated in the data string as the preceding signal- to-noise ratio byte, This known error was not judged significant as the maximum error this could induce was less than 0.0.625 lanes, much smaller than the observed noise in the LOP counters..

}: ^;

I ^ ^ ^ ^^

5a3 External Filter, Course Deviation Indicator and Strip ^h'art Reco'r'd'er A portable l2 vDC Rustak strip chart recorder was used on some n the early flights to record the CDI information as displayed to the pyalot.

An additional CDI movement was prepared to be mounted on the dashboard hand hold in the event. the Mark III.

indicator_ could not be hard mounteda This CDI used the Omega autopil^^X output to drive a standard movemento An external analog filter was designed (Refsa 28 and 30) and. built in order to provide external adjustment of the CDI sensitivity and to damp out some of the fluctuations.

noted when the first test flight was made. The input to the filter is the same Omega autopilot output used to drive either the auxiliary CDI or recorder peno The outputs of the filter. are independent circuits drivin; both the auxilliary CDI and recorder.

The filter was employed on only one test flight during which the Omega receiver drifted, S6 _..e

I !

I

5.4 .Voice Recorder ., A portable battery powered cassetted recorder was used for recording inflight noteso Use of a voice recorder obviated the need for knee--pad notes and allowed a much higher volume of data to be noted. The recorder has setTe:ral attributes making it extremely useful for this purpose: small size, no external power requirements, and easy control..

The small size of the recorder allowed it to be placed under the co-pilot/Omega operator's seato Because no external power was required, there were no superfluous wires to be attached and checked before flighto With the primary recorder controls preset, the recorder was started and stop- ped using a remote switch on the microphone, The tape recorder was activated only when recording was desired so voice records were sequential on the tape with no intervening dead time. This provided tape economy and freed the operator from .inflight tape c^ianging requirements on this recorder.

5.5 Piper Cherokee 180 Aircraft The flight evaluation program was conducted in a leased Piper Cherokee 180 aircraft (N4721L) based at Hanscom Field, Bedford, Massachusetts.. .The Cherokee is a four-place ..

general aviation aircraft powered by a 180 HP Lycoming engine. The electrical system includes a 60-amp alternator and a 12-volt, 25-amp battery, The aircraft ^:^as a standard instrument panel anal avionics including dual VHF trans- ceivers, automatic direction finder, glideslope receiver, transponder, single-axis autopilot and the Omega Mark 1.II Navigation System used in the flight evaluation s The air- craftspecifications and performance details are presented.

in Table 5-2.

y a^ ^ ^ ^ -; W^^ __ Dimensions, External.: Wing span 30 ft 0 in Wing chord (constant) 5 ft 3 in Length overall 23 ft 6 in Height overall 7 ft 3-1J2 in Areas: Wings, gross 160 sq ft Trailing edge flaps (total) 14, 50 sq ft Fin sq ft Tailp^.ane 24 ° 40 sq ft Weights and Loadings: Weight empty (standard) 1,330 lbs Max gross weight 2,400 lbs Performance: Max level speed at S/L: 132 kts Max. cruising speed (75%power) at 7,000 ft (2,130 m) 12,4 kts Stalling. speed, flaps down 50 kts Rate of climb at S/L 750 ft/min Service ceiling 13,000 ft T-0 run 720 ft Landing run 600 ft Range (75% power at 7.,000 ft) 629 nm

J

_; . Piper Cherokee Dimensions and Performance Table 5-2 ^.

Characteristics y f ^._ ^^ _ 1_ t ^, I 1, ;^ Section 6 GROUND EQUIPMENT. AND FACILITIES Flight planning and data processing necessitated Y considerable computation capability and extensive use ws.s made of the MIT IBM 370-65 computer and.. the ASI Wang 22008 and its related hardware. Arrangements were made to take advantage of the FPS-16 tracking radar at Wallops and the DABS radar at Lincoln Laboratory to obtain precise position information. Fixed position bench test sites were construct- ed at MIT and ASI to provide aground base for comparison.

6e1 MIT IBM 370-65 Computer The MIT computer was used in flight planning by calculating the necessary navigation input parameters used during mulitple waypoint flight tests. The parameters included LOP changes and distance between waypoints, magnet- ic heading and course n^,^.mbe:^: (vehicle course in hyper- bolic reference system) to the zLe^t xMTaypoint o Additionally the computer was. used to prepare tables of course number vs magnetic heading for use in enroute variation of flight plan .

such as encountered when receiving radar vectors or making full approaches with procedure turns.. Preliminary statistics ^. .a _._ .

were computed and printed on calcomp using data from the strip charts.

6.2 ASI Wang 2200B Computer System - The ASI computer system was employed during the joint MIT/ASI portion of the flight test program to reduce some 60 hours of cassette recorded data for post flight data analysis. A block diagram of the post flight data processing is shown in Figure 5-3. The elements of the Wang 2200B system are listed in Table 6-1.

Central Processor 2200B -1 2216/2217 Combined Display/Cassette Drive 2222 Keyboard Output '+triter 2201.

CPU Stand Analog Flatbed . Plotter I/O Interface Controller 2207A Step Memory Option.

Option 1 - Matrix ROM

0^' -1

Character Edit ROM Option 3 - OI'-3 ASI Wang 22OOB Computer System Table 6- .

The flatbed plotter was used to prepare the figures in Appendices A and B, Wallops FPS-16 Tracking 12adar and Lincoln Laboratory 6.^ DABS Radar Fo° ^° of the first set of flights {Flights 1-1, 1-3, 1-8, and 1-9), were tracked by the Wallops FPS- 16 tracking radar. For this purpose, a C-band transponder was installed in the test aircraft, The transponder was supplied by NASA and consisted of a battery pack, an antenna, and the trans- ponder itself. The battery pack was carried in the luggage compartment of the test aircraft and. supplied power to the transponder carried in the back seat. The transponder antenna was hard-mounted on the underside of the aft fuse- lage of the test aircraft ° Due to short battery life, the transponder was normally used only ,for radar identification of the test aircraft. After the aircraft was identified, tracking was maintained by skin track mode. During the .night flight 1-9, the transponder was left on to ensure against track loss.

Flight plans were prepared to employ the highly accurate position determination of the DABS radar by flying both enroute segments and RNAV approaches to Hanscom Airport.

_:__ _ ._, ^. _ ^ ^ Scheduling irregularities precluded the use of the .Lincoln Lab. faciltities.

6.4 Fixed Position Bench `Pest Sites Bench sites were prepared at MIT and ASI to provide.

received signals a low cost preliminary view of the actual and receiver indications as well as to provide background data to corroborate airborne indicationso The bench sites consisted of a roof mounted 8 foot whip antenna and co- located anteniza coupler with coupler lead long enough to extend to a convenient indoor location, and a well filtered 12 v DC power supply.

^ 11i ^$ {i it ,^ ^!

CI Section.?

FLIGHT TEST PROGRAM PROCEDURES This section describes the planning and proceduzesused in the Omega flight evaluation program. The importance of safety in flight operations was stressed throughout the program, and all operations were conducted in accordance.

with the ASI Flight Safety and Procedures Handbook. The following subsections include brief discussions of flight planning and check lists., data recording procedures and navigational techniques employed4 7.1 Omega LOP Versus LAT/LON Algorithms A series of computer programs were written in Fortran to convert position information from latitude and longitude coordinates to Omega^LOP coordinates by use of gradient vectors (H-vectors) linearized to a local . area (Ref. 3).

For example, a transformation from the relative change. in lat/lon to the corresponding change in A-B and $-D LOP between two points would be: Hl H2 ^1at DAB H3 H4 -41on x cos (lat) BBD t ^ 1 't +?

y, ;^ where H4 would be the change in the B-D LOP for a given change in miles east (see Appendix C• 2 )• This algorithm ^- s was refined in programming to produce the necessary waypoint a'.

{ ^ input parameters used with the rsark III receiver, A sample output for the Wallops area is shown in Figure 7-1. These ;; programs were also converted to BASIC for use with the Wang `" 22OOB computer. It was found that to remain witrla_n accept- able accuracy limits (.the. LOP changes are entered into the DR-30 receiver in tenths of lane increments) the linearize- tion was limited to a fifty mile. radius of the H-vector calculation point.

7.2 Preparation 'of Omega Aeronautical Charts ` A series of Aeronautical Sectional and Terminal Control Area charts were overlaid with Omega LOPS as the only other Omega charts available were not intended for or usable by ^: This was done for both the Wallops general aviation pilots, i area and the New England. Region, and provided a very useful '^ cross check to ensure waypoints had been computed correctly Occasional '' and LOPs properly entered in the receivers.

^` waypoint blunders were found and corrected enroute through These charts were also used for reference to these charts, t preliminary flight planning for determining optimal routing - ^^ 65 ^7 ^,i ^ ^ 1 ^ I f _ _.

tl TSPY Af?Ch ACRF TAER AWAI ADLM AMRG ASBY ^TO 38.33 38.34 38.47 38.47 38.33 313.32 38.02 LAT 37.94 __ 75.12 75.83 75.22 75. b0 T5.47^ 75.57 75.18 75.52 ^^^ION FRCM _ -Z.b -2.7 -3.5 -3.5 -2.b -2.5 -A.5 ANAL DAB A .0 C.7 1.8 1.?. 2.7 DBD 0.0 3.3 1.8 2.3 __ 28.3 17.8 2.6.3 24.8 DR ^ C.C! 32.1 34.6 23.3 494. 55b. 462. 5Gt1.

CN t7. 496. 4b7. 443.

_.._.

. _ 1.

7. 38. 117. 51. 30I. 4 1.

. - - t7.

HM 1.0 3.0 0.9 D.9 DAB 3.5 0.0 -C^.O 0.9 ADIM - 2. b -1.4 -2. 1 -U. b DBD -3 .3 (3.0 -1.5 -^? .'9 23.1 29.8 18.3 7.9 Q.0 18.2 8.5 DR 32.1 145. 64. 140. 81.

9b. (3. 2+^2. 102.

CN 13^. ' 205. - 178. 128. 22^^.

^-' ^ NM 187. 0. 105.

3.i3 G.9 t?.9 0. 0,.9 1.0 AWRG DAB 3.5 ! C 0.0 t7.9 0.0 O.b -1.1 n.l -4.6 DBD -1.8 1.5 40.9 8.4 z1.0 0.0 17..7 S.5 DR 34.b 18.2 795. 79. b98.

t1. 724. 1.04.

CN 67. 602.

244. 2Q8. 263: 285.. 0. 258. 176.

--^ HM 218.

-C .0 -O.n -r^.9 -1).9 0.0 C.1 2.1 ASBY DAB 2.6 -1.6 -^7.5 -1 .2 0.3 080 -2.3 t;?.9 -0.6 L1.0 _ 0.0 18.9 24.1 13.9 3.8 DR 23.8 8.5 17.7 37. 200. 581:.

94. 502. 324. 0. 191.

CN _ ..

233. 105 ._ . 2^9^l.'

19th. 358. 78. C. 1C8.

HM AWAL = Wallops airport Legend: A>:?LI^1 =Delmar LOP lane change DAB = AB AWRG =Warrington LOP lane change DBD = BD ASBY = Salisbury DR =point to point.

AOCrT = Ocean . City distance ACPF =Crisfield course CN = hyperbolic = To^:m of Berlin TBER refereY'ice = To'wn of Salisbury TSBY =magnetic heading HM Figure 7-1 Computer Generated Waypoint Input Parameters for the nark III Recei.^er in the Wallops Area ^. ^ 1 1 i when flying along LQPs in various directions. Finally, it was determined to be possible to derive the proper LOP changes to within .15 lane by observation of the charts alone precomputed programs or accurate mea- without reference to sures, making it possible for VFR enroute route changes with only slightly degraded accuracy.

Flight Planning 7.3 Extensive flight planning was conducted throughout. the program to take maximum advantage of each flight hour, This planning ranged from the broader aspects that included standardization of documentation, formats, procedures .and check lists for the flight program to the detailed aspects that involved determination of specific flight paths, air- speeds, altitudes, etc, for each flight.

Test Descr^tion 7.3.1 For each flight, a standardized information packet was made for each flight crew member. This. packet included a Flight Evaluation Sheet,. shown in Figure 7-2, a Flight Plan, .Figure 7-3, and a flight map, Figure 7 -4a ., _ _ _

_.__: ^

l 1 ^ Flight No.: 1- 1 Test Description Low altitude star route Test Objective; Provide initial. area survey of Wallops and mid Delmarva Peninsula at 5000" and selected lower altitudes with radar tracking ITEM PLANNED ACTUAL Date: 2/19/75 2/2G/75 Departure: 9 a,m, 10 a.^.

2,6 hrs Duration (hrs): 1 hr Low altitude Area/route: same star W. C. Hoffman same Pilot: Omega operator: P, V, Hwoschinsky same Other same participants: None VFP. same Weather: Winds at cruise: Calm 5 kts, N Data recording procedures: CIU on tape, voice log tape Contingency plans: no go if IFR Special requirements: Radar availability not required but useful ° Fly lower altitudes until radar track lock is lost-, Figure 7-2 Sample Flight Evaluation Sheet a '131 1 a .

DATE: FLIGHT NO.: 1 2/20/75 AM -1 CHECK° oLOP STATION TIME HDG C7 POINT ^, '^ PT^PT ETA p^ Op A-B A-D CN ^^Q ALT 8-D B -C ATA MH s.

Wallops 026 1.1 .9 15 8 8 arksley 231° -.1 115 5000 .1 2 300 .5 -.3 15 8 16 allops . G.

077° 115 5000 -.9 -.8 .2 3 519 - .8 15 8 24 ocomoke 328° 115 5000 1.0 .9 4 1.4 .6 11 21 35 etomkin Bland 185° 115 5000 -.8 -.5 5 517 .1 1.0 15 8 axis 331° 115 5000 .9 1.0 6 -1.0 278 -.6 25 13 56 082° Refuge 115 5000 -,4 -,6 7 -.8 -.2 10 5 1;01 Snow Hi11 115 5000 .6 p^ 287° .5 4 1.:05 8 0 7 08.7 0 115 5000 0 193° Wallops Figure 7-3 Omega Flight Plan Figure 7-4 Sample Flight Map JRIGINAI: PAGE IS OF POOR QUALI'TY^ r-..

^..

The flight evaluation sheet, shown in Figure 7-2, was designed to provide identification of and general information about the flighto The flight number and objectives were supplied at the top of the sheet, with operational data in the box at the center of the pages Operational data includes such parameters as time and date, a general description of flight rou}^e and duration,. participants, and summary weather information. Or_ the bottom of the sheet were data recording requirements, contingency plans, and special requirements..

go decision These three provided information to make a gojno based on flight test objectives.

ili s The flight plan is shown Figure 7-3. 'hi sheet was in a format standard for pilot usage and completely specified the test flight profile. Distances, headings, times and Omega receiver settings were all included. In addition, Omega receiver settings for additional LQP selec- tions were included so that station outage would not require termination of data collectiono was included A map of the proposed flight (Figure 7 -4) t` in the flight test packet with the desired path marked..

This provided a quick-look at the desired profile and wa.s ^.

n' ^ helpful in aircraft. ox^.entation on the charts actually used ^; r 71 y - i ...._ ._ ^^ k{^ ii G{ t": i }' il.

!i for navigation, In addition, it provided a convenient chart ;!

for clipboard use bt^^ observers .

',, 7.3,2 Checklists A comprehensive set of operational. check lists was made to reduce errors in the flight test program and. during ground transfer of data. Table 7-1 shows a list of checklist titles and Figures 7-5 and 7-6 are given as examples {Ref.. 1), Flight Equipment Checklist Flight Recording CIU Checklist Omega Warn Up Checklist Receiver Synchronization Chec^;.lists Ground Operations Checklist Inf light Operations Checklists Initial Voice Recorder Checklist Waypoint Voice Recorder Checklist Enr.oute Voice Recorder Checklist Table 7-1 Checklist Titles f -; _ ... _.

^_ _ _ .

, : , AUTO SYNC SYNC sw-ID 1, SYNC-select D (or other) 2 P.

Depress HOLD .momentarily .. 3 .

SYNC when. REF light on and off 40 (within 30 seconds) . SYNC sw-ON 5 6. Check Sync MANUAL SYNC to SYNC sw-ON 2. SYNC select-D (or other) 3. Depress HOLD when REF light goes off 4. Release HOLD when Proper RCV light goes off 5. Adj of ADV/RTD sw 6. Insert LOP letters Insert LOP numbers for Waypoint 7.

s. Reset lane accumulators Display 1^TTC, flag an FROM 9.

10. Adj MILES SET for distance Receiver Syrchrcni ?ati on Checklists Figure 7-^ ii 1. Time 2. Actual position Altitude (MSLj 3.

4. CIU discrete code 5. Waypoint in use 6. Course number 7. CDI 8o MTG 9. Weather Figure 7-6 Enroute Voice Recorder C^iecklist 7.3.3 Scheduling Over the period of study and performance of the flight experimental work was composed of four phases.

tests, the First, fixed position ground tests were conducted to deter- mine the stability of the indicator outputso These locations included the MIT bench test site, the top floor of a sixteen story building and in an automobile both parked and moving.

The second phase included experimental design teamwork more on a method of filtering the CDI presentation to a acceptable indication of crosstrack error without losing ^_ S information. necessary for accurate course following. Consid- erable effarr and consultation was made in the design, .

r redesign, and ^or;struction of a Tight weight, compact, low .

power filter.

The third phase spanned the period of initial flight tests and hardware mounting decisions to the shakedown flights with the CIU on board and receiver and. indicator hard mounted. This period also included a majority of the actual flight planning and data standardization.

The fourth and final phase encompassed the bulk of the data flight tests, data reduction, analysis and evaluation of results. A last series of flights was made after the bulk of the data analysis to confirm partially resolved conclusions .^ . ^^ ^^ 7.4 Data'Recording Data. were recorded in the aircraft on two airborne tape recorders and on maps., .Ground data consisted. of FPS-16 radar tracking at Wallops Island when available., Tape recorded data included the digital output of the :CIU and voice records. Map records and radar data were used for r position plottingp ;7 t _ _ ^ ..... .,..1 _ 7.4.1 Omega Data As described in Section 5.4 and 7 0 3.2, various Omega receiver parameters were recorded on a portable cassette recorder. During data reduction, it was discovered that the Omega/CIU/recorder system also recorded transmissions from the aircraft VHF transceivers.. Most Omega data flights were made with radios off, however, and very few transmissions were made on flights with. the radios on. Thus, little data was lost.

The tapes used for the recording were standard audio quality tapeso Because of memory limitations in the processor, the. standard tape length was 30 minutes per side.

However, some recordings were made on 45 minute tapes, which were processed in two parts. Performance of standard tapes was adequate, and there was no requirement for any high fidelity tapes, or high fidelity recorders incorporating high frequency noise reduction circuitry.

Time synchronization on the Omega data tapes was achieved by setting a new operator discrete Cade on the CIU With this reference, the times of both at a known time.

previous and subsequent data strings could be determined, _ x _ ^ _ l ^ _ 3 t y .

unless severely garbled data intervened. Few such problems were encountered.

h Tape Log 7.4.2 During the flight . evaluation program, pertinent information was verbally recorded on a cassette recorder.

This provided the capability to process data later with extensive and complete notes of the events of the flight..

The voice recorder was usually operated by the gmega receiver operator.

Figure 7-7 shows a pocket. size check list used for recorder operations The first section was used to insure that the recorder itself was operating, the second section of the check. list was used to insure that entries on the tape were complete and appropriate. Transcription of voice tapes was accomplished as soon after each flight as possbc to ensure optimum accuracy and detail. A sample transcript is shown in Figure 7-8.

!

_ 1 r_ I Check before Flight: All. wires properly connected ^` Voice recorder working Voice recorder battery level in green CIU recorder working Voice Log Entry Update CIU on C, check enabled: Time: (hour) min, sec (Waypoint change) r (T/F) MTG CDI Event.

(CN) (Wsl ID) Location and Ac ion Figure 7-7 Pocket Size Checklist . for Voice Recorder 7..4.3 Position Plotting iL the Aircraft position was plotted manually on maps In addition, position plots were cockpit when possible.

^: available from the tracking radar during the first series of ^; L.

r t ^ ^ Omega Flight 1-1 Notes (20 February 1975) Low Altitude Star Route Location and .Action Time Wit T/F 2T1G CDI Event CN Wsl 1/2 It of course to Parksley 10:33:30 T/F 1 2 It 2 A Over Parksley, radar mark, 10:.34:12 2 T 15 C toward Wpt 2 10:3 7 ^.

A Over coastline 10::38:12 3 2 1 1V'1nT Wpt 2 10:40:52 4 4 rt A 3 NE Wpt 2 ^ 10:42c12 T/F 0 C 5 T C G 515 A Autozero over Wallops Coast 10:44:02 3 15 Guard Over inner coast toward 10:4$:12. 7 7 4 It Pocomoke, I mile rt of course Abeam S^TL VOP^ 1.0:50:22 2 C 3 Crossing powerline from SBY 10:51:02 to WAL, 2 SW Pocomoke City Figure 7-8 Sample Voice Transcript ^. ._ ^ s s^'•^ s F1251 h ti ls^; ^ `_ ^^ ..

ear ^rinN^ e zz u^ R°^ 1 AL_ ^^'^^ Old Lyme r.

