Instrument Landing System and Ancillary Electronic Component Configuration and Performance Requirements, With Change 1,2, and 3

3/29/12 6750.24E U.S. DEPARTMENT OF TRANSPORTATION FEDERAL AVIATION ADMINISTRATION ORDER National Policy 6750.24E Effective Date: 3/29/12 SUBJ: Instrument Landing System and Ancillary Electronic Component Configuration and Performance Requirements 1. Purpose. This order specifies the instrument landing system (ILS) and ancillary electronic component configuration and performance requirements for the various categories of low visibility flight operations.

2. Audience. The audience for this order is Federal Aviation Administration (FAA) personnel involved in the operations of all categories of ILS approaches, including approach procedures, operations, and ILS installation, maintenance, and monitoring.

3. Where You Can Find This Order. You can find this order on the MyFAA employee website at https://employees.faa.gov/tools_resources/orders_notices. Inspectors can access this order through the Flight Standards Information Management System (FSIMS) at http://fsims.avs.faa.gov. Air carriers (operators) can find this order on the FAA’s website at http://fsims.faa.gov. This order is available to the public at http://www.faa.gov/regulations_policies/orders_notices.

4. What This Order Cancels. This order cancels FAA Order 6750.24D, Instrument Landing System and Ancillary Electronic Component Configuration and Performance Requirements, dated March 21, 2000.

5. Scope. The requirements of this order apply to public Standard Instrument Approach Procedures (SIAP), identified special approach procedures, and lower-than-standard takeoff procedures (when applicable).

6. Definitions.

a. Continuity. The quality that relates to the rarity of radiated signal interruptions during any approach. The level of Continuity of Service (CoS) of the localizer and/or the glidepath is expressed in terms of the probability of not losing the radiated guidance signals.

b. Integrity. The quality that relates to the trust that can be placed in the correctness of the information supplied by the facility. The level of integrity of the localizer and/or the glidepath is expressed in terms of the probability of not radiating false guidance signals.

Distribution: Electronic Only Initiated By: AFS-400

5/11/20 6750.24E CHG 3 7. Explanation of Appendices.

a. Appendix A, Abnormal Checklist. Appendix A lists the basic ILS ground system components, explains the effect on operations when a component is abnormal or inoperative, and prescribes the action requirements.

b. Appendix B, Instrument Landing System (ILS) Classification System. Appendix B contains the ILS classification system, which was developed by the International Civil Aviation Organization (ICAO) All Weather Operations (AWO) Panel for guidance material in Annex 10 to the Convention on International Civil Aviation. The “Class” designation differentiates between the various performance capabilities of Types I, II, and III ILS equipment, including differences in performance between equipment generically classified as the same “Type.” 8. Issuance of Notices to Airmen (NOTAM). NOTAMs communicate ILS and ancillary component outages to pilots and air operators. Many outages require the issuance of a NOTAM (D) to inform operators of a facility or component outage and/or a related downgrade to authorized takeoff or landing operations as a result of that outage. However, some component outages may have differing effects based on the specific Instrument Flight Procedure (IFP) or other equipment available to the operator. For example, an inner marker (IM) failure only affects Category (CAT) II landing minimums at runways that do not have a published radio altimeter (RA) decision height (DH), which will be depicted on the procedure as “RA NA.” The majority of CAT II runways have a published RA DH. Therefore, close scrutiny is required to ensure that operations remain authorized to the fullest extent allowed by this order. When in doubt, contact the Flight Technologies and Procedures Division, Flight Operations Group, to determine the correct course of action.

a. Responsibilities. Generally, the owner or organization responsible for specific equipment is also responsible for issuing NOTAMs for that equipment. For example, the airport operator is typically responsible for issuing a NOTAM to notify pilots that runway centerline (RCL) lighting is out of service; Technical Operations is responsible for issuing a localizer out of service NOTAM; Flight Inspection is responsible for issuing the NOTAM to address any issue found on a flight check (refer to FAA Order 8200.1, United States Standard Flight Inspection Manual); and Flight Procedures is responsible for issuing procedural NOTAMs, such as flight data center (FDC) NOTAMs. Refer to the NOTAM rules for the specific line of business and FAA Order 7930.2, Notices to Airmen (NOTAM). For questions about operational issues that may occur due to an equipment outage, contact the Flight Operations Group.

b. Operation Levels in an Outage. Many operators are transitioning to performance-based operations, and different levels of operation may be authorized based on the flight and ground equipment available in the event of an outage. It is critical that required NOTAMs alert users