. .z ^ ^ VQR ^ ti^ (^ 10t /UMS^ UL t_ i0^ .v tF^G 1t _ _ ^^ :" e - WINtISOR l 5 N Saa^dy PF ^ 1 `S^P^SO \ Y/ROUK — CZ eH Oi ^ ^ R^ IEADOW ^^ daily and a ^ ^^ ^$ DyNOi^ JAL WILDLIFE REFUGEp^^^ ^ BLOCK tSIAND ^TA'>"^.

w^rcM rut r0!(tl?SU-1 ^"^{ . y H R USH Iq^ Pf , ?0 ^^ ^t- r n n g e i r-- R8n - 6o^ % r FF -- t ^^ ^ MONiAUN P1iNT F35'ill ^^_• ^ r y em .^^' L 11i1D'^ k y PORTE K I 2a - 35 U 1 ^ K ^K \` rAoMa^vr NSW ^ 3 ^ =ardirttvs `*-, Rek.w N ► .i .^!

Figure 7-9 Typical Manual Position Plot ORIGINAL PAGB I3 Off' POOR QUALITY( i i t ' # '. ,1 ^ Wallops area flights, and position plots were made from Cl'U recorded data for the second set of Wallops flightsa On the early Northeast Corridor flights, position plots were drawn by hand in order to estimate necessary corridor widths for VTOL service. An example of such a plot is shown in Figure 7-9. In the Wallops area flights, position plots were occasionally drawn as a crosscheck. Finally, position plots were made following a fa;.lure of the voice recorder.

This salvaged flight data which otherwise could not. have been correlated with encountered phenomena, Navigation Techniques 7.5 A variety of different navigation techniques were employed during the flight program so that comparisons could be made with a wide range of other test data and to assure reliability of measuxed accuracy. In both the Wallops area and the Northeast Corridor, all the tested forms of navigation were used in different flights over the same regions to provide corroborative data. The most common technique was navigation using Omega with visual position checks for confirmation, Occasionally this was reversed by flying visually and recording Omega position information.

gl ^ Additionally, VOR radials and ILS localzers were used for navigation with the Omega position recorded for comparison.

Finally, Omega routes were flown under radar tracking, with the radar position information supplied later for comparison.

7.5,1 Omega Navi ation On many flights, including most of the Northeast Corridor flights, the aircraft was flown using the Omega receiver as the primary navigation deviceo This provided data on how well the pilot was able to fa:Llow the Omega generated needle deflections, and also gave data on pilot reactions to the position information and required techniques.. Position reports were entered on the voice tape for statistical analysis of the errors, One major advantage of this mode of navigation was that it allowed the major noise source in the flight evaluation program, the air- craft VHF radios, to be turned off.. Several nonprecision approaches were flown with the Omega along with final way- points usually within the airport boundaries, but at least within. one nautical mile when corrections were made within a hundred mile radius.

_: __ _ __ - E ^; I+ ^ 1.

_a S s 705.2 VHF Navigation Many flights were conducted using VOR as the primary navigation source, with the Omega recorded position used for comparison with. a known ground track„ In the. Northeast Corridor, VOR was used for enroute navigation; and in the Wallops area, VOR was used to provide navigation for flying precise patterns in the Snow Hill area. Omega was used to navigate the aircraft to an ILS approach path at Salisbury Md., and the Omega was monitored during the approach, On most ox the Northeast Corridor flights, L-he Omega receiver was used as the primary navigation source. However, IFR operations and some Boston area local flights used VOR for primary navigation, and the position recorded by the Omega set was analyzed for comparison.

At Trlallops, the Snow Hill VOR was used far primary navigation an many fl.i^hts. The VOR was used to define radials along which. the aircraft was flocY-n. By comparing the Omega indicated position to the known path, anomalies such as the coastline effect were in^resti.gateu, and navigation information. was provided tt^.rough areas where Omega interference was suspecteda F3 3 ILS paths Taere followed on flights 2-11 and 1- 24 (discussed later). Un these flights, the Omega set was adjusted to correspond to the ILS readout, but the ILS was } used for primary navigation, Again, the Omega rasition was later compared with the assumed aircraft path.

7.5.3 Visual Navigation The visual navigation mode consisted of contact flying with voice r;.ports at regular in ervals recording actual position relative to knot^m landmarks. This information was then reduced with CIU supplied information for verification and comparison with the Omega indication of position.

Examples of flight segments where visual navigation was the preferred mode included: flying through the I1ew York TCA along the Hudson River, flying along a straight section of a railroad on the Delmarva Peninsula, and crossing expanses of water at low altitudes The main advantage of contact.

flying was the ability to navigate without the VOR receivers on, which was the major source of .interference for the Omega receiver.

Section 8 POST FLIGHT DATA PROCESSIDIG A very large volume of data was recorded during the flight evaluation program. Thus it was essential that an efficient computerized data processing and plotting system '- be developed to provide rapid reduction of the data for sub- sequent analysisa This section includes a brief description of the post-flight data reduction system including the data processing equipment, the data reduction software, and plot- ting capability, A majority of the software generation and data reduction was accomplished by an ASI/rill team (Refs, 1 and 28) 8.1 ^.^ta Processing Equipment A functional block diagram of the post flight data processing system is shown in Figure 5-3. As shown in the fig^lre, the data. processing equipment consisted of a Wang minicomputer with peripherals including an output 2200B typewriter, an analog plotter, a cassette tape and a tele- type interface t^oardo The elements of the ASI Wang 2200B minicomputer installation are indicated in Tab le . 6,1. '.Che F is programmed entirely in BASIC.

2200B v I I '^ I 802 Data Transcrip tion and Checkin In the air, data was recordedrn 'the portable cassette recorder by the custom interface unit as described in Section 7.4.I. On the ground, the cassette r^;corder was played back through the CIU to generate RS232C teletype data for input to the Wang processor through a teletype interface board.

Tt was discovered that some transmissions from the aircraft VHF transceivers were recorded on the cassette recorder along with. the data, resulting in garbling of datao 8,3 Plotting Capabilit The recorded data were processed to yield several different types of plots, These plots included S/id ratios, Omega estimates of aircraft position, miles to go (MTG), various status flags, and needle def7.zction. These are discussed in the following section. a Miles-to-Ga Plotting 8.3.1 The miles-to-go (MTG) was plotted on a linear scale of 0 to 75 miles, with tic marks on the y axis representing 25 mile steps. No filtering or special processing of any kind was doneo A blank space was left on the plot, indicating

' I I 1 ! ^^

deleted data. In addition, space was left to indicate the lack of data acquisition while a cassette was being changed in the. aircraft .

8x3.2 Status F lag Flots Four status flags were recorded by the CIU: to/from flag, autozero, lane accumulator reset, and weak signal on any station used for navigation. With the exception of the to/frornflag, which was plotted as a continuous bistable position line, each flag was plotted as a tic mark above the x axis when it occurred. Labels for these flags are shown on the plots presented in Appendices A and S.

803.3 Needle Deflection Plotting Needle deflection plots recorded the deviation of the needle deflection calculated from the phase meausrements at the end of a 10 second Omega transmission sequence, In practice., the needle was prone. to oscillations at frequencies higher than those recorded by the sampler. These oscillations.

were apparent to the pilot and required the .pilot to manually filter the CDI readout.. As in the miles-to-go plotting routine, breaks in the. data . result in discontinuous plots of needle deflection _ i

. ^^ l ^

^^l

^^

^^

S/N Ratio Plots 803 04 The needle deflection plotting routine also Blotted S/N ratios as a user selectable optionp S/N was recorded as an 8-bit S/Z1 count number between 0 and 255, which gave an estimate of the S/N ratio according to the formula Count number = 12$+100 x (broadcast time of Omega station)X ERF ( 3 S/N ^ po ) The plotting routine used code to limit the signal-to-noise ratios to a minimum of -30 dBo The maximum was based upon tr mission time. of .the station the ans ^, r y gg k^ li

-.l _ _ _ l ,, Section 9 FLIGHT TEST PROGRAM RESULTS As detailed in Section 2, the objectives of the Wallops area flight tests were to investigate the various effects due to altitude, coastline, station. pairs, LOP geometry, diurnal variations, precipitation, radio frequency interference, maneuvers, and geographic location. These effects were then to be analyzed to provide initial information and flight experience for the differential Amega flight test and evaluation program. The objec fives of the Nor'the^zsr. ioiridor and New England Region flight program were to repeat previously flown low altitude .Zulu routes to compare Omega perform^;nce with VOP. /DP^lE results. Factors investigated included; suitability and accuracy of Omega navigation for city center VIOL operation, performance at various altitudes over various terrain (urban, industrial, forests, mountains, water), effects of maneuvers (holding patterns, simulated approach, missed approach), and ground versus airborne performance.

Flight planning included plotting Omega LOPs on aero- nautical sectional and terminal control area charts, pre- paration. of LOP versus position tabulations and detailed $9 _ Y i _ _ ^ flight descriptions as discussed in Section 7.3 to ensure complete coverage of test objectives. Contingency plans were formulated for IFR T,aeather and for periods when. part- ,^ icular Omega stations were off the air.

Flight. status and summary tables were prepared to provide rapid. comparison of the various objectives completed with those yet to be examined, these are shown in Table 9-1 through 9-4. As ran be seen. in the tables, the sixteen Wallops area flight tests were made in two groups; the first from February 19 through 22, and the second March 7 through 9.

The first group of eleven included four flights with radar tracking. These were in two pairs, the first pair being a comparison of low and high altitude routes at five and ten thousand feet, respectivelya The second pair compared the same altitude and route before and after local sunse^,:. Three of the. remaining flights were refueling trips to and from Salisbk^xy conducted at varying altitudes past Snow Hill. VOR, The remaining four flights compared different types of navigation including: contact flying along the peninsula railroad; airport to airport flying using VORs, NDBs through the Wallops area; and VOR radial flying r^erpendcular to the coastline on Assateague Island.

,, s • r r r r r r- ► r r r r-' z^ r r-^ r r r r ^ v In ^ W N r O W N N N N N r ^D 00 a` .^ w N r ® o ^ ^, n rr N N N [^^ N W W W W W N N N N N R?

N N N N N N r ^D o0 00 ^I V N N N N Date (1975) tiD

N F-j !-^ 1-' r O O O O O

W

r

r N tv o 0 w N N r o t-' t-- + ► -^ o w r o o Flight hours

b

w ^ ^ o .^ ^ ^n w a^ ^ o ;-^ v w c, oo Coast ^ ^c ^c rc ^ ^c ^ ^ x ^ ^ n x ^ ^ ^ ^ ^ Altitude ^^.

w• ^: ^ ^c Station pairs oa rt LOP direction ^: ^ ^ ^ ^ ^ H m x ^ x Diurnal D,

0 ^ Precipitation

x

d

^.

m Interference r ^c p c ^ ^ p c ^ c ^; ^c ^c ?c ^c ^C p ^ x c+ ^ ^ ^ ^ ;,^ Maneuver s x ^c ^ ^ 5c ^ ^ ^4 ^ ^c ^ Accuracy Terrain ^ ^ ^ ^ Radar N O N o o w iv o t-^ F-' l-' t-d r o o N Mours data recorded e o o o • o • v o • • o w OD F-a rn N w v rn^ o Oo i1S w 6tt .^ -P ^.^.

i I „-

Flight

Number Flight Description 1-0 Ferry flight SBY-WAL (7500') 1-1 Low 4ltitude star route (5000', 4000', 3000', 2000') with radar 1-2 Ferry flight WAL-SBY (1000') 1-3 High altitude star route (10,000') with radar 1-4 Ferry flight WAL-ORF (1000') 1-S Night beacon and VOit flight ORF-SBY-WAL (3000' ) 1-6 Modified snake route WAL-MFV-SBY (2000') 1-7 Ferry flight SBY-WAL (1500') 1-8 Day -race track route with radar (3000') 1-9 Night race track route with radar (3000') 1-10 SWL VOR constant radial flight (n000', 5000', 4000', 3000', 2000') WAL-SBY 1-20 Ferry flight SBY-j^AL using AB, BD, LOQs at 2090' Railroad flight to Kellam 1-21 in heavy rain at 1000' AB/BD, AC/BD, WAL-SLY I1-22 Constant LOP octopus using AD, AC, AB, BD, BC LOPs SBY-SWL-SBY (2000') VOR cloverleaf 30° cardins.i headings {3000'), I1-23 SBY-SWL-SBY VOR cli^Terleaf 30 ° cardinal hr^adngs plus or I1 -24 minus 15° (3500'}, constant. CD LOP, AB/BC, CD/Bh, AB/BD Table. 9-2 Wallops Area Flight Summaries ' 1-_ b U c11 }^.^ q p ^ ^ }-d F ^ • i-1 •rl U t ^, cd a ^ .0 N ^ S-# ^ Flight ^ ^, ^ ° ;^ ^ ^ ^ ^ •^ ^ ^ .

.a a^ ^.o ^, •,^ Number .0 u N a^ ^ ^ ^, ^ ^, a- ► •^+ ^a ^ ro w ^ a^ ^ ► ^ u u ^ ^ r-+ ^s o ,-^ u o •a v ^+ ^ ro as ro c^ <C A t^ to ^+ ,^-^ f^ W ^ H ,z ^ ^ ^

(1974)

2-1 11/22 X ,3 X 0 2-2 11/23 X X 2,1 0 2-3 12./3 3,6 X X 1^5 2—Z1-1 12/20 2.2 X X X 1.5 (1975) 2—Z1-2 1/ 24 2 ti U X X X X 1 p ^, 2- 1/27 X

4 .9 X X X 107

h 2-5 1/30 X X 1.7 X 100 2-6 1/31 X X X X X 1.6 ^.^5 2-7 3/7 X X :^ X X X X 1, 9 I.0 'X 2-8 2/10 203 X X X 3 n5 2^-9 2/10 1.7 X X X X 1, 5 2-10 2/14 3,7 X X X 3,0 2-11 2/17 3,5 X X 3^4 X X^ X X 2-12 2./19 3,5 X 3.4.

X 2-13 2/22 3,1 • X X 3,0 X X X 2-21 2/27 1,3 X X 1n0 X 2-31 3/5 0,7 X 0.5 X 2-41 3/9 3,2 X X 3.;' X 2-44 3/9 3.5 X X X X 3. ^.

X 2-51 4/22 3,6 X X X ^ X 3.5 Table 9-3 Northeast Corridor Flight Test Object^.ves ^ ^ ' !, i` Flight ,Number Flight Description 2-1 Local. check flight BED-LWM-BED 2-2 Zulu ferry flight to FRG for mating CIU, BED-FRG 2-3 CIU pickup and 4721E dr_opoff, FRG-BED 2-Z1-1 4721E pickup and Zulu-1 flight FRG-BED 2-Z1-2 Cnnega pickup after repair FRG-BED 2-4 Local airport might flight,. LOP ^f2 sign chip bad 2-5 Drop off enroute to Princeton BED-FRG 2 -6 Pickup on return front Princeton, direct flight.

FRG-BED 2-7 Local. noise sensitivity check BED-TWR-FRM-GDM- IiST-BED 2 -8 Zulu attempt t^ Washington D. C., D lost enroute over Statue of Liberty BFD-FLU 2-9 Return from Flushing using A, B, C, BDR-BED 2-10 Zulu to Washington D. Ca, north route, BED- College Park IFR return from Washington D.C,, IAD-ARP-LHY-BED 2 -11 Zulu to Washington D, C^ with divert to SBY 2-12 enroute to WAL, BED-SBY 2-13 Zulu return from WAL, SBY-BED 2-21 Night repeat of 2-7 to test system with chip exchange 2-31 Ha^rerhill-BED ferry flight 2-32 Day ground test of CIU at BED Zulu-1, south divert to SBY via airports 2-41 2-44 Airports to Zulu-1, ,at high altitude (5500' and.

7500', SBY-BED Mountain flight near Mtn Washington (2500' and 2-51 7000') Table 9-4 Northeast Corridor Region Flight Summaries ► ^ __^ ^ ,.

._ .

_ -, f^ '.

i The second group of five flights was conducted without radar tracking and. included: airport to airport navigation using Omega alone; a repeat of the railroad flight using alternate LOP pairs and accompanied by heavy rain; Omega f ` r navigation along various LOPs from the Snow Hill VOR; and ' two VOR radial flights comparing . afternoon and morning signals in a flower petal patternp The twenty Northeast Corridor region flights were accomplished during the period from November 22, 1974 to Larch 9, 1975, with the majority of flights held during the .latter half of January and middle of Februaryo (Five of these flights had data. lost in transfer.) Four flights were conducted in the local ^3oston area far equipment operation verification and calibration. One flight was conducted.

during heavy rain with very poor S/N ratio for Station A> Five flights occurred entirely at night and two more before and after sunset.

Altitude Effects 90l All the Wallops area flights were concerned with the effects of altitude to some .degree, but as can be seen in Table 9-1, only six were specifically addresued to this phenomenons z 0'n the Northeast Corridor flights, S/N varations witb^ altitude, S/N variations at takeoff, an,^ ease of rLeedle - following at various altitudes were investigated. The majority of these flights were flown at a nominal ^00!D ft a MSL As Table 9- 5 shows, however, these flights ranged from 500 ft MSL to 7500 ft MSL, getting to within 20Q ft of the surface in order to detect S/N variations with aatitu.de, both in general and in specific areas. Altitude ef^eLts appeared to be limited to locally generated noise (a, g., the ITT low- -. frequency communication transmitter in Conunack, New York, on ` Long Island). Changes in station signal strength at takeoff were first noted. during the. early Zulu route tests. The ease of following the CDI Baas directly correlated w^.th Station A S/N ratio, but uncorrelated with altitude.

4.1..1 Expected Results .Proximity to local noise sources on the ground led to the expectation of higher signal to noise ratios at greater altitude. Also, modal interference was expected to be greatest at the edge of the waveguide (the ground or reflect- ing ionospheric. layer), avid again more stable signals were expected at higher altitudes. The. satin` reasoning also to the local terrain and coastline effects. Diurnal applied !

1 ., ^.

^, i^ ! 6`.

Fl i.^t

2-1 3000 ft MSL 2 -2 200() ft then under NY TCA at 1100 and 500 ft 2-3 2000 ft MSL rt M5L 2-21-^. 2000 ft MSL 2-z1-2 3500 'L-4 30+30 ft AGL 2-^ 2500 ft MSL 2-^i 5500 ft MSL ft AG'L with .200 ft portion over power- 2-7 2000 line 2-3 ?000 ft MSL then 1100 through NY TCA 2-9 3000 ft MSL YdY TCA 2000 ft except 1100 ft through -10

2 - lt 7000 ft (IFR)

except 1100 ft through NY TCA 2- 12 2000 tt except 500 ft through NY TCA. I 2-13 2000 ft 2-21 2000 ft AGZ 2--31 1500 ft MSL 2=41 2000 ft IMSL except 500 ft through ICY TCA ft MSL except 7500 ft over NY TCA 2- 44 5500 ^, pi anr^ 7000 ft MSL.

2- 51 q 2500 ft __..

Table 9-5 Northeast Corridor Flight ,A'ltitudes i' ^' ^: ^7 ^: ,,,, a ;,: ^., a effects were expected to be independent of altitude due to the macroscopic shifting of lanes caused by diurnal changes of the ionosphereo Preci^aitation effects were also expected to be independent of altitude because of the extremely local nature of precipitation static and its independence of a1':'itude. Finally, a number of previous tests had indicated an improvement in signal to noise ratio after takeoff, indicating: a strong ground effecto Takeoff Phenomenon 9.1.2 ^` ^, `^ The takeoff phenomenon is described as an improvement ^^ in S/N ration as the aircraft leaves the ground and climbs ^ - above the local treetops. A signal maskingeffect by trees i and local terrain was investigated by Mr, Caroll Lytle of the NASA Langley Research Center (Ref. 29) and is believed to be 3d the cause of this phenomenon. the effect Baas first noticed f ^. dur ng Northeast Corridor flight tests without the C'IU, By observing the weak signal light on the indicator and the _ receiver xefer^nce light, a fair knowledge of individual sF station S/N ratio was obtained, During some fli_glts where ,, Station A (Norway) appeared weak during ground runup of the "` ri aircraft, the number. of weak signal lights reduced. dramat- ^^ r; tally after takeoff.' This effect was observed an a few of ^_ .^ ., 9 8 a ^.,..:.

^ s ; i .+ ' the W^^.lops a:cea flights (e, g., Flight 1-9, Figure A.4 2), ^_: but was morF; obvious in the Northeast Corridor flights where ';; ^ t^^,e phenomeizon of S/N decreasing during landing could be ^r }^bs%rvpd, see Figure B.3-2 and B.5-8a This effect is not a t pa,rticular?.y strong one, and is easily masked by other ^`^ effects such as inverter noise change (discussed in Section ^; r: 9.4) .

A comparison of observatior_^ made wits the Ornega re- ceiver in the test aircraft and at the ground test site indi- cates that the. receiver is less affected by small disturbances in phase at the ground site, but more affected by the drift- ^^ ing of 6C Nz powerline noise.

9.1..3 Accuracy Accuracy was not so much a function of altitude as was the level of difficulty obtaining position information accurately as altitude increased. It has . been reported that there is no significant. change in signal strength noticed with altitude. However, less noise was sometimes present at higher altitudes (Refo 30), 9.2 Coastline Effects Eleven of the sixteen Wallops flight encountered some _._ i .. __ _ _ _ _ _ ._ coastal crossings and for those, seven were designed to deter- mine the magnitude and direction. of the effects on the LOPso 9.2,1 Expected Results It was expected from the nature of electromagnetic waves traveling over areas of different surface conductivity that the w^:;es would be retarded slightly when passing into a region of lower conductivity (Figure 9-1, Ref. 31). A rather simplified approach to the expected geometry of hyper- bolic LOPs near a coastline was obtained by plotting wave fronts (lines of constant propagation time from two stations to an observer on the coast and comparing the please differ- enceso Figure 9-2 shows typical coastal path geometry (Ref.

6^. These coast effects were expected to be greater at lower altitudes due to proximity of the coastline. Finally, due to the long transmission paths and relatively long wave lengths, several hundreds of_ miles of propagation anomalies are required to make even a small shift in the local phase ..measurement, such that extremely small local coast changes would have a miniscule effect (Ref. 6)0 T' L-90Ut:0 CO^WCTIk1TY 1G ce^unD cor,DUC71YlTr GPOUND COkDUCTIYITY Iry —sr millurhos per neat ' ;^ - S mJlimhps ; er mein mttu ^^ T nillimtro. Itr ( t e F SSr ^O w^S F'^l ^O r S NOgry,^s r p WFSj l Sp^N y p 9f psi F4t} z o ^ fSSl i W-^Tyt^pSpirH Ip ^^FSI Tp ^._ ASpT9 W ` •I WVTTp0 SpG7y fgSf z ca N N °_^.

E] 7^ 90 ED li TO 90 69 7D FD ea HEIGHT Of 10505PHEfiE (kilometcrs^ Figure 9-1 Attenuation of the 10.2 kHz Omega signal as a function of ionosphere height for different ground conductvitieso The. conductivities given are typically those for sea-water paths (infinite), good-conductivity land paths ity millmhos per meter), and poor-conductiv (5 land paths as found in the Arctic (l millimho per meter). (Ref. 31) S --^- H Figure 9-2 Typical path geometry showing master, slave and observer positions for propagation including both sea and land paths (Ref . 6) , 902,2 Observed Course Bending The actual path change commands observe. on the CDI when . passing over a coast in the Wallops area appear to have little correlation with subsequent passes over the same or similar spots either in direction or magnitude. The magnitude of the bends was on the order of o5 nm (Ref, 1); which is less than the phase noise in the. Norway signal,. and under- standable in view of the level of difficulty of holding a constant heading over an irregular coastal area in moderate air turbulence o Some course bending has been observed along the Connecticut coast near the hSadison VOR, but it was i.n proximity with a significant amount of HF and VHF energy.

loz r Flights over the Massachusetts and Maine coasts show no path bending at a11.

9.203 Variation with S/N Some of the path bending is due to random noise in the Station ,A signal, as mentioned above; and may be partially due to local HF marine radio broadcast energy leaking into the receiver via the ADF antenna (Refs. 12 and 30). Flight -22 1 was flown along a constant LOP and the plotted output should have indicated. a strai^;lit line, An airborne sketch was made of the visual track over the ground and needle deflection corrections were overlaid. The result was a fair- ly straight path.

9.Z.4 Variation with Xltitude As mentioned in Section 9.1,3, the inaccuracy of position measurements. increases with altitude, There was ' no increase in noticeable path bending at higher altitudes.

Close comparison of the VDR he^.ding information with Omega in the Snow Hill coastal area showed no more than internal _ receiver position uncertainty (Ref. 1).

_...:.: 1 1 9.3 Diurnal Effects The flights in the Wallops area were staggered through- out the day to determine the extend of errors accruable. due to the different diurnal shifts in the Omega LOPs (See V Figure 9-3). Selected flights in the Northeast Corridor region investigated diurnal effect errors (Table 9-3).

9.3.1. Expected Results There are three basic propagation paths: entirely sun- 1it (day), entirely dark (night) and mixed illumination (transition). As is mentioned in the Omega Prop^.gaton Correction Tables (Ref, 3^), wave propagation has a tendency toward greater stability during the day, but with slowly varying conditions. Night propagation conditions are less stable but more constant than during the day. The transition periods caused the most difficulty because the changes are intermediate stability and . occur nonlinearly.

of As the flight schedule shows, the transition periods.

fir Station A and C (Norway and Hawaii) are the longest, due to their great longitudinal d:isplacemen and present the greatest possiblity for diurnal errors ° Table 9-6 shows expected periods of inaccuracy due to diurnal effectsa .

T^^ ^^^ Number ^ ^ ^ ( ^ ^ ^ ^ ^ Station A ^_ ^;;, °—^ Station B ^' Station C + ^' 4;^ ' r ^4

+^

^ 1-1 ^i H 1-2 1-3 ~^

H

1-4

^----^

" 1-S

r----^ `^ i-6 r H 1-7 ^ 1-8

-i

^- 1-4 zi r I-^ V fi Station A ^' Station B °—^ f Station C ,^ jr" o--0 .Station D ^; 1-20 ^ r, H 1-21 F------I 1-22 Y;.

1-23 ^ '' ^-f ^' 1-24 ^-

l

I I I I I I

I I

I i I I I -tl

^; i I

. EST g 18 19 20 21 ^2 ^3 24

g 13 14 ZS 16 17 10 11 12 Wallops Area Flight Schedule and. Station ^; Figure 9 - 3 Transition Times r ;e "- i ^ Station Transition Occurrence at Wallops (EST) 1147 - 1742 (sunset.) 0056 - A - Norway 0651 (sun-

rse)

1742 0556 - 0651.

B - Trinidad 1647 - 1742 - 2311 0651 - C - Hawaii 1220 1912 0651- A - North Dakota 1742 - 0822 Table 9-6 Station Transition Periods for the Wallops Area (February 21, 1975) The operata..on of the Mark IZI receiver as explained in Section 5.1.3 removed some of the effect of the diurnal changes by employing only the relative changes. in LOP way- points. This essentially provided the navigation ^•^ith a differential Omega fix at beginning of each flight or after the last reset time.

Errors Accrued Du^ •ing Transition Periods 903 .2 Tcao Wallops area flights occurred during the sunrise shift, eight during the. early sunset shift, two during the late s^inset shift and five occur during mixed transition and daylight conditions. Figures 9-4 and 9-5 show propagation corrections. and rates of change of corrections respectively for the Wallops area.,-:and from this it can be seen that LOP changes occur in a non-uniform manner for .each station, On ^ ^ ^ i II 4.'

^.

``` Centicycles Sunrise Sunset ^^ r ° ° 8 ^ ^ ° ° a c c c k K k ^ ^ w K k —l.^ Y ^ ^ Y ' p ^ L k o -20 a ' ° .. e k a o k —80 * x ^ r4 x x x x ° x k x ^ -40 ° ,.. O ° ° ° ^ ^ ° ° u Y n o v (^^ —SO ^ ^ ^ ^ o -60 ° _ ^ ° ' ^ —7^ ° -80 ^ a e ° -90 ° ° ° o —lQQ 23 1 15 17 18 1 20 21 3 4 5 6 7 8 9 10 11 ^ 13 14 16 19 T1 Wallops Area Omega Propagation Corrections for Figure 9 -4 A, B, C, and D for the 10,2 kHz, Stations Period February 15-29, 1975 (40,ON, 74.OW) t, ^enCicycles Sunrise Sunset per hou +30 ^ J c.

' +20 v ° w a !E a +10 x Q o ^ b o -10 ^ ° ° w -20 • ° c -30 __ 1 2 3 4 5 6 7 8 9 10 11 N 13 14 15 16- 17 18 19 ly 20 21 22 23 M 9-5 G^^^11ops Area Omega PPC Changes for 10..2 kHz, Figure Stations A, B, C, and D for the Period February 15-29, 1975 (40.ON, 76.OW) Legend:Station A o Station B n, Station C o Station D -^ t ^: J.

^ tf i1 ii r ,' }F t I '^ Flights 1-22 and 1-24, Omega navigation employed Station C during its sunrise period, with no great loss of accuracy ;.

even though this was the period and station with the greatest ^' change. During the first two hours of Flight 1 -24, which employed LOP pairs AB and BC concurrent with the sunrise transition for Station C the Omega waypoints were compared with the VOR waypoints. Although there was a 1-1/2 nm accuracy degradation, it was less than half the magnitude expected from Figure 904 of some 40 centicycles or 3-1/2 nm.

As shown in Figure Ao2-1, during .Flight I-5 after sunset, a 70 minute flight ended with a 2 nm error which is partly attributable to a waypoint setting error of 0.9 nm and partly to the shift in the B-D measurement, The flights during the transition of Station A seemed less affected by diurnal shifts than by low S/N ratios and sudden phase anomalies or local interference even during high The short periods of transition for S/N ratio periods.

Stations Band D seemed to have. little detectable effect.

probably since their greatest change was at sunrise and not during these flights ° From the propagation correction. at sunset for Station C. it is seen that the change is regular and fairly gradual so that an hour long fligr.t might accrue ^^ }I most.

an error of about one tenth of a lane or a mile a ,i F l0$ - £ ^^ zE 9( .'^.

^^ „}

^^

9.3.3 5/N Variation ^: The most significant noise effect. during the diurnal tests in the Wallops area was occurrence of fluctation of the CDI needled This may have been due to many causes, but ` most likely local interference, This. fluctuation occurred durir^g the tr^^nsition of Station D, which is strongest and least noisy in t:e W^.11ops area. In addition, the weakest station (A) was very ^^:•^:^ang during the whole flight, An analysis of periods of weals S/N for the stations with special.

fr^cus on Station A shows no indic^.tion of diurnal noise . fluctuation.

Interference and S/1V Variations 9.4 A11 the flights in the Wallops and Snow Hill VOR area were directed toward determining the effects and levels of inte^.rference to Omega navigation for use during the upcoming A series of flights investigated differential Omega studies.

interference in the Boston area near transmitters, powerlines and plants o :,, 9.401 Expected Results Preliminary discussions T;ith Mr. Robert Moore of the G .FAA Omega flight evaluation section indicated an Omega inter- ^` -; .

^, ^Y!

^^ .4 ^, 'a ference anomaly in the Snow Hill VOR .area that was detected at altitudes from 3000 ft to 10,000 fto Further discussions with Mr. Paul P.ademacher of Dynell indicated that the VOR itself might be the source of interference, and that similar effects had been noted on Long Island and i.n southern Connecticut ° Commander Herbert and Mr, Robert Willems of the Coast Guard Omega Project Office revealed that some difficul- ty in Station A reception rLad been observed as far south as their Norfolk, Virginia monitor stationQ This was attributed to low station power output and the Greenland icecap shadow effect.

9.4.2 Interference Observed and Probable Causes Interference can be classified into three sources: internal to the test aircraft, near field (local anomaly), and far field (lightning). In addition, signal strength can be reduced by variations in the Greenland attenuation. shadow effect and low station power output° The most obvious interference source was the aircraft inverters powering the VHF radios, A 20 dB increase or decrease occurred in the observed S/N ratio whenever the.

radios were turned on or off, respectively, as can be seen.

in Figure A^2-2 at 18;31 (Event 3) and 18:34 (Event 4), and .

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in Figure Boo-8 (Event 1), In addition, when the radios were left on for along period of time, the S/N ratio improved at a of., a rate about 15 dB per hour for the first hour as shown in Figure Ao2-2 from 18:34 to 19:30 ESTo The C-band trans- ponder installed for radars tracking had no observable effect on S/N ratios and did not appEar to generate any interference.

' Near field interference sources were not so easy to distinguish. ThA effects of these were manifested by a series ^f CDI oscillations when flying along an A-B LOP.

These rapid CDI oscillations were of twc^ mile Magnitude and continued for several mi,nutes^ This made it more .difficult for the pilot to derive. heading change. information from the display. When the CDI did settle down, it did. so for only a few seconds before again fluctuating. For example, in Figure Ao4-1, each CDI spike in a group represents a minute or two of constant fluctuation.. This effect was most often noted near the. Wallops airport which was found to be the center of the disturbance patterno This effect was most probably .not due to poor station reception . since the S/N for Station A was 0 dB as Figure Ao4-2 . shows and there ratio was a noticeab7x^ lack of weak signal lights. It was most likely the FPS-],E^ tracking radar energy being detected by the.

ADF sense antenna (Refo 8).

Other regions where interference was encounter regularly included.: a broad area in central Connect: between Willimantic and r2iddletown where weak S/N and diffi- culties with track loss were observed, near the Madison VOR where the CDI and MTG would wander about. , and along the north coast of Long Island near Smithtown Bay where course bending and track loss occurred. It has been suggested that as stated in Section 904.1 these disturbances may be caused by the local VOR stations or other high frequency transmitters, 9.4.3 Variation with Altitude Two types of interference were tested for altitude effects: powerline noise and other local interference, and far field attenuationo Although no powerline noise was found at any altitude, the Wallops. local interference showed a :definite. altitude correlation. All fli^,n.ts over the Snow Hill VOR were in the vicinity of powerlineso In addition, powerline crossings were noted on other flights as they occurred. Surprisingly, no powerline interference was detected•, either as S/N degradation or as position indication error .. Only the local interference effects mentioned above were correlated with altitude. A comparison of Station A S/N ratios on Flights 2-6 (Figure 5.1-2) and 2-12 (Figure.

B.3-2) shows that the observed decrease in S/Td ratio over central Connecticut was less noticeable with. increased } altitude. Further, there was an absence of weak, signal r lights and path bending over the north coast of Long Island at higher altitudes.

Wallops radar interference was observed on Flights 1-8 and 1-9 at 3000 ft, weakly on Flight 1-1 at 5000 ft, .and not at all on Flight 1-3 at 10,000 ft (Figures A.1-1 and A.4-1).

On all of these flights, the aircraft was being tracked by the FPS-16 radar. Transponder operation was apparently not a contributing factor, as the interference was observed at ^OvU ft wish the transponder both on and. off.

9.4.4 Navigation Accuracy and Ea;se of Needle Following Two particular types of CDT fluctuations tirere observed on Wallops flights. On Flights 1-S and 1-9, considerable CDI fluctuations were observed, apparently due to local noise tmost pronounced in the ir^un.ediate vicinity of Wallops (Figure A.4-1). On Flight 1-F, fluctuations in t'ne CDT were observed, apparently due to weak signals from Station A (Figure Ao3-4). Flight I-22 displayed indicator noise attributable to weak Station A, In the Northeast, three w problems occurred affecting the CDI presentation: irregular jumps of about one mile due to lack of Station A received ^: _ .. <, phase stability, drift due to weak Station A S/T1 ratio, and.

land jumps. due either to interference or weak S/TJ ratio.

When strong S/N ratios were being received, the pilot. was required to make only small heading corrections to maintain a centered CDI but poorer S/N ratios often resulted in noisy CDI presentations. Under these circumstances the,perferred flying method was to maintain a constant heading, with long- term CDI changes corrected and short-term variations ignored.

This filtering increased pilot workload considerably over those levels required during quiet periods, Flighas 1-8 and 1-^ enco^^ntered very frequent,. rapid CDI oscillations for periods as 1^n.g as five minutes, with one second stable needle indications occurring only two or three times in the course o.f the oscillations. These . full scale to either oscillations were of approximately half side of center of the CDL. This oscillatory condition was worst on Flight 1-9, which surprisingly was the most accurate flight observed ° When the aircraft was flown over the initial reset point after an eighty minute night f]_ight, the Omega indication of return to the reset point and the visual observation coincided. as closely as could be determined at 1000 ft altitude, as shown in Figure E.4-1.

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On Flight 1-6 the Station A S/N ratio was extremely poor as shown in Figure Aa3-2. This led to fluctuations in both the CDI and the MTG display, presumably because phase lock was poorly maintained and the indicators displayed processed noise. The weak signal light did indicate the lack of adequate S/N ratio. However, even on flights with such noisy data, the pilot could navigate by flying a constant heading and waiting for the Omega. indicat:^ons to settle be- fore taking a position fix. Manual data filtering .was difficult during periods of turbulence and maneuvering, However, few Wallops flights were beset with such combing- tions.

Flight 1-22 displayed fluctuations on the CDI and MTG .which were noted on many other flights.. These fluctuations were regular, and approximately one mile in manitude. From flights parallel to LOPs, it was determined that these jumps are caused. by phase irregularities in the Station A signal.

These fluctuations were observed on other flights, but do not show up well_on the. plots because . the. data is o .condensed in time.

S/N.Variatons `9.40 5 As mentioned. above, the greatest variation in; S/N _, , ,^ _, ^, ^'i fi^ ratios. occurred with the turning on and off of the VHr radios onboard the aircraft. However, significant variations did occur in the Station A S/N ratio.

Deterioration in Station A S/N ratio could come from two sources: deterioration of signal strength „ andincrease in background noised If background noise were the cause of poor S/N ratio for Station A, denegration of other S/N ratios would also. be expecteda Since this was not always the case, it was concluded that the occasional ].ow S/N ratios for Station A were the result o^ low signal strength. at the transmitter, or greater than usual attenuation over the Greenland icecap. During several flights, attenuation presumably caused poor Station A S/N resulting in weak signal lights, poor phase tracking, which in turn resulted in lane jumps, CDI drifts, and. TfiTG jumps or failure to count. .Flights others exhibited these symptoms 1-6, 1-10, 1-23 and many coincident with poor Station A S/N ratio.

9.4.6 Ground Si a S/Y1 Comparison An analysis made. of strip chart CDI records for both the ground and airborne tests shows similar irregularities needle jumps both in length and magnitude, The ground or test data also showed a slowly shifting bias which was probably caused by interference from 50 Hz powerline fre- quency drft o The ground site S/N results compared well with the airborne data with the VHF radios off.

9.5 Precipitation Static Effects Two flights were conducted during periods of precip- itation near Wallops. One was flown during light to heavy rain, the other during light .snow showers. In the Northeast region, two flights encountered light snow storms and a third was under IFR in alternating moderate to heavy rain.

Expected Results 9.5. 1 The nature of^VLF reception with an E-field antenna, precipitation static can be expected in rain or snow and some types of smoke. As the vehicle flies through the precipitation, the particles ma^.cing and 'creaking contact with the aircraft skin can cause changes in the aircraft's.

E-field stronger than the Omega signal .detected between the E-field antenna and aircraft skin.. 'rhe extent of the static is a function of particle charge density and. the speed of penetration.

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9,.5.2. Description of Circumstances Flights through light snow showers lasted no more than five. minutes. Rain was encountered during Flight 1-21 (see Figures Ae5-1 and A.5-2). Alternating moderate to heavy rain occurred during the first twenty-five minutes followed intermittent light rain, with the second half of the by flight employing different LOPs to determine any effects on navigation. It can be seen that there was no appreciable precipitation effect at Wallops.

However, during. Flight 2-11, which was IF^2 in heavy rain, the first hour. was essentially static free (Figure but the second hour encountered heavy precipitation B.2-3) static from 1725 to 1746 EST,. during which phase tracking was lost. Figure Bo g -6 shows even Station D S/N w.as completely masked by the static effects.

S/N Variation 9.5.3 There s^ g ems to have been no noticeable effect from the since during the encounters, only Station A snow showers, appeared. even occasionally slightly degraded whereas the impairing effect on precipitation static should have had. an Flight 1-21 shows S/N ratios decreased during all stations° the values expected with the radio turned .off, the rain from ^ ,:_, a .

(Figure A.5-2). t4oreover, the S/N plots show irregular levels over short periods indicating that the precipitation effect varied rapidly but had only a minor overall influence especially when compared to the effect of turning the radios off at the beginning of the flight and back on at the end.

The S/N variation during heavy rain in the Northeast as noted above was a drop off in level of from 20 to 35 dB for Stations A and D respectively. The average S/N level was about 3 dB higher in the Northeast than in the Taallops area, but there was no observable difference in the ability of the receiver to navigate properly° Accuracy and Ease of Following Needle 905.4 During precipitation in the Wallops area there was no degradation of indicator information, although there was a CDI fluctuation ten minutes prior to entering the light snow shower which most likely is unrelated to the precipitation.

The position, waypoint and final destination accuracy was about average for the Wallops area. During the IFR flight in the Northeast, the first waypoint was indicated simultane- ously by both VHF and Omega, some 50 minutes into the flight and through some areas of very .heavy. rain. However, 15 minutes ater, the precipitation static completely obliter- aced the S/N for all stationG resulting in track loss.

r 9.6 Fli ghts Parallel to Lines of Position A series of flights were made parallel to LOPs. In flights along constant LOPs (listed in Table 9-7) the CDI defle^:ti^n;was assumed to depend on only one LOP, and hence incorporate the anomalies peculiar to only the two stations generating the LOP. These anomalies have been discussed.

aboveo In addition, flights along certain LOPs reflect the effective increase in noise due to poor geometry of the LOPS.

Flights LOPS 1-6 A -B 1-8 A-B, B-D 1-9 A-B, B -D 1 - 22 A-D, A - C, A-B, B - D, B-C 1 - 23 A- B, B - D 24 A - B, B - C,,C - D 1 - 2-13 B - D 2-31 A-B, B -D 2 -44 B-D Table 9-7 Flights Along LOPS ected Results

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Variations were expected in CDI noise observed flying u, „'..

^ ; ].2 0 ^^ f i i along the different LOPs, due to the different noise characteristics of each station, and due to different effects of local noise with each LOP choice. Because of the wide spacing of the C-D LOPs in the. Wallops area, difficulty was expected in flying the C-D LOPo 9.6.:2 Observed Results As discussed above, Station A S/N ratios were often not very good, The flights along and normal to LOPS employing Station A confirmed that Station A was responsible for noise in the CDI and MTG readoutso The C-D LOP was predictably hard to fly, ^: As discussed in Section 9.4, navigation with Station A encountered various local noise prienomena strong enough to .affect the phase measurements from Station A but not the.

i others. Station A S/Td was also prone to background noise effects. On Flight 1-22, turbulent air rnade the pilot's .job of filtering the CDI fluctuations more difficL^lt, as is evident from Figures A.6-1 and A.6-4o The apparent improve- went in needle following in the second part of the flight after 11.39 EDT was partly due to an increase in Station A S/N .ratio as the VHF radio power supplies warmed up, and partly due to an LOP change so that Station A signals were employed in only one LOP determination. The LOP change resulted in smoothing of the CDI, but the Z^ITG readout, heavily dependent upon the A-B LOP, was still noisy.

On Flight 1- a slow CDI drift to the left was 24, observed wk ► s^n flying the C-D LOP which was not correctable with aircraft maneuvering through large heading changes and path offsets. This is attributable to the 43 mile spacing of the C-D LOPs due to poor hyperbolic geometry near the extend- ed baseline as illustrated in Figure 3-30 On flights over central New Jersey and central Connect- icut when the Station A S/N was poor enough to cause indicator drift or lane jumps, it was found possible to fly along constant B-D LOPs. Earlier flight t`st programs,also indicated the relative ease of flying along constant LOPs (Ref . 29) .

9.7 Terrain Effects Aside from local disturbances near Wallops or the Madison VOR, only the central Connecticut and Thew Jersey areas produced any position correlated phase .anomalies.

Flights: over hilly or mountainous areas, cities, forests. or expanses of water revealed no additional phase anoma es or _ ^ -- - 1 _ _ _ - changes in S/N ratio.

9.7.1 Expected Results Due to the nature of propagation of VLF signals it was expected that local effects on phase or S/N would simply be too small to observe, as explained in Section 902. This was substantiated in previous flight test programs investigating use. of Omega signals in valleys wr^ere VOR signals were lost and the mountains produced no no^..iceable effect on Omega navigation information (Ref. 33)A 9.702. Observations over Cities, Water, Mountains and Forests It was anticipated that flying .over cities could adversely affect S/N ratios and in general degrade the navi- gaton performance due to local. interference from many sources. In the actual tests, however, no degradation was encountered with.. the exception of low-altitude flying along the Hudson River under the New York TCA which may not be correlated to location. The signal masking effect of local noise sources during flight below the New York skyline may have caused an increase in received local nose which increased the weak signal. light and decreased the S/N ratio {Figure B.3-4). Expected urban noise sources were television 12.3 ^ 1 1 f ^.

towers and powerlines which proved to have no observable effect.

There were no noted irregularities or changes in S/N ratio during flights over water. The areas investigated were: Long Island Sound, Delaware Bay;. the portions of Chesapeake Bay, Chincoteague Bay,aand Atlantic Ocean adjacent to the Wallops area, and the. New York Lower Bay bEtween New Jersey and Long Island, Four flights in the TZortheast Corridor were flown in the .vicinity of mountainous area;o Flights 2-7 and 2-21 were flown at low altitude around NYt. Washussett, which rises abruptly to an elevation of about 2000 ft MSL from the prevailing terrain elevation of 1000 ft. Flight 2-11 was flown at 7000 ft over mountainous terrain rising to 2300 ft MSL during the flight from Dulles airport to Bedford via. the Lake Henry VOR, This route was flown in IFR conditions including moderate to heavy rain, with extremely low Station A S-N patio and precipitation static resulting in loss of phase lock. Flight 2-51 was flown at 2500 ft into the val ey surrounding rat. Washington which rises to 6288 ft.

A lane dump was encountered once clear of the narrows valleys and in_open terrain north of the mountain. But flight within l24 several hundred feet of cliffs towering 3000 ft overhead encountered no signal loss or increase in weak signal lights..

Approximately one fifth of the Northeast Corridor fly- '^ ing was over unpopulated forest areas, There were no observable changes in navigation ability of the receiver attributable to forest area^o uver Effects 9.8 Mane Flights 2-7, 2-21 and 2-51 were specifically designed to determine what effect various maneuvers would have on Omega receiver performance. A series of stalls, spirals, steep and medium banked turns and rapid pitch up maneuvers were accomplished at various altitudes with no apparent effect .4n Omega presentation or S/N ration ^, _ _. _

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Section 1^ SUITABILITY OF LOW COST OMEGA FOR GENERAL AVIATION In order for any new navigation system to be considE_-ed suitable for introduction into use by .general aviation, two important considerations must be investigated: signal availability at all altitudes and weather conditions, and reliable accuracy. From the users' standpoint, two addition- al suitability requirements must be met: reduced pilot work- load to maintain safe flying conditions, and. current system status information as might be found in Notices to Airmen, 10.1 Signal Availability With the broad coverage of Omega, navigation signals should be available at least at all altitudes providing terrain clearance, With no radio horizon effects, the greater signal avail- . ability of Omega. would be advantageous for low-altitude maneuvering for approaches at airports where VOR coverage is poor. .Any strong source of interference could possibly result in a Local decrease in S/N ratios, with corresponding difficulties in maintaining phase lock, Although several occurr+^nces of local interference were suspected, none could verified by the S/N ratio plots. Sufficient experience be E was not obtained in this program to confirm local interfer- ence effects which may, in fact, be manifestations of the current experimental status of the Omega system.

r, The Station A S/N was sometimes too low along the Atlantic coast to be used for navigation. This is due to several causes low station power output (Norway isn't i expected to be at full power for some time), Greenland icecap attenuation (shadow effect), and anisotropy of atmospheric attenuation along east-west paths (the west traveling energy is attenuated 202 times more than the easterly, Ref, 6}, Experience from this flight test program indicated that the antenna system (coupler and ground circuits) installation is 1` critical to received. signal strength.

Finally, precipitation static can adversely affect even strong signals if E-field antennas are employed. Therefore, H-field loop antennas would be a requirement for IFR Omega use, 10.2 Observed Accuracy The observed accuracy of the Omega system fir the Northeast Corridor and Wallops area flights was duite sats-

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factory for enroute RNAV and most likely satisfactory for terminal operationso only nonprecision approach capability was investigated in the flight program.

but two errors. observed in the Omega. system read- A11 outs were less than t^^o miles, and most errors were less than one mile. This does not, of course, consider circumstances in which equipment failures were detected. These results compared well wa.th predicted accuracies. Table 10-1 shows a comparison of different types of Omega navigation and. their accuracies.

Expected Accuracy Source Mode 0,5 - 2.0 nm Swanson (Ref. 34) Simple Omega 0.25 - 0.5 Brogden (Ref , 35 Differential 0.3 - 1.5 Pierce (Ref. 9) Composite Swanson (Ref . 36 ) 0,75 - 3.0 Difference Frequency Table 10-1 Expected Omega Accuracy by Mode Overall Omega accuracy, however, can be a strong function of receiver design and local interference.- On the receiver used, waypoints could only be inserted with a resolution of a tenth of a lane, Thus, the results achieved f

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in this flight test can be considered a base case for general aviation Omega receivers, But even the most expensive systems are not immune to lane jumps (Ref. 37) A simple statistical analysis of radial errors. was done on a sample of 31 waypoints in the Northeast and Wallops regionso The sample mean was x = ,7/+ om and the standard deviation was Q = .77 nm.

10.3 Required Pilot Technique and Pi of Reaction As discussed in Section 9.4.2, two types of indicator fluctuations occurred, requiring the pilot to visually filter the: output in order to navigate smoothly. In the instance of a short term phase instability the pilot wo^ild simply change heading slowly using half standard rate turns (1-1/2° bank).

Indicator fluctuations in the Wallops area due to local inter- Terence were impossible to filter due to the. rapidity and magnitude^of fluctuations, and . the pilot was required to hold a heading for several minutes until a stable. CDI offset n- dication, could be obtained,. These latter fluctuations 'h:^d a period of about one second and magnitude of -^• 2 CDI dots (+ half scale or 2 nm}. Lt has been . shown that a pilot will.

tend. to lose confidence in his navigation system if he continuously observes random meter fluctuations due to noise greater than one fifth scale deflection (30 ua, of one dot) (Ref. 30). Greater accuracy and less susceptibility to short- term noise, can be expected from filters with time. constants on the order of two minutes, The lack of such a filter, how- ever, would necessitate incorporation of air data to provide lead for a usable display, Four pilots were employed in the course of these flight tests. Each filtered the CDI output at a different sensitiv- ity with heading. changes varying from 5° to 20° per dot on the. CDI, and using from 1/2 to 1-1/2 standard rate turns..

The lower change. rates tended to produce a smoother course.

Pilot reaction varied depending on the stability of the indicator readings and waypoint accuracy The range of re- action was from that of pure skepticism. as to the ultimate use of Omega for general aviation, to a guarded optimism that indicated a need for more receiver filtering and a blunder protection system to avoid incorrect wayponts during IFR operations, Need for Current System Status Information 10.4 Two forms of status information will be rewired by pilot users. One is a projection of station availability _ including output power levels and periods of outage published in Notices to Airmen for flight planning purposes. The other will be au augmentation of the weak signal light concept to include a steady light to indicate either a complete station outage, signal loss due to interference or computed LOP track loss.

Presently the only method of obtaining current detailed system status information is calling the Coast Guard Omega Navigation System Operations Detail (ONSOD), A reporting capability exists in the form of Notices to Mariners, but these reports are not very timely by mail. During a year's time of some 2600 notices, only 35 pertained to the Omega System, and only two system status and availability prognosis reports were made, Various forms of improved status reporting systems have been proposed.. A phase anomaly or station outage broadcast warning system for receivers has been proposed by Pierce (Ref. 6). It consists of changing an 11-1/3 Hz sideband modulation to 5-2/3 Hz on the 10.2 kHz carrier which would activate a warning circuit in the receiver, Amore immediate.

interim voice system to be used with. VHF receivers similar to Flight Service information is detailed in Appendix C. ` 13.1 __ ^ ^_ 10.5 Comparison of Omega Results with VOR/DME Results The FAA has developed a VOR route width standard of + 4 nm (up to 51 nm from the VOR, with a widening at + 4.5° beyond 51 nm) based on system use accuracy data ( Ref. 38)n Recent NAFEC flight tests have shown VLF navigation to be an acceptable system that will operate well within the 4 nm tol- erance (Ref . 39) .

A nonprecision approach standard based on VLF with minimums down to 400 ft and one mile has been proposed by Litchford (Refs 40)o This would decentralize major hub air- ports and VOR beacon facilities allowing considerable growth in RNAV airways where the VOR airways can Ue crime saturated.

A comparison of test flight statistics using Omega was made with previous data on the results of VOP./DMC RIvAV used for low altitude VTOL corridors in the Northeast Corridor (Ref. 2).• The VTOL VORTAC statistics are given in range and bearing error and the Omega in radial position error as shown in Table 10-Z .:_.^ VORTAC VORTAC Omega Bearing Range. Radial (deg) (nm) (nm) Ool -0.1 Mean .74 Standard 2.7 0.7 Deviation .77 Table 10-2 Comparison of 'JOP.TAC and Omega Waypoint Position Errors It can be seen from the above Table that Omega naviga- tion has a strong potential to augment VHF/tiHF systems, and can increase at low cost the enroute and terminal .area.

traff^^ density. But full. system operational status and ' availability as well as flight information are prerequisites before complete adapt^.tion for general aviation use.

^ 'I 1 t Section 11 COiV^CLUS IONS The conclusions derivable from t'ni,:, evaluation fall into four general categories. The categories that follow are. interference and diurnal variation effects, transmitter difficulties, airborne equipment, and user considerations, There was • no measurable effect on navigation. from flying very near coastlines, powerlines, television. transmitters, over urban areas, between mountains or during extensive air- craft maneuvers. There was no diurnal repetition of S/N variation and diurnal phase. shifts had only a minor effect on navigation accuracy, Local noise sources can have a signi^icant effect on navigation but have not been conclusively determined, Most likely VOR transmitters (e.g,, the Madison VOR) and some radar sites such as at Wallops affect the measured phase in the receiver. There is a noticeable. decrease in m?gnitude of thin effect with altitude, Day td day variations in S/N ratio were observed with all the Omega stations, but most predominantly with the t _ -- .

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Norway station S/N in the [^1a11ops area. The Station A S%N varied from very strong to unusably weak during a single day, Since station coverage is limited and only five stations are operating, Station A is critical to good LOP geometry in the northeast United States o A need for more frequent Notices to Mariners or inclusion of Omega information in Notices to Airmen has been demonstrated.

Receiver operation was satisfactory and provided high accuracy when S/T1 ratios were moderate to good, The cost and accuracy compare well with the VORTAC system. Currently, ground computation is necessary for flight planning, but new waypoints can be approximated enroute with little loss of accuracy if LOPs are plotted on charts beforehand.. Waypoint blunders, however, are readily made and a need for some type of blunder detection in waypoint selection was determined, An extra LOP tracking. loop would enhance the navigation reliability by allowing the pilot or an automatic circuit to switch when one of the currently used LOP pair stations fails, or Lecomes unusably weak.. ` ^ Antenna and receiver installation are critical to good.

μ especially if the aircraft i^ equipped with signal reception, AC inventors. For this reason the VHF transceivers had to DG -' 13 5 i t _ the greatest effect on the S/N ratios of any interference.

For IFR operation it is probable that an H-field loop antenna will be necessary since the E-field wire is strongly suscept- ible to precipitation statics The pilot's workload during long enrou^e waypoints was considerably reduced from the comparable VOR navigation, but with waypoints spaced closer than ten miles apart the work- load become heavyo During periods of local interference the pilot was required to visually filter the CDI output and occasionally fly compass headings with infrequent CDI updateso Pilot reaction to the system's use ranged from strong pessimism to a guarded optimism.^caith qualificationso The Omega system as it exists is not one which allows the pilot to begin use. enroute without an accurate position fix, and care must be taken in the choice of LOP pairs to maintain the optimum geometry for reliable navigation, However, it does provide increased user freedom, safety, ,and economy by allowing. direct routing . rather than beacon .flying., Finally, the system. will be found to be suitable .for continuous coverage inexpensive area naivgation, especially t„7here VHF coverage is not available.

1 __ m Section 12 RECOI^'II^IENDA.T IONS The following recommendations are given from insight gained during flight testing. . They are grouped by additional flight testing, equipment modification, and system improve- ments, Additional flight tests would be useful to determine areas of encountered VHF interference, and these could be charted as VLF warning areas orr appropriate NOS publications for airmen. Further flight tests would determine position filtering parameters appropriate to en.route and approach portions of the flight profile.

Development of a dead reckoner or additional LOP track- ing loop is needed for aviation users who might experience Cemporary signal loss, Automated filtering will be required for commercial low cost receivers, along with a blunder de- tection^;aarning system and a receiver operational status feedback. to the pilot.

Effort should be Wade to expedite implementation of an ,t Automated broar^;;ast reporting techniques should be refined and implemented when available. ^ffoXt also shauld be made to expedite the full eight station operation at full power to provide the necessary coverage and signal redundancy.

Area navigation enroute and terminal standards should be designed to minimize waypoint ambiguity and workload. Final- ly, it is highly desirable that the National Ocean Survey prepare aeronautical charts (enroute and sectional) with LOPs from three stations oiz a chart printed in one tenth lane increments (e.g., a New York sectional with A-B, B-D and A-D pairs, or A-B, B-C and A-C pairs) for ease in flight planning and enroute course changes.

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I Appendix A t WALLOPS AREA FLIGHT TESTS Organization cif Flight Test Ap^^endices A test description page is^ included for each flight in the Wallop.`- area in Appendix A and each flight in the North- east Region in Appendix B, In addition, for a selected sample of flights which are referred to in the text flight data pages are included.

The first flight d^^.ta page includes the Omega indicator data which are readouts of miles to go (MTG) plotted on a scale of 0 to 75 miles, four status flags and the left right needle deflectioiz (CDI) as described in Section 8.3 The four status flags are a bistable to/from. indicator, au^oGG^^ a^;t- ivation, reset of lane accumulators, ar_d weak signal light activation in the past ten seconds ° Event mark num^er changes are plotted along t.ze x-axis ° Time is labeled every ten minutese.

Following the Miles to Go and Needle Deflection page are two pages of S/N ratio for Stations A, B, C, and D which derive time axis and event markers from the same. data as MTG y ..

_ _ 1 _ J ^, _ and CDIo The location and description information on the M'TG and CDI page are ab'^reviated for completeness and are encoded according to the Glossary and the following conventions: ,, .

Wsl A Weak signal light. observed during Station A transmission period T/0 WAL Takeoff from Wallops airport Omega indication of waypoint 1 (from flag, Wpt 1: Omega needle centered and NITG zera)o VOR indication of waypoint 1 Wpt 1: VOR Visual indication of waypoint 1 Wpt 1

AZ 2 CDI is autozeroed (symbol. used only when more

than two minutes elapse between waypoint and autozero) Crossing a coastline for land to water Coast L-W Visual position report of 7 nm to the south 7 SSE WAL southeast of Wallops airport Visually 1 nm northwest of tower with charted 1 TJtn1 twr 229 ' height of 22.9 ft above MSL.

;; W ;; E, t ^t u 140 ^, ,^ TEST DESCRIPTION Flight Tdo, 1-0 u TEST OBJECTIVES: Provide initial view of S/N ratios in the Snow Hill VOR area. First in a series of flights between Salisbury and LJallops past the Snow Hi11 VOR providing local inter- ference data at various altitudes, Check point to point accuracy, 19 Feburary 1975 DA'TL.: TIME : 1546 - 1601 EST O ORIGIN: Salisbury DESTINATIOII; Wallops Via Snow Hi11 VOR ROUTE: ALTITUDE: 1500 ft.

VFR, 15 kts , SW tidEATHER: SUMMARY: First flight in the Snow Hill -Wallops area, initially along powerlines running Flew within one south from Salsburyo -s F mile of the Snow Hi11 VOR^ Recorded data not reproduced.

L i E k' 'r TEST DESCRIPTION Flight T1o. 1-1 TEST OBJECTIVES: Provide initial. area survey of Wallops and mid Delmarva Peninsula at 5000 ft, and selected. lower altitudes with radar track- . ing, to determine coast effect, level of accuracy achievable, and location and magnitude of interference.

DATE: 20 February 1975 TIME 1020 - 1222 EST ORIGIN: Wallops DESTINATIOI7: Wallops Low altitude star ROUTE ALTITUDE: 5000 ft a - 2000 ft a VFR, 15 kts, NW WEATHER: SUMMARY:. Star route flown with radar tracking at 5000, 4000, 3000 and . 2000 ft, Initial circuit flown at 5000 .fto was: Wallops, Parksley (Wpt 1), Wallops Coast Guard (Wpt 2), Pocomoke (Wpt 3), Metomkin Island (Wpt 4), Saxis (Wpt 5), Chincoteague ..^.` Flight. No. 1-1 (con't) SUNQ•7A.RY: Refuge (Wpt 6) , Snow Hill VAR (Wpt 7) , and.

Wallops airporte Then on the second circuit each successive leg was flown 1000 ft^ lower. The data is divided into the first 62 minutes and the last 58 minuteso __ .

'it ^r • • Tape change • ^ 1123 Inner coast L-W W 2 1/2 N Horntown {{ {f k, . Wpt 5: omega - p 1113- p C-band transponder off y _ 15 15 C-band transponder on CDI = -1-1/2 dot fluctuation • C-band transponder off< ^ 13 1--- 13 AZ 5 Inner coast W-L 1 SE Wpt 4, Wpt 4; Omega ;': 12 a _ 12 Wp t 4 a - 11 ^ 1 ] 03 _ ] ] 3 SE Bloxom, coast L-W, - ` Wsl A j "' Wsl A S - .. i 10 C 10 Radar detectable as static '..

Tape change on VHF ^ - 9 1052-- - 9 Wpt 3 . Omega ^ ^ - 8 2SEPocomoke owerline p Abeam SWL VOR' •'• -^ - a ^ 6 Inner coast W-L

i

- ^ 'Wpt 2, AZ 3, Wsl A _ 5 '^' 1042- 5 3 NE Wpt 2, Wpt 2: Omega • ^- 1 NW Wp t 2, [ds 1 A 3 Coast L-W, Wsl A, 7S WAL -^..

• ^ - 1 ',.

-r 2 ^. Parksley, radar mark, Wsl A i'^^5T2- - Wpt 1: Omega • .^ _..,.^ Changed LOP input, then corrected back to original ^ Ws1 A - ' ^ Wsl A ! T/0 WAL, WsT A Right 75 SO 25 0 tf a r w Left t MTG Flags Needle Deflection • Flight 1-1 . (Fart 1) Miles to Go and Needle Deflection.

Figure A.1-1 •^ ^ • 1123 `^ 1123..

^^"' ^ ^^ `^a .^ ^ ^^" ^' ,^ 1113 ^^^ = 0 ^•^"' °--' -13 ^ ^ 13 :^ .: y •12 ' 12 ~^ 11 .03 •'--^..^....

1103` 11 •'^- 11 .::.^ ray.

:.:^^....

^-----^^ K,t- '" .. 1052 9 q ^^...^. 6 ,,..- . _ ^ 6 _,.,._, - ^.: .__:.^^ 5 =2 "^ d .. ., ir.....

ros'' - - ..

Y "+^-- 1032 r ^'- ^ 1032 ^ EST :;.^_ EST ';' ^_„^.

fir., ! ^ ^w^ .n •w•^ .'^^y ^.r ^b1 • ~^' •^'S^ ^..^,' ^+nr^s ^yye t^ 4 -10 -20 -30 +a o -lo - 2 0 -30 5/T^ Station A (dB) S/N Station B (dB) Figure A.l-2 Flight 1-1 (Part 1) S/N St^.tions A ^.ad B . _.I.__ l _ ^ 1 __ t^ 4• ' 1123 s^ 2 y • ^^ • ^^ s ^ 1 .^^,.^._ 1 •^,^,,,-^,,,,, .- „^^— 0 '^^•^-- 15 1d :'_- - 14 ^ .-? 13 13 ^ ; /^ b ^ ^^ 1103. • .,,^ = 1103" ..1)

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•^^ 2 2 3 1 0 p 3 2"^ , 1t'i32 F';^^ ST `~ _ c5T ..^.^ 4wi.

^« ^^— ^^ and Z 10 0 -10 -20 -30 0 TO -10 -20 -30 S/N Station C (dB) S/I^ Station D (dB) figure A.1-,3 Flight 1-1 (Part 1) S/N Stations C and D r ^^ ^ --^ _ „ - ^ - ^ ; Rny 10-28 abeam twr u - ', Land WAL Apr end my 28 - 5 ;^ 2 N apr end my 28 WAL.

4 Powerline ^^ ^^ ' 1216 AZ WAL , 3 2 N SWL VOR ti • 2 Pocomoke, Wpt 3: Omega, 2000 ft.

t ^ : 1 1206 Horntown i 1 E apr end my 28 WAL, w Wsl A •---^ 15 2 E Wp t 2, AZ 3 ^;" Descend to 3000 ft.

2 E Wpt 2, Wpt 2: Omega 1155- Wpt 2 ]2 12 Island missile site, coast.

• L=^d, noisy CDI, many ^' ^ anomalies - 11 1/2 SW Wpt 1, Wpt l: Omega Resume radar tracking 1145- ! Mild turbulence Scud clouds at 4000 ft ., - Radar tracking halted Apr end my 28 WAL, 4000 ft.

's, i • SWL, AZ 8 X135- 8 ....

SWL, Wpt 7: Omega ESl` ' , _ ? 1 ner cc-ast W-L n7 r <- Wpt 6, coast L-W r ^ ^ ^

' 4 Time mark (1126:22)

_ 75 SO 0 tf o tw Right Left ^Jeedle Deflection Flags MTG r{ >ilight 1-1 (Part 2) )`files to Go and Needle Deflection - Figure Aa-4 c' ,, f;; ^: ^_ 1.47 `: ^` ,.

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^.^^— 1216 ^T.a- 1216 ,, ^r4^ • ^^ 3 ^' ."^ • ^^A s a . ` ^ ^^Y 1 ^^^^ 1 1206 C-^ 1206 1 r ^•'' p ^ -^;— .a» ^:: ^^ s ;," —i5 ^ 15 ^ ^:.

^ _;^- — 14 • 14 ,,^,e.....1155 !

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^; —12 ^^ r^ "^, %^ :.'^.

.x ::-^ ^+ y, •=e^ i 1 ^.^ `^ 114S 1145 ;.:,.

-^* mac:. ^,^ ti^ ^^ ^ ^ r.

'' 1135--..8 ]135 g ,, ^ EST ^- ,,,,....,.,EST ^^;- ' ^^ ^ ^,= . .^ ^ 6 ::^ 6 ,...^, ^ ^^.^ --^,..— 5 w°.,^ i0 0 -10 -20 —30 0 10 10 -20 -30 S/t1 Station A (siB) S/N Station B (dB)

:Figure A^1-5

r?^ght 1- 1 (Part 2) ^/N Stations. A and B

14a ^^ ^^ ^ . ^- ,...- -^ .

..

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a ^ i r ---^ ^,•. ;-,., 1216 — ' •.^.^.

.^-- ^ ^'^• 4 2 s ^ - 2 ^ 1206 1206 °.^awr+. 1 ^^^ • ,,:^ r r ,, ^_': :^` iS ^ 'i^ }' 1155.

^^ ^'^ { 12 ^ ' ^ ` {a :` { 7v ; ?..^.^.

11 ^^ —I 1 -^^ 1145 ` ' _ ^ S ^. y ^'^ y + h ^ ^.—.

^ g .1135- •^^_,,,^ — 8 ^^trs.— ,^ =^- EST ESl' C.^„ ,.^...

^ ^ ^ ,,^• 6 ^ 6 ^?

`^ :^., ..^ 0 —20 -30 0 -30 10 — 10 10 —10 —20 ^1 i,: - S/N Station C (dB) S/N Station D (dB) ^.

Fright 1- i (Part 2) S/N Sta.ti.ons C and D

Figure. A,1-6

h i i.

' ^ ► TEST DESCRIPTION Flight No, 1-2 TEST OBJECTIVESc Obtain additional S/N data near Snow Hill VORo Second flight past the Snow Hill VOR and powerlines to Salisbury at low aJ_titude to investigate interference and accuracy DATE: 20 February 1975 1259 - 1320 EST TIME: Wallops ORIGIN Salisbury DESTINATION: Via Snow Hill VOR ROUTE: 1000 ft, ALTITUDE: VFR, 15 kts, NW WEATHER: Flight along powerlines from Wallops to SUMMARY:.

Salisbury for refueling.

1 ^

TEST DESCRIPTION Flight 1-3 TEST OBJECTIVES: Obtain S/N plot of Wallops area at 10,000 ft. with branches to decreasing altitude as radar coverage allows (includes return. trip from Salisbury).

DATE: 20 Feburary 1975 TIME: 1359 - 1617 EST t j ` ORIGIN : Salisbury DESTINATION: Wallops ROUTE: High altitude star pattern 3i 10,000 ft, ^! ALTITUDE: }; VFR with clouds at 4000 ft broken to WEATHER: scattered SUMr^lARY Flight made at 10,000 ft detected coast effecto Route of flight was Salisbury, Ocean City (Wpt 1.), Crisfield (Wpt 2) Hog Island {Wpt 4), Snow Hill VOPi (Wpt 5), Watts Island. (Wpt 7), Wallops (Wpt 8).

Some noticeable effect of local inter- ` ference on CDI, 2k ?^ ^4

am_

^ !

' TEST DESCRIPTION Flight No > 1-4 TEST OBJECTIVES: Check oint to int p po accuracy during transition, Obtain additional S/I1 ratio data for the southern Delmarva Peninsula.

20 February 1975 DATE: TIME : 1651 - 1740 EST ORhGIN: Wallops DESTINATION: Norfolk ROUTE: Via railroad to Kellam, along Bay Bridge to Norfolk 1500 ft.

ALTITUDE: VFR, 15 kts, WEATHER: SW Incorrect waypoint set in to New Church.

SUMMARY: No interference from powerlines along railroad. Incorrect waypoint for Norfolk, • .Sunset after landing, Coast effect observed leaving Delmarva Peninsula and approaching Norfolk coast.

^^ _, TEST DESCRIPTION Flight Noo 1-5 TEST OBJECTIVES: Obtain S/N data, point to point accuracy at night, and attempt to detect coast effects, during Station D transition periods, 20 February 1975 DATE: 1818 - 1932 EST TIME Norfolk ORIGIN: Wallops DESTINATION: Via Me"lfa, Tangier Island and Salisbury ROUTE: 3000 ft o ALTITUDE: Night VFR, 10 kts, S WEATHER: Used radio and visual beacons for a check SUNII^IARY : of night accuracy of Omegao Flight route was Norfolk: direct to Cape Charles VOR (Wpt 1), direct Melfa NDB and beacon (Wpt 2), direct Tangier NDB and beacon (Wpt 3), direct Salisbury VOR and beacon (Wpt 4), direct Wallops (Wpt 5)0 X53 ^ } l ^ _.

^ `i • • a F ,_.. 0 Tape off •-----._..^. -• --- ^ `i ^ ^ - 1- 4 ^.. 4 2 SE Wpt 5, Wpt 5: Omega ^^ 3 2 Tape change, 2 WSW SWL 1 1 3 E Pocomoke ' 'i 920 0 1SWpt4, AZ5 - © ^ n 15 1 W Wpt 4, Wpt 4: Omega F ^_ 2 E Princess ^'^nn, Wsl A 14 14 1 S Princess Ann, rr int .Coast W-L 13 Abeam Crisfield apt 12 2 N Crisfield, coast W-L-W ^ 1900 - 11 ..^- 11 Wpt 3: Omega and visual ' 10 ^ 10 Time mark, 3 SE Wpt 3 9 Outer coast L-W, Tape change 9. '' • - ^ 8 Wpt 2: Omega and visual .

$ ^^ Ws1 A 7 ^. 7 1 W Exmore 1$39. 6 1 W Nassawadox, 1 rt course ^ _ Ws1 A 5 Wpt 1: Omega and VOR - ^, 4 COb1/NAV ^, on 4 ?

3 COM/NAVS off ` EST ^^ .

- Ws l .A __ ': . - 2 ^ + 2 R/T to ORF J- 1 Tape change 1 ^ 1i t ^ - ^ 1 L_1 ^ 1 _.L..1 T/0 ORF, Wsl A 75 50 25 0 t f a rw Right Left Needle Deflection ^ • MTG Flags Figure A.2-? Flight 1-5 Miles to Go and Needle Deflection ..

z ^; .^ ^' I!

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^, ^.

•---^ - IL { ^Tw 1 ., "{ •- ^^ T.^.

= ^^ "; ^- ^` 2 ^' ^ 1 ^^ 1920 °""""' 1^ 1920 ^.

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': 1910 ^_^10 - 14 ^ y rA ^^ ti .^_ C.:^ ti i^ . R^, = 5^„ 13 ^ " 13 ""^= ^ 2 ^":^^ ^,, a_ ya- 1900 —^ _ RIF • r ~— 1 1 ^•^ ^r^^ ti to }: ^ 10 - •^^ r , ^^: 1849 ^•' 1849 9 ^ ^'^ ^ • 8 ^^^- 7 .::^ ,_,...., -" ^` ^ 1839 - f`'- 3.i y-- 5 5 ^^ !., _ • ^ s t ' ^^ i- -": 1829 =a;''^--EST ` ^- E ST • y_,.

10 0 -10 -20 -30 10 0 -10 -20 -30 S/N Station B ;dB) ^^ S/N Station A (dB) kcr ,^ and B S/N Stations A ,Flight 1-5 Figure A.2-2 ,' _155 ^; i __ ._r._...^.

0 0

T ^ 4 '7^ ^ 4

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#,^.,, ^ 1 1 1920 ^ 1.920 1 ^ ^; 15 - M^,....

T 910 .'^ -''^ ^^s : ^ 1'0" -^. _ ^z 1900 12 "^ .^;3- .,' 10 ^^ ^ .,• 9 ^^ 1849 9 Gl ^- ^•^ 7 _ri b ^^-- ] 839 ^;^ 1839 ^^ w ^^ ^ •_ 3 ^— 1829 ,^ EST EST -^^ '^7 ^' r; 10 0 -10 -20 -30 10 0 -10 -20 -30 D (dB) S/N Station (dB) S/N Station. C S/N Stations C and D Ao2-3 Flight l-5 Figure _._,, `i ^.

^.

TEST DESCRIPTION Flight Noq 1- 6 TEST OBJECTIVES: Provide initial mapping of S/N in Wallops area. at low altitude by flying constant A-P lanes from 20 miles south of Wallops to 20 miles northo Test magnitude and direction of coast effects, 21 February 1975 TiATE: 1035 - 1320 EST TIME: ORIGIN Wallops 1.

DESTINATION: Salisbury Modified east-west snake route along the ROUTE: Delmarva Peninsula ALTITUDE: 2000 ft.

VFR, 15 kts, SW WEATHER: Flight wa:^ rnad.fied anr_oute due to SUMMARY: difficulty of obtaining station A signal.

Lane count was lost 4 times. Various LOP .input changes are indicated and course numbers ps:rallel to the A-B LGP {200 and 600) were flowno ^^ i ^--•_ .— Crisfield coast. W-L-W 10 ^ 10 ^.

r ^.

9 9 Saxis inner coast L-W g 1 S New ChureH rr ' g 1153 ^ ^ -- 7 7 WAL, Reset, AB = O, BD=+2 • 6 6 3 S WAL

-c^^ AZ WAL

= 5 -^` 1S twr 264 4 ^°"' 1143 4 1/2 S Bloxom, rr 3 3 Hopkins inner coast W-L AB=.6, BD=-1.3 Hopkins coast W-L ^' 2 2 Tape change ^ 1132 Wsl A i ^" _-.., 1 BD =+1.7 ^ 0 ^, 0 1 N Onancock ^ 15 ^ 15 1 S Isthmus = 14 14 BD=-.3, CN=600 ,^.--^^^^^^ 1122 13 -^,^ AB=- 1.2, AZ ! 12. :' 12 Wachapreague coast L-W BD=-2.3 _ .^^ - ^ ll 11 Melfa, Wsl A ^ - ^ AZ Melfa, Ws1 A ^ 4 W Hacksneck, Wsl A, W-L ^ 10 -^ 10 3 W Crdkvl, coast L-W 9 9 Tape Change, Ws1 A ^- ^ Set BD=-7.3.3, CN=600 ""^D58 __ 7 ^'--^^ ^ 7 Set AB=+1.8, BD=-.3 ^ ^ 6 6 Ws1 A, 2 SE iielfa 5 Onancock road bend 4 4 5 Parksley, Wsl A 104$ Z Bloxom = 3 ^? 'EST 3 Ws1 A 2 2 New Church rr, 2000 ft _ ^` ^ 0 T / 0 WAL 4t f arw Right deft 75 50 25 Flags Needle Deflection ' MTG Figure A.3-1 Flight 1-6 (Part 1) Miles to Go and Needle Deflection _:'s _ _ ^ ^ ^, s ^: .

-^— '^ - ^`' ^^ ^ ^' 1203 .,^.•.;:a ^' ' s ^--^ `^, ^^. -;,.^ -E:-..^..^^ .,^: ^ - ^. '^'.^- ..,.

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T i 10 -10 -20 -30 i0 0 -10 -20 -30 S/N StatiorA A (dB) S/N Station B (dB)

3-2

Figure A. Fight 1-b

(Part 1) S /I1 Sta ions

A and B 1203 -

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10 0 -10 -20 -30 10 0 -10 -20 -30 S/N Station C (dB) S/N Station D (dB) Figure A.3-3 Flight 1-6 (Part 1) S/N S tations G and D x 1 Land Salisbury is • Tape stopped s' ,, i 1313 ' 8 ^ ^ 8 3 N Nanticoke ^.

• , } AB=-.4 BD=f2.6 ^ ?

c303 ^- 7 3 SW bishops Dead.

n AB=.2, BD=4.6 6 5E Princess Anrf ^ 6 f Princess Ann _ Wsl A s 5 Powerline SBY-WAL ..

AB=.2, BD=3.6 ` 4 2 NE Snow Hill, rr Tape change t 1238 5 S Ocean City,. 2 E coast • '_' 1 1 is n =' 0 Duter coast, 13 E SWL VOR 15 15 Inner coast L-W r ^ Wpt SWL: Omega and VOR 14 14 Added 1 AB lane at St^TL VOR ^- ;` ^= ^ ` 1218 Z°-= ^ EST Jumped an AB lane • Wsl A rr, CDI fluctuates, =' 12 12 Crisfield coast W-L ^_ ^ ^ ^ ^ ^ 11 11 1 E Smith. Island 75 50 25 0 t f a r w Needle Deflection MTG Flags Go and Needle Deflection l-6 {Part 2) Miles to Figure Ao3- 4 Flight .

• • 1313 _^ --¢^ 8 8 ^ ^ .

...a.- 1303 --^- ^^ 7 i 303 - ^ 1253 r ^• --_..`:, ^^ -'^, . ^^ ^^ .^.._.., ..^ ._^-- tea.

• 4 1238 ^^ -^,....` 1 - 1 ^ R. ^ ^..: o . •. ^ ^.

^.

_,^ ^, ^^— ^^ 0 ^ 0 1228 -• ,^^ 122$ ...

_ 1218 ^^' s ^ EST -w^••^---._, _,.w,,;^J ^-,. EST ^^^ ^ ^ • ^^ ...." 13 .^ .,,, —._.,.,^ „..^ ^,^ -12 .^ `^_`„ 0 -10 -20 -30 10 0 -10 -20 -30 /N Station B (dB) S/N Station A (dB) S A and B Figure Ao3-5 Flight l-6 (Part 2) S/N Stations i _ _ ^ B 1303 ^ ^ 1303 •^ b l 2.53 ^oZa -^ 0 ^^ 1228 ^ 15 "'^ ^ 1218 fST EST p - ' ^ 13 13 • ^ .^L ^ i -^, ' i ' .---^ 1l 10 4 -10 -20 -30 )0 0 -10 -20 -30 " S/N Station C (dB) S/N Station D (dB) Figure Ao3-6 Flight 1-6 (Part 2) S/N Stations C and D • , ^ ^ ^ __ TEST DESCRIPTION Flight No, 1-7 TEST OBJECTIVES: Point to point accuracy cheek through Snow Hill VOR areao Third in a series of flights between Wallops, Snow Hill VOR and Salisburyo 21 February 1975 DATE: 1412 - 1432 EST TIME Salisbury ORIGIN: Wallops DESTINATION: Via Snow Hill VOP,. and powerlines ROUTE: ALTITUDE: 2000 ft.

WEATHER VFR, 15 kts, SW

First two thirds of recorded data lost d^ae

SUN1t^ARY: to improper jack input, Data was begun near Snow Hi11 VOR 14 minutes after take- off from Salisbury.

3.64 _1_ , ;^ TEST DESCRIPTION Flight No, 1-3 TEST OBJECTIVES: Initial check of LOP sensitivity with radar coverage along constant A-B and B-D LOPs. This flight. to be repeated after sunset (Flight 1-9) and both. will invest-

igate interference in the Snow ^^fill VOR

and 6Jallops areas, coast effects along

different LOPS, maneuver effects. Radar coverage will be provided by the Wallops airport FPS-16 tracking radar DATE: 21 Feburary 1975

TI*.dE s 1624 - 1750 EST

ORIGIN: Wallops DESTINATION: GIallops ROUTE: Race track ALTITUDE: 3000 ft.

t^TEATHER: VFR, calm

Moderate amount of difficulty in needle SUMMARY: following caused by rapid CDI oscillations due to local interference (radar), __ Flight No. 1-8 (Con't} SCJNIMAP.Y Oscillations lasted two to five minutes each with breaks in between from ten to thirty seconds, Radar calibration was made at reference point GJE 1000 (. 1000 ft- east of the west end of runway 10 -28 at Wallops) before and after flight.

TEST OBJECTIVES: Provide same information as Flight 1-8 but conducted at night with C-band transponder on.

T^ATE: 21 Fel:ruary 1975

t

TIME: 1810 ^- 1935

ORIGIN: Wa1J ops $^

DESTINATIOPI: Wallops ;; Race track ROUTE: 3000 f t .

ALTITZJDE : VFR, calm WEATHER:.

Same as Flight 1-s except more severe SUMI^ ? ARY; oscillations in CDIo Final return over reset point. (WE 1.000) at 1000 ft was as exact as can he determined visually (within 100 ft) , _ .- - 10 ^'; ^ Laid Wallops h WE 1000 9 9 --^y't. 1930 8 8 C-band off JJJ Tape change 7 7 . 6 b ,-_, ,^,^ 2 W WAL, CDI fluctuating 3 E Hopkins ^ 5 4 ' 4 Coast L-W s_.'

3 SWL VOR 2 Greenbackville, start turn 1 ^^ 1 1 W Wallops ' 0 ^ . 0 Inner coast, turn for SWL VOR 1900 - ':^, ^- 5 SW Saxis, turn for E leg . I5 -15 14 14 Tape change 2 S Saxis ' 12 - {~ ^-^g^0- 12 3 SE WAL, Inner coast W-L - ^ ^ CDI hard to fol^.^w ` '^'^_ Noisy CDI i_ .

Outer coast, turn l t ^ ^ ,^^ 11 CDI fluctuations 8d0 ='^ - 1 ^ '= =-{ 19 - 2 SE Wallops CG, turn W 1 S tJallops CG ^S Wallops Is radar site 8 8 x° 7 Bloxom rr A 7 b Coast W-L S .. 5 1 SW Saxis, coast L-W ' 4 4 Tape change x 3 ^ 3 Inner coast 220p _ 2 18ES T - 2 Hallwood rr CDI oscillations, hard to u ^----- ^!

;^ follow ^ . - 1 ^^;, ^ Begin W leg 1 WE 1000, T/0 WAL my 10 t ! t L L=.t < < ^' 75 50 25 0 t f a r w Right Left .

r MTG Flags Needle Deflection and Needle Deflection '' Figure Flight l-9 Miles to Go A.4-1 16^ +.

i 930. ^ . ^=^r-=^ 9

^ ^--

1930 9

- 8 ^

6 . 6 ^: ^

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t.- ^^ 1850 =.. ^ l^ - 12 r ^: dy `d 1840 .^- r 8 g ^,: '- .. ^ ^` 7 ^w --R''^. 1.830 - 1830 ^ ^' S :;^ i^" 1820 ' ^ ^ 1820 ^- ^°' EST 2 EST ^} .

1^ -..

-;.,, ^;^ 10 0 -10 -20 -30 10 0 -10 -20 -30 S/N (Station Fr (dB) Stration A (dB) S/N and B Flight 1-9 S/N Stations A Figure A,4^-2 ^;

___ _ }

10 ^^ 1930 ^= ^ ^^ 7 7 }.^^ 6 ^^ '^•' 1920 5 %'^""' .^

rp^ 2 2

1910 1 ^•^'^"—' 1910 1

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1850 ^ 1850 •-r _ .- 12 12 :t r ^• ♦ T P°

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t.r^ ^ .1 ^ 10 0 -10 -20 -30 0 10 -10 -20 -30 S/N Station C (dB) S/N Station D (dB) Flight 1-9 S/N Stations C and D Figure A,4-3 .

. 170 at ... 1 -^ : ^ TEST DESCRIPTION Flight No. 1-10 TEST OBJECTIVES: Provide additional S/N ratio data. and accuracy information in Snow Hill VOR area by flying VOR radials and comparing with Omega results, including use of the.

course number function.

DATE: 22 February 1975 TIME: 1140 - 1250 EST ORIGIN: GJallops DESTINATION: Salisbury ROUTE: Snow Hill VOP., constant 120° radial ALTITUDE: 6000, 500, 4000, 3000, 2000 fto WEATHER: VFR, 10 kts, SW SUMMARY: Flights along the 120° Snow Hill VOR • radial were made at various altitudes to investigate coastline and interference effects at various altitudes. Consider- able coast effect was evident in Omega indicator .and considerable scalloping in VOR at lower altitudes.

I I I ^^

TEST .DESCRIPTION Flight No, 1-20 TEST OBSECTIVES: Provide initial S/N data along powerlines `' • and in vicinity of Snow Hill VOR for the second series of Wallops flights, 7 NIar ch 19 7 5 DATE : 1355 - 1+15 EDT TIME: Salisbury ORIGIN: Wallops DESTINATION: Via Snow Hill VOR ROUTE: 2000 ft, ALTITUDE; VFR, 10 kts, S WEATHER: Determined CIU difficulty enroute and SUMMARY: recorded last two thirds of flight. Used A-C and B-D LOP pairs.

— --^^ TEST DESCRIPTION

Flight. No. 1 -21

Obtain S/N data in precipitation (rain), TEST 08JECTIVES: test results of precipitation on accuracy in the Wallops area, Use different LOP pairs for comparison.

DATE: 7 t^iarch 1975

TIME: 1613 - 1722 ED'.0

ORIGIN : tJal lop s DESTINATION: Salisbury ROUTE: New Church, Kellam (Via railroad) ALTITUDE: 1000 fte Tn1EATHER Alternating moderate and heavy rain Flight in heavy rain showers produced no SUMMARY: observable degradation of S/N ratio or difficulties in navigation. Voice tape

for second ^ia1.f of fligh was lost, tlorth

bound leg along. railroad employed A-C and B-D LOP waypoints to Snow Hill. VOR and Sal.sburya Flight route was Wallops.

.

173..

^ ^? 1 ^; 4', ^f ^t ' it Flight No, 1-21 (Con t) ^.) , direct New Church railroad bend (.Wpt SUI^^MARY: n direct Kellam railroad bend (Wpt 2) reset with AC/BD LOPs,direct New Church (Wpt 3), direct Snow Hill VOR (Wpt 4), direct Salisbury (Wpt 5)0 i _ _: n Land Salisbury ^' S 5 Wpt 5 ^ 4 4 Powerline station 3 AZe5113; 2 Wp t 4 New Church rr 0 0 Parksley 1 5 1656 15 Onancock hwy :bend Melfa apt Exmore • 12 i2 AZ 4 .^^ Reset using AC/BD >> 1646 Wpt 2 10 - 10 Exmore Melfa apt 8 Onancock hwy bend ^ Parksley 5 5 Bloxom 4 Hallwood Altrn mod. to heavy rain 1623..

AZ 2 new LOPS EDT 3 COM/NAV off, heavy rain ` ^ Wp t ^.

` ^ 2 2 a Using AB/BD LOPS _ L--^ t ^ 1 1 '1/0 Wallops, light :.an 75 50 25 Otf ar w Right Lefl • MTG .Flags Needle Deflection.

Figure A.5-1 Flight 1-21. Miles to G^ and Needle Deflection i i 2 ^,--- ,• -;:^ ^^^ ^.:..,..,,..,.

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S/^1 .Station A (dB) S/N St^.tion B (dB)

Figures A, 5-^ Fligk^t 1-21 S/N Stations A and B

17:6 ^^ i I w-' i.

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r 3 3 1710 2 1 1 0 0 1656 15 1656 14 14 13 13 iz 12 1646 11 1646. 11 9 g 8 8 1636 ^ ^ 7 ^ 5 5 4 4 .1623 .EDT EpT ^ 3 i ^ i 1 1 t ^ 10 0 -10 -20 -30 10 0 -10 -20 -30 S/N Station C (dB) S/N Station D (dB) Figure A,5-3 Flight 1-21 S/N Stations C and D 17^ j;^; '.

^'s ^ 1 ^ ^ 1 TEST DESCRIPTION Flight Noa 1-22 TEST OBJECTIVES: Obtain position accuxacy checks ^,^ a function of LOP pair selection, test coast effects on various LOP pairs, flying along constant LOPs, DATE: 8 1Karch 1975 TIME : 1000 - 1256 EDT ORIGIN: Salisbury DESTINATION Salisbury Constant LOl?s from Snow Hill VOR ROUTE: ALTITUDE: 2000 fto WEATHER: VFR, 6000 ft broken ceiling moderate turbulence SUMNSARY: Flew along constant AD LOP (+ 1 AB lane)., (legs 1 and 2), constant AC LOP (legs 3 and 4), .constant AB LOP (+ 1 AD lane) (legs 5 and 6), constant BD LOP . (legs 7 .and 8), constant BC LOP (legs 9 and 10}, Climbed to 7200 ft to determine cloud top.

Boderate turbulence along route of flight„ i ^ f '.

Tape change 15 1/2 W outer coast CN=600 14 Start turn 13 Outer coast W-L-W ^- 12 1125 12 Inner coast 1;-W _ ^il 1/$ S SWL VOl^ • 10 i0 1/4 S Pocomoke g $ WSW Pocomoke: ` AB=AC=O,' CN=2G^0 WSW Pocomoke a 1115 7 Rte 13, 3 S Pocomoke 6 Begin leg S AB=O, AC=1 then CN=600 5 5 Coast W-L, J.-1/2 SW Gr.nbk 4 Coast W-L, l E Ilgrntown Tape change _ 2 S Rte 175 at Chinctge _ 2 1/4 S WAL CG, CN=400 - 1 1 1 N[d WAL CG, Wsl A • 0 Shelly Bay, Wsl A Coast L-W, 2 SW Grnbk SWL VOR, begin leg 4 • 14 14 Pocomoke River = 13 CN=800, fly SSE 12 Wpt AC north: Omega • ^ 11 3 NW SWL, CDI jum4^ad rt 1 i -Q 10 Reset SWL, AB/AC, leg 3 3 SSW SWL VOR, coast effect t q rt ^ 9 1035 9 1 E WAL my 10-2$ coast E $ g effect to 3t 1 SE WAL t ( Tape change, CN-400 5 }. -^ 5 Reset SWL AB/AD le 2 SWL: dmega, ^/T ^ 4 Wpt WAL 3 Powerline 1021 - ^ EDT Wsl A, heavy turbulence ^ 2 Flq const AD, CN=800 SSE ^_^ SBY, fl W again, 2000 ft ` ^ Return SBY to reset __^ Fly W const AB < < i ^ 1 1 T/0 SBY, AB/AD 75 50 25 0 tf ar w Right Left MTG Flags Needle Deflection Flight 1-22 (Part 1) Miles to Go and Needle Deflection Figure A.6-1 ^ ^_ - _ _^ . _ .... .

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Flight Z-22 (Part 1)

Figure A.6-Z 1^0 1135 -^ 1135 , ^ i3 13 -s^^=" 1125 12 11 11 ' 10 ^ 10 '^ 9 q 1115 1115 < 7 7 b 6 ,^^ 1105 1105 ^. 3 7.

1055 0 1055 0 14 14 ^- 13 ,12 1045 ^ it 10 ^- 10 1035 q ^ 1035.

q T 4 - `^`,.` 1021 1.021 '^"` EDT , EDT 2 2 ^^...

.^ , 10 0 -10 -20 -3C^ 10 0 -10 -20 -30 S/N Station L (dB) C (dB) S/N Station C and D S/N Stations Flight 1-22 (Part 1) Figure Aa6-3

f I ^^

land Salisbury SBY VOR ^^ }r end SBY - ii Powerline, 2 E SBY 7200 ft, 1eve1 with 1285 10 - ^ cloud tops 1 S Newark - Climbing thru 4000 ft g - - Tape change, AZ SBY g '° 1235 1 W Newport Bay coast Tate 365, • • 3 ESE Snow Hill ^ 7 b Girdletree, bends 1t :. SWL VOR. .

5 5 4 New Church, bends rt CN=4•^0 3 3 Wpt: Omega 2 2 SW New Church power line int ' i 1 New Church 0 1215 Start 1e 9 Reset ABJBC, SCdL VOR Girdletree 14 1/2 -S Rte 365 Turn W toward Snow Hill.

13 13 Tape change ^ 12 Cr1=800 CJp t : Omega , Lt turn to fly para11e1 to coast coast effect 10 1/2 CJ Girdletree, power line SOIL, start leg Q, ii55 Rte 1.3, mod turbulence 8 8 Wpt: Omega, CN=400 6 b L S Pocomoke River mouth - ^ i145 5 Powerline, 2W New Church _ EST 4 ^ 1 N New Church over Rte 13 - CDI and MTG more stable Reset AB/BD, CN=800, leg?

-- 3 1 E SWL, vJpt SWL:Omega 2 2 - ^ 1 CDI jumped lt, inner i e coast W-L 0 tf-o r w 75 50 25 Left Rig{^t Flags Needle Deflection MTG Figure A.6-4 Flight 1-22 (Part 2) Miles to Go and Need^e Deflect^Lon I L _l ^: , ^, ,` '; ^

j ' ^ 1255 ^

^.

3 , ,^ 11 1245 ^ 10 1245 ^^ ..._:^- =^^ 9 ^= 1235 '^^^ 1235 1225 ^^ 4 "^ 3 121.5 ^^ ^ ^ ' '^ 14 """- -^' 1205.

1205 ^ 12 12 r :.^^ - 11 11 . ^ 10

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^• ^

1155 —^^'_^" ^. . bse . :^.

7 7 6 6 1145 S 1145 EDT EDT ^` ^' 3 3 ^^^ 2 2 ]0 0 -]0 -20 -30 10 0 -10 -20 -30 S/PJ Station A (dB) S/P7 Station B (dB) Figure A.6-5 Flight 1-2.2 (Part 2) S/N Stations A and B 1255 1255 1 i i0 1245 1245 10 8 8 5 5 1.225 3 3 ^ 1 1215 0 15 15 1205 12 1205 1.145 5 1145 5 EDT EDT 4 4 ^•• 3 2 2 10 0 -10 -20 -30 10 0 X10 -20 -30 S/N Station C (dB) S/N Station D (dB) Figure A.6-6 Flight 1-22 (Part 2) S/N-Stations C and D ..

1 ^ , i,_ TEST DESCRIPTION

Flight rdo. 1-23

TEST OBJECTIVES: Compare Omega course numbers along Snow Hill VOP. radials to determine magnitude and direction of coast e`ects. ClZeck.

waypoint accuracy. Flight route: Leg 1, 120° out, 330° in; leg 2, 270° out, 060° in; leg 3, 060° out, 270° in; leg 4, 330° out, 120° in; leg 5, 210° out, 360° in; leg 6, G30° out, 180° inbound to the Snow Hill VOP.,

DATE : 8 r-Tar ch

19 7 5 TIME : 1556 - 1747 EDT ORIGIN: Salisbury DESTINATION: Salisbury ROUTE: VOR C"loverleaf (30° radials).

ALTITUDE : 3300 ft .

WEATHER: VFR, 6000 ft broken.,. 20 kts, NNW SUMMARY: Cloverleaf was f-lown to minimize upwind flying. Detected coast effect scallops ; __. I 1 ._,_ _ ._ i t Flight No. 1-23 (Con't) half mile in magnitude. No local inter- SUi^'^'I^RY' Terence near Snow Hill VOP.. P.eturned w^.thin one mile of ^aa^point each time , ^, _ TEST DESCRIPTION Flight No. 1-24 TEST OBJECTIVES.: Obtain S/N data on non cardinal di from Snow Hill VOR, test coast eff determine C-D LOP direction and. si Flight route: leg 1, 135° outboun in; leg Z, 285° outbound, 075° in; 075° out, 285° in; leg 4, 345° out in leg 5, 225° out, 015° in; leg out, 1.95° inbound to the Snow Hill DATE: 9 March 1975 TIME : 0956 - 1245 EDT ORIGIII: Salisbury DESTINATION: Salisbury ROUTE: VOR cloverleaf (30° radials) AL?'IT11DE: 3500 ft.

WEATHER: VFP., 15 kts, NG1 SUMMARY: Cloverleaf repeat of Flight. 1-23 (ofd by 15`') . Flew constant ^.",--D LOP east bound over coast., on west. bound leg encountered deviation indication to ^ ^ ^ , Flight 1-24 (Con'L-) SLTF^lARY; which was uncorrectable by maneuvering the aircraft. Reset over .Snow Hilt VOR using A-B and B-D LOPS to begin I^.S approach to Salisburyp l.$f3 _ 3 ^^ .. ^ i ., 1 1 ^ ^ ^ ! t i, !, '^ r' TEST DESCPaIPTION Flight No, 2-1 TEST OBJECTIVES: Initial check of Omega reciev^r operation, acc^xracy compared to visu^'_ and VOR references, DATE: 22 T^ovember 197,• T INdE 1430 - 1605 EST ORIGIN: Bedford DESTIIVATIOP^: Bedford ROUTE: Bedford - Lawrence VOR. ^• Bedford ALTITUDE: 2400 ft.

WEATHER: VFR, 10 kts E, gusting to 20 kts SUMMAR`I : Initial flight . indicated the necessity for hard mounting the reciever, indicator and antenna coupler to provides the required chassis ground to receive usable sgnalso Nn recorded data since flight preceded installation of CIU, , ^ _ _.

l TEST DESCRIPTION Flight No. 2-2 TEST OBJECTIVES: Provide initial information concerning the operation of the test equipment along the Northeast Corridor, P.oute of flight is: Bedford direct Framingham, (^Jpt 1), direct [^^oodstock, Conn. (Wpt 2), direct Central, Conn. (Wpt 3, 7 SW Middletown Condo), direct Hudson River at Ossining (Wpt 4), along Hudson past East River (Wpt 5), Empire State Building (Wpt 6), Statue of Liberty (Wpt 7), direct Jones Beach (Wpt SA), direct Jamaica Inlet (G?pt 9A), direct Farmingdale airport (Wpt l0A).

DATE: 23 November 1974 TIME 0950 - 1145 EST ORIGIN Bedford DESTINATION: Farmingdale ROUTE: Zulu-2 with divert to Farmingdale ALTITUDE: 2000 ft, 5"0 ft through New York TCA WEATHER: VFR, 15 kts, SW 191.

-...

..

^ Fliglit No. 2-Z (Con't) SUMNTA.E'.Y Some waypoints along the Hudson River were incorrectly computed, but otherwise half mile accuracies were consistenr_Zy achieved. Only recorded data was strip chart recording of CDI presentation.

jj i 1 ^. 7 TEST DESCRIPTION Flight No, 2-3 TEST OBJECTIVES: Initial flight employing interface ha:d- ware Check point to point accuracy, determine S/N levels and interference during Station A transition periods DATE: 3 December 1974 TIME : 1231 - 14^^2 EST Farmingdale ORIGIN: Bedford DESTINATION: Farmingdale-Mattituck, ^Iattituck-Bedford ROUTE: ALTITUDE: 2000 ft WEATHER: VFR in haze, 10 kts W SUMMARY: Weak signals precluded successful navigationa Station A phase lock was lost several times on both legs of flight...

Flight continued through local sunset, although data tape was stoppedo ^.

.

. ; ^ 1 1 .^ t TEST DESCRIPTION Fliglic No e 2-Z1-7, TEST OBJECTTV^ES: Provide additional low altitude data in the Northeast Corridor and check CIiJ operation after modification to mate the CIU with the Wango Measure mangitude of diurnal effect Proposed Zulu-1 route was: Farmingdale direct tower 376 (Wpt 8), direct Stacks on Long Island north shore (Wpt 9), direct Griswold (Wpt 10), direct South Foster (Wpt 11), direct Millis (Wpt 12), direct Bedford (Wpt 13), DATE.: 20 December TI1KE: 1530 - 1700 EST ORIGIN: Farmingdale Bedford DESTINATION: ROUTE: Zulu-1 from Farmingdale ALTITUDE: 5500 ft.

WEATHER: VFR, 18 kts X^1W Flight No. 2-Z1-1 (Con's) SUMMARY: Waypoints set in with +BD LOP changes were inaccurate due to .failed sign. chip on LOP 2. Accuracy was within one mile with -BD LOP Waypoints. Some coast effect was noted near Griswold Airport. Actual flight route was.: Farmingdale t^ a position southwest of Bridgeport (Wpt 9), direct Griswold (Wpt 10), then. as planned.

^^ s e^ ^! ^ ^^ ^t r (I Vp`• F^ ^,!

.^ 3 !^' .

¢I F^ ^f TEST DESCRIPTION Flight No. 2-^1-2 TEST OBJECTIVES: Shakedown flight after repairs to reciever, indicator and interface unit Collect additional low altitude data.

First flig^,t with receiver and inc',icator

hard mountea and antenna cable repaired.

DATE: 24 January 1975

'TIME: 1556 - 1720 EST

ORIGIN: Farmingdale DESTINATION: Bedford ROUTE: Zulu-1 from Farmingdale ALTITUDE; 3500 ft.

WEATHER: VFR in haze, 20 kts G^]SW

SLTMNIARY: Receiver functioned .satisfactorily after

radios turned off. Encountered. difficulty with +BD LOP waypoints due to previously undetected failed chip. Flown at middle altitude to test diurnal and coast effects higher than proposed VTOL routes.

TEST DESCRIPTION Flight No. 2-4 TEST OBJECTIVES:. Short range night accuracy check:. and S/N observations to determine necessity for alternate mounting of receiver as well as general navigational. capability ckeck.

DATE.: 27 January 1975 TIME: 1733 - 1825 EST ORIGIN: Bedford DESTINATION:.. Bedford ROUTE: Bedford, Fitchburg, Worcester, Marlboro, Bedford ALTITUDE: 3000 ft, WiEATHER: night VFR, 20 kts, WSW SUMMARY: LOP 2 sign chip failure detected over Fitchburg, Accurate waypoints on return to Bedford., using opposite sign input on LOP 2.

^> t: ^ TEST DESCRIPTION ii {` Flight No. 2-5 ^!i ij fi TEST OBJE^:TIVES: Accuracy check of waypoints with alternate E LOP sign input.

Leave receiver at Farmingdale for repair.

DATE: 30 January 19?5 TIME: 1533 - 1703 EST ^^ ORIGIN: Bedford ^' DESTINATION: Farmingdale ROUTE: Bedford, Marlboro, Windham, Flying B, Farmingdale hZTITUDE : 2500 f L ^ WEATHER: VFR, 15 kts, W SUMMARY: Omega receiver functioned normally on flight to Farmingdale and supplied acceFt- albe navigation information on the flighto Omega waypoints were within one half mile of visual waypointso Second half of flight data losto Noticed coast effect on both sides of Zong Island Sound.

',{ S' 1.9 8 ^,: ,, ^, TEST DESCRIPTION F7..ght No 2-6 TEST OBJECTIVES: Single waypoint long distance flight to fully employ Omega RNAV capability. Deter- mine extent of coast effect at higher altitudeso Check interference at altitude and with radios off DATE: 31 January 1975 TIME 1834 - 2004 EST ORIGIN: rarmingdale DESTINATION: Bedford ROUTE: Farmingdale- Bedford direct ALTITUDE: 5500 fto WEATHER: Night VFR, calm SUNIIKARY: After radios were turned off, receiver indications became very stable. Little observable coast effect at altitude.

ar-.dicated waypoint was one mile short of actual, possibly due to flying during D.

transition period for Station _ i 1 __ _ _ Connecticut River -4 ^^^ 3 E New Haven apt, coast W-L Middle Long Island Sound 18: Small peninsula (Crane Neck Point) Coast L-W {- 3 EST COM/NAV o£f 2 1 N Farmingdale.

I

k°

^ ^ ^ 1 T/0 Farmingdale.

l , 75 50 25 0 tf a ^ w •Right Left- MTG Flags Needle Deflection Figure 13.1-1 .Flight 2-6 (Part 1) Miles to Go and Needle Deflection 2.00.

^_ ^_._.__-_::I ^1 ^ } ^ ^+ 1914 ^ 1914 ,^ ^, IX' G ^; .

r ^, ;, .^ ^^ 4 ^' ^ 1904- . 1904 ^' ^ !

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10 0' -10 —20 —30 10 0 -10 —20 —30 ^' ` (dB) S/N Station B S/N Station A !^dB) ^ (Pant 1) S/N Stations A and

Flight 2- 6

^' ^ Figure_ga1_2 Zo _ r :^ I 'Y; ^ e^.- 1914

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^^ ^ ^ h •y w ,f ;, 10 0 -10 -20 -30 10 0 —10 -20 -30 S/N Station C (dB) S/N Staton.D (dB) ^; z Figure B,1-3 Flight 2 -6 (Part 1) S/N Stations C and D ^a .

.^ z..

^• w f ^ ^ 2 SW Bedford 11 COM/NAVl on 10 COM/NAV2 •on 10 9 COM/NAV1 off 8 COM/NAVl on 7 Descent from 5500 ft 1937— 6 2 W Windham apt Strong A, B, D, Weak C EST ^."Z^i.,,,., 9 .^ _ 19: r----- -^ ., i ^ ;^ r ^f TEST DESCRIPTION Flight No. 2-7 TEST OBJECTIVES: Obtain S/N data at low altitude near: te7_evision transmitters, urban areas, over: ` powerlines, and during maneuvers.

Deter- mine ability to maintain holding pattern and fly approach, in the shadow of Mt,

t^'achusetto Fly at low altitude (200 ft)

perpendicular and paralle " to bigh volt- age transmission lines, DATE: 7 February 195 TIME: 1617 - 1811 EST ORIGIN Bedford DESTINATION: Bedford ROUTE: Bedford, towers, Framingham, Gardner_, Haystack, powerline, Bedford ALTITUDE: 1000 ft, 200 ft over powerlines WESTHER: Night SVFR in scattered snow showers, 5 kts, NW SUMMARY: Flew to avoid snow showers, completed two and a half orbits around Norwood q ^ 206 '1 k tea... ___. _. _ .. ... __ _.. ". _._ _..._..

a f 1 r ^.

Flight No. 2-7 (Con't) SUMMARY: television towers at 2000 ft, 1500 ft, and 1000 ft MSL, with no effect on indicators or increase in weak signal lights. This was also true of flight over Framingham, within 200 ft of power- lines and during maneuvers (stalls, spirals and steep backed turns over klaystack) o Ail RNAV approach =aas made to Cazdner Airport with. waypont indication 1/4 mile south of the actual airporto holding patterns were difficult to fly due to moderate noise in the Station A signal. Recorded data was last in soft- ware transfer o TEST DESCRIPTION Flight N^o 2-8 TEST OBJECTIVES: Fly low altitude Zulu routes from Bedford to College Park and retain employing all four Zulu routes.

DATE: l0 February 1975 TIr'IE : 1009 - 12.15 EST O RIGIN: Bedford DESTINAlTON Flushing ROUTE: Zulu-2 to Statue, divert Flushing ALTITUDE: 2000 ft, 1100 through New ^:ork TCA ?^^ATHER: `'r R, slight haze 20 kts, W, SUNIIKARY: Flight proceeded as planned until passinb the Statue of Liberty tishen Station D ^.

(North Dakota) ceased transmitting.

return to Flushing Airport was made by pilotage.Second half of data lost.

during software transfer..

i , ^i '^ ;^ TEST DESCRIPTION ' ^^;;^ Flight No. 2-9 ^` %^ TEST OBJEOTIVES: Test alternate LOP pairs AB and BC. Fly ^ ' alternate Zulu route to Bedofrd from Flushing after Station.D stopped trans- .

^' mitering.

,^a DATE: 10 February 1975 f ` TIME: 1300 - 1450 EST ORIGIN: Flushing r DESTINATION: Bedford • '' ROUTE: Flushing, Bridgeport, Windham, Bedford ALTITUDE: 2000 ft.

WEATHER: VFR, 20 kts, W [ ^^ SLTIrII^1ARY: Experienced difficulty obtaining synchxo- h nization at Flushing. Reset using AB and '; • BD LOPs as Station 'D had returned women- tarily. Lost track over tower 376 way- ^.` point when. Station D stopped transmit+ping j again. Reset. over Bridgeport using AB and {; ^ BC LOPS, and returned to Bedford. success- ^' Y fully. Recorded data was lost during ,; ' transfer through software.

r __ f ' f 5k .I ^.

i <, ' '4__ .._ __ _ _ 1__ ., ^ TEST DESCRIPTION Flight Noo 2-10 TEST OBJECTIVES:. Fly low altitude Zulu routes from Bedford to College Park, Maryland using Station pairs A-B and B-C. The Zulu-W route begins at the Statue of. Liberty (^^^pt 7) , direct Verrazano Bridge (Wpt 8), direct Jersey rail yard (Wpt 9), direct Dublin (Wpt 10), direct powerline and river (Wpt 11), direct Dayton (Wpt 12), direct College Park (Wpt 13)0 DATE: 14 February 1975 TIME.: 1034 — 1413 EST

ORIGIN; Bedford

DESTINATION: College Park, Maryland ROUTE: Z2 and ZW ALTITUDE: 2000 ft., 1100 ft through New York TCA WEATHER: VFR, 10 kts, SW gusting to 25 kts SUMMARY;. ..Skipped waypoint 7 due to traffic in the area, As the flight proceeded, the way- point indications were increasingly early r.

K Flight No, 2-10 (Con`t) due to possible calculation error or weak Station A S/IJ, Approaching the Susquehanna River .it was determined that the A-B LOP had shifted by 2 lanes and compensation. was made.. The final waypoint indication was 2 miles late with. the altered LOP. inputs,

I

TEST DESCRIPTION Flight Noo 2-11 TEST OBJECTIVES: Provide S/N data during. precipitation, .

Investigation of terrain effect of south- ern Catskills. and Berkshires. Provide initial information on use of system during IFR conditonso DATE: 17 February 1975 TIME: 1621 - 1931 EST ORIGIN: Dulles Airport, Washington, D^ Co DESTINATION: Bedford ROUTE: Dulles, Martinsburg VOR, Lancaster, Lake.

Henry VOR, Pawling VOR, Bedford ALTITUDE: 7000 fto WEATHER: IFR in varying light to heavy rain, .light icing conditions SUMMARY:. Takeoff at Dulles Airport in light rain Wayponts were with one mile visibility.

chosen along the expected . IFR clearance route wherever VORs coincided with ^: i Flight No, 2-11 (Con't) SUMMARY: airports due to lack of precomputed IFR waypoints, Weak Station A S/N caused track loss. Receiver was reset over Honesdale Airport and again 6 miles south of Monticello Airport. This same offset bias was shown when landing at Bedford.

Light and heavy rain encountered enroute had no .observable effect on S /rao Flight was conducted at high enough altitude as not to show terrain effectso Reset location inaccuracies precluded measuring any small diurnal effect presento — a ^ <.

Tape change ' 15 .; 1721 Showmaker Int, rescale MTG x Ws 1 A ^ _- 14

14 Veryy heavy rain

-i3 _....^.^^•`^''"'

^•13 AZ LRP (Omega-From)

•::^„^ Heavy rain, along V93

Wsl A -^,,, Z" .1711 Wpt LRP: Omega and VOR - Y.., Light to heavy rain ^^ - -_ 11 Delroy Int, 18 WSW LRP .:Z Q - „} •; 1701 Hanover Int ' ^: 10

Heavy rain

.-^ ^, Wsl A Ws1LAP, - ^ $ . "M' 8 Tape change ^ ^ - ^ 7 j' 7 Harney Int V39, Wsl A ;, ^ ^r AZ LRP, hdg 085° - _^ 6 5 Ws1 A "' ' S ._.:' _ ^•~ '^ Wsl A ° -- ^`^ 1641 ,...

• ^• Wsl A consistent

Y '^•^, = ^..._^ Q "'^ 4 Heavy rain '^-^:^ 7000 £t, OAT=3°F 3 _ e Wsl A consistent ^^`^ ..

e Climbing to 7000 ft ,^' Heavy rain a., EST 2 - s `-1, - —`^' Wsl A consistent ^'•^ g 1500 ft, vectored- W of IQD • ' Wsl A consi^ tent ,i _ 1 - 1 T/0 IAD, light rain.

tJ.,..L.^,:- 75 50 25 0 tf or w .Right Left MTG Flags Needle Deflection ' B.2-1 Figure Fight 2-11 (Part 1) Miles to Go and Needle Deflection ._ r...

.1721 -: ' ^ — '+ 15 1721 - --.

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--^ EST _ .

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...^ _ -_ _ i0 0 -10^ -20 -30 10 0 -10 -20 - -30 S / N Station B (dB) S/N Station A (dB) Flight 2-11 (Part l) S/N Stations A and 8 Figure B.2-2 ti f ^' .^ 1721.:.

^ 1721 • - 15 ^::,^. ^^, ^, - 13 •'^•,, l3 ,.

^^ ^ ^^ '=:-^- 1711 y^ ^ v+ N.

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^ ^ `^^ 11 "" 11 P .^p^ .,^ S ^' 1701..

r' ^^+ ' -^,- 10 :... 10 ^ ..^ ^; 8 -,- f..

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^.^ ^ ---^.^ ^ ' :::_ .., 1631 • ^ •3 . w^;- EST ^ fST 2 . i .G" ,l a^`^ --,.y ^ . ., ,^. .

10 0 -i0 -20 -30 w 10 0 -10 -20 -30 SJN Station C (dB) S/N Station D (dB) Figure B^2-3 Flight 2-11 (Part l) S/N Stations C and_n r

216-

i' ^, ;^ _ ,.._ ^ i ,_ ,_ _.. ,_ _:_^.^ , ,.. ^ ., _ J.

.^ i• •L.

Tape change Clear of clouds :---,,, - 15 15 Adj MTG, AZ Bedford ^;^ 1818 14 Walden Int, adj MTG and CN 14 _., to center CDI ,a r __ ^ 13 1808 13 Monticello, reset ^„_^,.. 12 Set in Wpt BED from Monticello ' Change CN by 400 - 11 . AZ Honesdale ;' 11 -••*^-' • 10 Tape start 1758 Tape stop 1757 f- _ 8 ---^---^^,,, Reset Honesdale, 1755 e'erf Tape start 1754, 6 E LHY `" 7 `•"'^ Tape stop 1751, light rain ^•• 6 Wsl A, B, D, lost. phase lock =' t!°^1745- Wsl A, B, D 4, ^ . Mod rain between layers ^ 5 5 •••^ = Wsl A, B Wsl A A Wsl ' ^ C__ Ws1 A s•' ;^• Wsl A, B Z rf.

^ Very'heavy rain, Ws1 A "'^ a ^i ,,,__,_,^: ^ 1735 4 4 Adj CN to center CDI ^ ` " `.'y'? E5T 3 Very heavy rain ^^^ 2 1 N Snyders Int

2 ^

TAS ^, =13Z MPH, W.^l A _ ^ ^`''-, Changed SENS adj down and up 1 VOR=2°R, Wsl A ^ l ^ r 0 ''' 0 Time mark (1725.:30) 75 50 25 0 Right tfar.w Left MTG Flags Needle Deflection , Y Figure B.2-4 Flight 2-11 (Part. 2) Miles to Go and Needle Deflection _r 1828 ^^ . •^ ..^.

,,,,^ ^,.r °. F ^ ^:, •--' ,..

':.

,,^ ^`^ 18 T8 1818 ^ ;;^ y,* ^,^,^`^' .^ ^-14 14 ,^: M^ `^ , ^'^ 1808 - 1808 `^^ ^..^... •^ 12 •^ ,, ... , K ^,,,,,, *, •_.

^ ^ "^-- 11 ^,:; ._. ^...- ., .

.^y.4 8 _ 7^ ,• ,, 7 ,,.

1745 ^„ ^_.. 1745 ^. ...

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10 0 -10 -20 -30 10 0 -10 -20 -30 S/N Station E (dB) S/TJ Station A (dB) A and B S/N Stations 2-11 - (Part 2) Figure B.2 -5 Flight 21£3 .

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EST ^.^.; EST `"-`' - ; ,i 10 0 -10 -20 -30 10 0 -10 -20 '-30 S/N Station D {dB) S/N Station C (dB) Flight 2-11 (Part 2) S/N Stations C and D Figure, B.2-6

219-

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J, " — ' may 14 Land Bedford

ti 13 Bedford MM _ ^^ BED OM, Asl A :" AZ BED

0 12 II -' 12 Abeam Minuteman apt

11 Rte I495 1922 ^ 10 „> 10 Radar fix 8 W BED OM Cloud bottoms 2400 ft ^„^

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9 Aligned BED ILS Start descent 3 ' 8 Adj CN=200 for BED ILS

1 l

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r ^ ^- i r .Ws1 A ._----^ - Time mark (1902;30) 1902 ^ Leading edge icing fi r 6 Rain

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12 W RNZ 4 Holbrook Int Y Cloud bottoms '^ Clear of clouds ^^, 3 Slight rain,. in and. out of ^' 184} - clouds EST

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^' - 2 Strong A, B, C, D, clear of ^^ clouds and xain 1 a ^ 1 PWL ^^OR ^ ^ L.1 ..

75 50 25 Otf a r w Right left

MTG Flags Needle Deflection Figure B.2-7 Flight 2-11 (Part 3) Miles to Go and Needle Deflection ' ! I ^ 1932 .,>.., .^ tea. z^,...^ .. -13 - ^^..

rt -^°-- „ • a , .11 .:,^-^'"'"-^ .11 ~-"' "` . 1922 •,^,:,;-• 1922-- ^.

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^ 1912 i912 g ^ ^^ 8 ^ r* 5' ,,.^„ .

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jr 1841 3 '"^, 1841 •^ ^• ^ EST EST ^^ '^^ ^ 2 -^.. *-• r' 1 r.S 1 0 -10 -20 -30 -10 -20 -30 10 10 0 Station B (dB) S/N A (dB) S/N Station S/N Stations A and B (Part 3) Flight 2-11 Figure B.2-F3 ^^, .1932 3 1932 ^,_,, 14 7^ ... 14 ' 13 _ ' ^`^'^'^^ 13 :.^n.s..

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1.922 `^^. ^ ^ ^; 192?. ^^ ^ 10 I ^, t,^' ^ ^_ .c:;_^^,,,^ ^^•-yam ^,.,.^; , ^ r ^""' -' 1912 ^ 1912r r yu O C'• ^^ L^ ^• ^.

^^ `^ i^ ^;^ „c •, , .^ ^' .

rt :.= . t... 5 5 ;^^ ^ •^ ^^ ^' ,^y ..._ 4 ^' '^ 3 R^ 1841-^ «^ 1841 ••'' 3 ".,`r EST EST ^; 4^ ;^. ^ ;, _.: °- .^ ^ f^ i ^ 10 0 -10 -20 -30 10 0 -10 -20 -30 S/N Station D (dB) S/N Station C (dB) Flight 2-11 {Part 3) S/Id Stations C and D Figure B.2-9 TEST OBJECTIVES: k Obtain additional S/N data along Zulu routes before diverting to Salisbury, The Zulu-S route begins at the Statue (Wpt 7), direct Verrazano Bridge (Wpt S), Preston Airport (Wpt 9), Bordentown (Wpt 10), Camden (Wpt 11), Salem (Wpt 12), then direct to Vienna Y^Iaryland (Wp t 13), Salisbury (Wpt 14)0 DATE: 19 February 1975 1210. - 1530 EST TIME: ORIGIN: Bedford DESTINATION: Salisbury

ROUTE: Zulu-2, Zk;^:^.^1-S, divert Salisbury

ALTITUDE: 2000 fte , 1100 ft through tdew Yorl: TCA

WEATHER: VFR, 15 kts, SW SUMMARY: Flight proceeded as planned, with radios off for the majority of the flight, Skipped waypoints 5 and 6 as tiZey are very close and almost colinear with 405 and 7.

-^ __.._...n l . _ Tape change ^.

1308 ^ 1 N Rte 15, abeam watchtower _- AZ4 12 ^ Wpt 3: Omega and visual _ 1 W tower 525, Conn. River - 11 1258 11 ^r 1 NW Marlborough 10 ^ - 9 1-1/2 WNW Columbia q Clouds bank at 2000 ft 1248 ^.

2-1/2 NW Windham apt ^ Wpt 2: Omega • .j 2 NE East£ord r g " ' _- 8 Tape change • 124p ^, J 1 SE Webster i b S tip Manchaug Pond '' b ^^ 1230 1-1/2 S course Powerline, 4 W 1495 - 5 .Rte 1495 - 2 3 ^ 3 ^^ ;" •^ 1220 •.

Wp t 1 ^ 2 ^ EST •• 2 COM/NAV off ..

Wsl A, snow cover ire NEC n T/O Bedford 1 Time mark (1210:.30) i ^ ^ ^ 1 h1...1....l.

Right 75 50 25 0'tf a r w Left MTG Flags Needle Deflection Figure B„9-1 Flight 2-12 (Part 1) Miles to Go and Needle Deflection . :.- • =^^ ^..

.:^'^ '^ - ^..` 1308 ^" ^:.^ 4 r.1-.. y.

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1 I.. r p ' -^ ,.....,.., ^ ry ^ ^ ' 1 J _T' 1 L^,L— ^ , ^ . 10 0 -10 -20 -30 10 0 -10 -20 -30 SAN Station B {dB) S/N Station A {dB) 2-12 (Part 1) 5/N Stations A and B Figure B^3-2 - Flight Y ^,_ ., r.,s ^ • '^=• 1308°^ ^ :^,-^.. j,.

^ 1 12 ^„^^ ^ : ^ ^ 125. 11 y ^. ^ ^ ,:; ,.

^'' 1248 ^ s} 1248 -- .._„ ; rF ^- ^ {{{ ^ »+ ^ 8 g 1 1240 ^ ,r ^J 1210 •' 1 ^V ^.^ :^fw O r~ ^ L ,'• 6 `+^ 1230 f^ 1230 ^- ^..

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r..:,^ 1 2 0• ^^ 1220...

=-......,,._„ ,.E^T 2 ^ EST ^;, 10 0 -10 -20 -30 10 0 -10 =20 -30 .

° S/N Station n (dB) S/N Station C (dB) , 1{ t 'i Flight 2-12 (Part. 1) S/N Stations G and D ^; Figure B•3-3 ,., y

^_ ^

Y' Tape change ^" 4 E Hightstown, 2 E course _ ^ . = s5 = Ws1 A - ^' - ► - j 8 Wpt 9: Omega and visual.

Hazlet highway, 1 W course - ^ 1401- Climb to 2000 f t Crookes Point, 1 NW course 7 Wpt 8: Omega and visual r a 7 —^""`^== ^^ - 1351• 6 Wpt 7: Omega and visual World Trade Center, Ws1 A Empire State Building.

a ' S G. Washington Bridge _ 7 AZ 4 ..^..^..^-^^ ..,.^ 4 Time mark (1344:40) Tape change _ _ _1343.

^'• -. 1 N Wpt 4.5, Wpt 4.5: Omega 3 Sparkill Peninsula, Wsl A _ - —^...e^^ ;X ^,,,,, Tappanzee Bridge Wpt 4, 1100 ft ,' Adjust LOPs Wpt 4: Omega, 1 E prison ^ 2 COMJNAV off, Wsl A _ 1 1 COM/NAV on, Ws1 A r 3 C CMK VOR, Wsl A NE Georgetown 0 3 ^ ^ EST3 ^^ , ^ 15 ^'s' 15 Hoosatonic River i ! 1,,,.,1 t ' ' ^ 14 i t r ^ ,^. ^ y 14 Time mark (1313:20) 75 50 25 l# r a r w Right Left MTG Flags Needle Deflection Figure B.3-4 Flight 2-12 (Part 2) Miles to Go and Needle Deflection i• 2 2.7 1 __ ' •?^ ^:%^• "' ^ 111 ^^ 1411 _. ^ •^ $ ,.

8 . ^, r^v ^^r> : 1401 ^.,. ;,^ =•^^ ^ 41 ^N1^.

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' r 'rf ""'_ '; ^^ 1333 ''.. :' "" ^- '^^w ^ ^+iDa'w . .

.M 1323 ^ d.^.

^ST3^ ^ _ r.., .,- EST ^ ^° ,^ ^ .

. =`-^-- t .15 10 0 -10 -20 -30 10 0 -10 -20 -30 `^ S/N Station A dB) S/N Station B (dB) A and B 2-12 {Part 2) S/N Stations h Figure B.3-5 Flight ; , a a 2.2 8 F . ^ r ^ • _ ,.

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-10 —20 —30 —10 -20 —30 10 0 10 0 S/N Station C (dB) S/r1 StatiOn D (dB) Figure Boa-6 Flight 2-12 (Part 2) S/N Stations C-and D • 4 Tape stop.

Land Salisbury ;.

,,, 3 1 S SBY, Wpt 14: Omega r 2 "' 2 2 N .SBY , ' n ^^ Delmar, Ws1 A ^^ Ws1 A, B ^ COM/NAV on, Wsl A ^ 1 Tape change, AZ SBY t 2 E Federalsburg r 4 NW Bridgeville 7 E Denton ..> 3 W Harrington 1505• Jenkins apt ^•, ;" 2 E Smyrna apt.

1455 - 1 5 4 N Woodland Beach _ 14 14 2 W Canton, Powerline,,3000 . -=.-- ^ ^ 13 Wpt 12: Omega, 3000 ft ft ^ _ - 12 1445 12 Time mark (1446:10) 1^ ^ ^ Tape change '^. 1 S Woodstown VOR ' _ 11 Wpt 11 11 -^^ ^ 3 NW Aeroha^en apt - f 1 NW Burlington apt, Wsl A .f 1 SW tower 247 ' ^- ' 1425 'EST Ws1 A w -: —^^... ..10 Wp t 10 Wpt 10: Omega ^ ^ ^ 1 ^ - 9L:_, .' ^ 3 ^_ 9 1 S Robbinsvilla i • .

75 50 25 0 tf a r w Right Left 'MTG Flags Needle Deflection Figure. B.3 7 Flight 2-12 (Part 3) Miles to Go and Needle Deflection _ ^'^ # _a, - .__ _ - _ _ _ I, ._. ^ , „^ _,_ r _ ^^ 1535- 1535 >....,.._ _ _ ..- ^— .._..

^^ ^' ` ....

-'..:^:.:^ 1525 T '^ F-,, ^..,+=Y w^ ,^w2^ -^9c^- ,._.

Q `^ ^ , 1515 =`^ ;^,r.,. _.

.: ..'^ w,^ — w'• 1505.- ^ .

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^ 1455 • ,^ 1455..

",- ^ 15' _ 1445 • 2 ^ 1445 , , _._ ., ♦ 1•.71^iw ^ ^ " - i'^ ^• ;,,'"' 1435. ° ^'" ,^^ ^ ....^ 11 11 - -^' ^ ^ r^ ,r,^^ r ^ f^^a^ 1425- 1425 -„ . , .. -^'' EST - EST --; - "" ^;^ .^7 Z„ -,-^- s _ 10 IU -10 -20 -30 10 0 - 10 0 -10 -20 -30 - S/N Station B (dB) S/N Station A (dB) ^ 2-12 (Part. 3) S/N Stations A and B Flight Figure B^3-8 ,, F T, .

'^ 231..

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r 4 :1, ^ x • e :...— __,^_..^.....r^--^^^^, "^ 1535 .

^, 1535 , ,,.

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• ^,. 1505 X , "' '^ •^ ^,;.

'ti • • •` 1455 •- 1455 •• ..15' - • ^- ' 14 ^' -14 '",- ' ^• ^ 12 1445 - 1445 .. -„ .; ., ^.

-=:, •r^: ='^- -^ 1435 1435 - ' .'

Ny / '7 - ► .`l 1 a^ -tip.

'""' 1425 - 1425 •^ ^.- EST EST rL; ^ ^.t^'• ^.'

10 ^ -10 ^^ a.

~ 10 0 -10 -20 -30 10 0 -10 -20 -30 S/N Station D (dB) S/i1 Station C (dB) Flight 2=12 (Part 3) S/N SL-atons C and D Figure B^3- 9 r fi of s -__ ^^ , t. ^ - ^ t - __ t TEST DESCRIPTION Flight No. 2-13 TEST OBJECTIVES: Provide S/N data and waypoint accuracy check enroute from Salisbury to Bedford via airports and along the Z-1 ^^oute,.

Flight route was Salisbury direct Wildwood (Wpt 1), direct NAFEC (Wpt 2), direct Lake- hurst (Wpt 3), direct Preston (Wpt 4), direct Jones Beach (Wpt 5), Jamaica Inlet (4Jpt 6), tower 37b (Wpt 8), then via Zulu-1 to Bedford.

DATE:. 22 February 1975 TIME: 1225 - 1608 EST ORIGIN: Salisbury

Bedford

DESTINATION: Zulu-1 ROUTE: 5500 ft, 500 ft through New York TCA ALTITUDE: WEATHER: VFR, 15 kts, SW SUP^R^IARY: Voice tape discovered inoperative over Long Islando Miles to go stopped .:e^ _ _ _ , _ Fight Noo 2-13 (Con't) decreasing over Delaware and again over SUMMARY: Connecticut (analysis showed strong S/N ratios)o Later in the flight the MTG began to increment. properly again, P,, l: ^- 5 Wpt 2: Omega and visual 5 —"—^^ r r 4 4 3 E Tuckahoe, river inlet 3 2 SE Woodbine .apt i 2 Wpt 1, Resets AZ 2 • 1 1 Cape May Point 0 0 Cape Henlopen Point 15 1 E Lewes 15 '^• 0 Tape change 1 NW Rehoboth apt 14 1 NW tower 365 13 Millsboro River _ EST {^ 12 12 ^.;( ' M/NAV off - i3r^^3, A consistent ^;'17i drift ..

MTU not counting. down • 11 Climb t^ 5500 ft L. ^ ^ ^ - 11 T/0 Salisbury ^— Left - 75 50 25 0 t fa rw Right Needle Deflection MTG Flags 1^'light 2-13 (Part 1) Miles to Go and Needle Deflection ^:' Figure B.4-1 S 4 q _ ^ 2 - 1 6 1346 0 p 15 .-15 0 0 1335 13 EST EST 12 ^ ^..

^^^°'' -^ ^.^ i e e e^ j 11 e e J e e lU 0 —10 -20 -30 10 0 -10 -20 —30 S/N Station A (dB) S/N Station B (dB) B.4-2 Figure Fli;ht 2 -13 (Part 1) S/Id SL?atons A and. B .

y ^^ ;, `; __

I

,^ ^

1406 J 1406 —i 'S 4.

^ 1 1^j 1346 0 0 '; 13 - 1335 EST ^ ^ ^ ^ i _11 t ^ ^ ^ ^ 10 0 —10 —20 —30 10 0 -10 -2U —30 S/N Station C (dB) S/N Station D (dB) ^ Figure. 8.4-3 Flight 2-13 (Part l) S/T1 SL-ations C and D m^ 2.37 , Tape change 10 S New Haven .apt ` ,.._ 8 A'L 9 Wpt 8 Climb to 2000 ft AZ 8 _ pW Mitchel apt 3 1 ` E W Expressway ` 2 2 wpt 6 ' 1445 ` 0 Wpt 5 Descend to 500 ft 15 Sandy Hook, W-L-W.

14 Coast L-W, 1N tower 561 ^^ ^13 Garden State Parkway i2 1 E COL VOR, 1500 ft ll Colts Neck apt TO rr depot, 3 NW Farmingdale S 4 W Monmouth apt 3 NW Lakewood _ AZ 5 .. 1425 7 Wpt 3: Omega and visual ^ ^ ^ ^ CYN VOR ► 75 50 25 0 t f a r w .Right Left MTG Flags Needle Deflection }; Flight 2-13 (Part 2) Miles to Go and Needle Deflection Figure B.4-4' ; ^ ^ .d ; N !

i M1 1513 1513 1503 ^ 9 1503 y 1453 ^ 1453 -^ 1 1 ' 1445 ,; •0 0 ^; 15 14 lq ;^ 11 11 ^^ 10 ;;, 7 7 10 0 -10 -^20 -30 10 0 -10 -20 -30 S/t1 Station B (dB) S/N Station A (dB) '' r^ Stations A and B (Part.. 2) S/N *^ rigure B.4-5 Flight 2-13 ^^^ 15f;,3 .

q 1503 q :?

^ 1 T445 0 0 ^ 14 i 3 K li e ',^ 9 r': 7 7 ^ 6 ^ ^ ^ ^ ^ ^ ^ i ^ 10 0 —10 -20 -30 10 0 —10 —20 —30 S/N Station C (dB) S;%N Station D (dB) ^^ and 1'i Flight 2-13 {Part ^) S/P^ Stations C Figure Ba4-6 ' FJ Y' ;.i f i fi^ - ^ n 't 2^FQ .

(• Land Bedford, tape off 3 3 S Bedford 2 Center Norwood towers 1 3 S Norwood, COM/NAV on, towers 0 Franklin 1548 ..r 15 Woonsocket Tape. change ^- 14 2 E Wp t l0 j 13 ^ 1/2 E Moosup ^_ 1534 N' MTG not changing ^' 1L 2 N tower 711, Norwich ,, r' 11 11 2 ESE Devils Hopyard^apt s;; Powerline r 1524.

EST Conn. River, 1 NE Essey -'; MTG counting up ^; ,. Light snow cover in NEC 9 g.Rte I95, 2 E Clinton.

g Conn.. coast W-L ^;: 8 ,a: `; -`^"'-L W t 9 9 P i i^^^ ^ ^^^ ^'' ^ g ^'^:_J 75 50 25 0 t f a r w Right Left MTG Flags Needle Deflection ^' to Go and. Needle Deflection .^^ Figure B.4-7 Flight 2-13 (Part 3) Miles ^( {:} .: t ., _ - w; r.^ %' '; j !i s p 'y 1524.

)524 ' EST EST r 8 g `^ ^0 0 -10 -20 -30 10 ^ -10 -20 -30 SfN Station A {dB) S/N :station B (dB)

Figure B.4-3 Flight 2-I3 (^^rt 3) ^jN Stateh°a^.^ ^4 arrr^ B

j _ r i_ 3 3 1558 - 1 15 15 1548 154Y ^- 14 ^14 13 13 1534 1.534 12 12 11 11 .1524 ^ EST EST • l0 10 9 9 8 8 ^ ^ i ^ ^ i i ^ ^ ^ 8 8 0 -10 -20 0 -10 -20 -30 10 -30 10 S/t1 :Station C (dB) S'T1 Station. D {dB) Flight 2-13 (Part 35 S/N Stations C and T Figure B.4-9 ^^ _. -- TEST DESCRIPTION Flight No, 2-21 TEST OBJECTIVES: Obtain data for Flight 2-7 for which data was lost, Test CIU output with most ' significant byte chip replaced for LOP 1 readout° DATE; 27 February 1975 1917 - 2021 EDT TIME : Bedford ORIGIN: DESTINATION: Bedford ROUTE: Bedford, television tower, I'ramingham, Gardner, haystack, Lowell, Bedford ALTITUDE: 2000 ft, Night VFR WEATHER: SUNIlKARY: Flight proceeded as planned ° Operation of radios directly . affected S/N ratios, transmissions effected data output° Replaced chip worked well on map plot, 1 ^ ^ $ ^ - TEST DESCRIPTION Flight No, 2-31 TEST OBJECTIVES: Check CIU operation with additional chip replacemento 5 March 1975.

DATE: TIME Haverhill ORIGIN: Bedford DESTINATION: Along AB LOP to BD LOP through Bedford ROUTE: ALTITUDE.: 1200 ft.

WEATHER: VFR, 15 kts SW Some difficulty was encountered with input SUMMARY: of proper initial waypoint along constant AB LOP. Reasonable navigation followed, with final waypoint indication near. the airport. reference point at Bedford.

Recorded . data was garbled..

.

..245 } ^ ..

i TEST DESCRIPTION Flight. No. 2 -41 TEST OBJECTIVES: Provide Zulu route data and preliminary S/N in the Wallops area for the second set of Wallops flightsa 7 March. 1.975 DATE:.

0926 - 1302 EDT TIME: Bedford ORIGIN: .Salisbury DESTINATION: Zulu-2, divert Salisbury RAUTE: 2000 ft, 500 ft through New York TCA, ALTITUDE:

3000 ft

VFR, 3500 ft broken cover, 15 kts, S WEATHER: Good navigation along route, final way- SUMMARY: point indication one mile south, south- west actual waypointo Recorded data ceased over Lakehurst due to failed connector at recorder. Station H (Japan) signals clearly vsibleo c F^ { TEST DESCRIPTION Flight No. 2 -44 TEST OBJECTIVES: Provide final S /N data in Wallops area.

Check Zulu route at high altitude (5500 ft to 7500 ft). Fly from Salisbury direct Jones Beach (Wpt 1), tower 376 (Wpt 8), north Long Island stacks (Wpt 9), Griswold (Wpt 10), South Foster (Wpt 11), Millis (Wpt 12), Bedford (Wpt 13).

DATE:. 9 P^Iarch 1975 TIME: 1330 - 1646 EDT ORIGIN: Salisbury DESTINATION: Bedford ROUTE: Direct beach Wpt, Zulu-1 to Bedford 5500 ft, 7500 ft over New York TCA ALTITUDE: VFR, 15 kts, NNE WEATHER; SUMMARY: Lost track ,due to weak S/N for Station A over southern flew Jersey. Tried using BC and BD LOP pair unsuccessfully. Resumed using AB and BD over stacks wpt, flying constant BD LOP Bridgeport to Bedford.

k; l ^ 1 I

•

pp Subt 2 i AB lanes AB LOP not updating 7 2 E Lakehurst, subt 3 AB ^ Level at 7500 ft Subtracted 2 AB lanes 6 COM/NAV of f 14.41 1 SW Miller apt S AB=-10.^ •5 Subtracted 1 AB lane 5 W Tuckertown Subtracted 2 AB lanes Ws1 A • Subtracted 1 AB lane 1 W Smithville apt Many Wsl' •s on A 2 2 NAFEC my 31 • 1421 Tape change 1 Transponder on, 5 S NAFEC ^ 0 2 E Tuckahoe 14?^ ^ 15 15 2 SE Woodbine ti Ground speed=109 kts •

P

^ 14 14 Wildwood apt Cape May Point, rescaled

8 MTG, MTG = 108

Cape Henlopen 11 ll 2 S Lewes Tape change r.

10 10 Millsboro, Indian River Level at 5500 ft 9 9 EDT E 8•Wsl Aa1MTGury140 Climbout after T/0 SBY ^ 75 50 25 0 tF ar w Right Left MTG Flags Needle. Deflection 1) Miles to Go and. Needle Deflection Figure B.5 - 1 Flight 2 - 44 (Part 24a

l

1 ^ _^ __

^: l^b'' `, ,: 1441 6 1441 -^• 1421.

ter • 1 1

0 0 141.2 ^'"' —s .

...

y^ 1402 1402 -'^^— }2 12 1352-^— 11 10 10 134T 1341 EDT EDT ^:'!^ 8 -,,,^ F r ^ ^ r-3i—= ^ ^.L^.J " 10 0 -10 -20 -30 10 0 -10 -20 -30 Station B (dB) ^^ S/tJ Station A (dB) S/N A and B Flight 2-44 (Part 1) S/N Stations Figure B,5-2 • j•

i

I i

7 7 1441 6 ^ 'S.^ 4 4.

3 3.

2 2 .

1 1 0 0 1412 15 1412 15 ' 14 1402 1402 13 13 1352 11 1352 1341.

EDT 9 EDT 8 8 ^ 10 0 -10 -20 -30 10 0 -10 -20 -30 S/N Station D (dB) S/N Station C (dB) - {Part 1) S/N Stations C and D

Figure Be y -3 Flight 2 44

.^ 1 Tape change - ^ 1605 0 Marlboro, Wsl A ^ .

Wsl A 15 Conno River, 1 E power plt 15 1555 ^ MTG = 80 . Wsl A Set AB=-11.5 14 8 SW Middletown 13 13 New Haven monument - '5700 ft ' No Wsl since 1518 ^ (Set AB=O) 12 12 1/2 N tower 367 Tape change 11 1 W Bridgeport,^tower 318 Z SE Owenoke 10 5 S Sheffield 1525 2 W Wpt 9, BD=+0.2 ^ Set CN=400 to fly const BD Set AB= O ' Rescale MTG AZ Wvt 9 • ^ q 9 Tower 376, reset, Wpt 8 ^ 1515 Reset AB/BD EDT BC=-Oo3 .. MTG increasing $ 8 Reset BC/BD, Wpt 1 0 t f w ' 75 50 25 c r Right Left MTG Flags Needle Deflection - Figure B.5-4 Flight 2-44 (Part 2) Miles to Go and Needle Deflection ' ^ ^ ^ ___._ _ _.

- ;.

16( 160.5 0 0 1.555 15 _ ^- - 11 9 9 ' 1.515 EDT EDT 10 0 -10 -20 -30 10 0 -10 -20 -30 8/N Station A (dB) S/N Station B (db) Figure B,5- Flight 2-44 (Part 2) S/N Statons . A and B t 252.

S 1555 15 1555 ' 12 ^ co5' ^ ^^ 5 ^10 i -^ 9 10 0 -10 -20 -30 10 0 -10 -20 -30 S/N Station ,D (dB) S/N Station C (dB) Flight 2-44 (Part 2) S/N Stations C and D ^; h Figure B^5-6 ` Tape off 10 Turn off my 29 ^ Land Bedford rnp 29

1^ ^

..

9 2 SW BED, prior to R/T 8 AB LOP not incrementing Tape change X638 ^ 7 7 PrioY^ to R/T, Marlboro apt, 3800 ft 6•Rte 1495 and Pike ..

^ ,^ 5 COM/NAV on, 2 S Westboro ^ 1-1/2 S Grafton, pow^^- 4 1628 4 Providence hwy, 1 E ne Kittville Int.

3 1/2 N Webster, rr . EDT 2 1/2 SW Lampert apt • • ^^ ^ ^ ^ 1 1 1/2 SE Storrs Right Left 75 50 25 0 tf a r w MTG Flags. Needle Deflection Flight 2-44 (Part 3) Miles to Go :and. Needle Deflection.

Figure B.5-7 ^ ^.r _ -^ ..__ ^ 1 _ _ _.

l -^-"' ----=^= 5 1628 4 1b18 EDT :EDT a, 10 0 -10 -20 -30 10 0 -10 ^20 -30 S/N Station A (dB) S/N Station. B^ (dB) ^! R Figure B,5-8 Flight 2-44 (Part 3) S/N Stations A and B s ^: ^E

i

^^ ^ ^ 1.

a EDT EDT i ;: 1 t r ^ r ^ i ., ' 10 0 -10 -20 -30 10 0 -10 -20 -30 SJN Station C (dB) S/N Station D (dB) t Figure B.5- Flight 2-44 (Part 3) S/N Station C and D ^ f' ' 2.5 6 .-{;.

t^ , _ 1 { ^ ` TEST DESCRIPTION Flight No. 2-51 „ TEST OB.?ECTIVES: Obtain definitive S/N and accuracy infor- i oration while flying below the peaks of surrounding mount,:ainous terrain near Mt.

Washington, Obtain additional. samples of S/N near power lines and plants. Overfly coastlines to detect any influence. Take } S/N measurements during maneuvers includ- ing a series of power on and power off stalls.

DATE: 20 April 1975 TIME : 1335 - 1710 EDT ORIGIN: Bedford DESTINATLON: Bedford ROUTE: Franconia., Whtefield, Bartlett, Libby, Bartlett, Saco, Shippin Light, Bedford ALTITUDE: 2500 ft for first mountain. circuit, 7000 ft for second WEATHER: VFR, clear 50 nor visibility becoming hazy l ! 1 ^ Flight No. 2-51 (Con's) SUMMARY: Flight proceeded well with waypoints with- - in 1/2 nm even in Franconia Notch. After clearing the notch the A-B LOP jumped one lane southwest or stopped incrementing.

Navigation. proceeded normally after sub- tracting 1 lane from A-B. No significant difference in weak signals at different altitudes. No weak signals after leaving mountains, during flight over powerlines.

No coast effects. Obvious weakening of S/N when radios were turned on.

^: ^' '

Appendix C INTERIP'i WARNIrIG SYSTEM PLAN FOR LOW COST OMEGA RECEIVER USERS m Users will requi-.e some form of local broadcast warn- ing such as an ATIS message or weather service announcement as to the current and expected status of the Omeg<^ system.

This message should include: enumeration of any stations at reduced power or that plan power reductions in the next 24 hours, any stations off the air or that plan periods of discontinuity of transmissions, any local signal. disturbances due to sudden ionospheric disturbances ar polar cap absorp- tions that are in progress or can be forecast from solar observationso A method of giving the pilot information as to system usability would be to assign a linear U-10 scale of signal strength and clarity for each station of nominal local use (e.g., four or five stations), Alternatively the ATIS . could give an Omega alert status (e.g., green, yellow, red) which would warn the pilot of c^^ndtions for proper navigation were marginal or bad, such that the pilot might then contact the weather service for a more complete description of system performance> The advent of differential Omega, which might be 1 i ^ rr an automated uplink to the receiver similar to DABS will allow uplink signals to light colored alert lid warn the pilot, or flash station letter lights to it particularly weak or non-transmitting station.. The sophisticated receivers might decode messages for a] numeric display to indicate directly to the pilot wY nature of the malfunction was.

DERIVATION OF h-VECTORS The h-vectors in hyperbolic navigation are gradients of lines of position with respect to changes in lattitude and longitude.. They are derived as follows: first the azimuths to the transmi ters from reception point are calcu- laced by - cos L sin ^^ x (Ref. 3) tan AX cos LX sin Lo cos ^a sin LX cos LQ - where x is the transmitter, o^the local position, L is lattitude, a is longitude, A is azimuth angle The property of the h-vector is .that it is always nor- mal to the local. LOP and in the direction of increasing L0: number ^,^..4^ 1 rA position 1 r B ^.

^^F .' hAB !,: . -1 rB ^ rA — rB ^ ^ SZ B Station Station i' ..

.. - ^ _ I rA I - ^ r B ^ hT = ar = lrA - 1rB The magnitude of the h-vector is then: ^^.

AB)I ^h ^ _ (2) ^ sin CAA cycles/local cycle ^- AB and its direction: ,{ + ^r / 2 B ) Z dAB - AAA + A to put the magnitude in the desired dimensions: 161,94807 c one 10.2 kHz cycle = ^ _ -.^^-- = 15.88 nm , anal ^^ ^ = I hAQ I c ycle hAB ^^.^$ nm It is then desired to generate the transformation matrix.: h2 ON DAB hl DE OBD h3 h4 change from point to point in A-B lanes where DAB = position =change in nm north = flat ^N =change in nm east = -^ lor. cos lat DE cos dAB h3 = ^IiBD ^ cos dBD hl = ^hAB^ (hAB^ sin d sin dBD h2 AB h4 = ^hBD^

L

f +f ^ i I REFERENCES 1. Hoffman, W. C., Howell, J. D., Hwoschinsky, P. V., and Wischmeyer, C. E., "Flight Evaulation of Omega Navigation in a General Aviation Aircraft," Aerospace Systems, Inc, Report No. ASI-TR-75-22, May 19750 2. Hoffman, W. C., Hollister ., W. H., and Howell, J. D., "Navigation and Guidance Requirements for Commercial VTOL Operations," NASA CR 132423, January 1974.

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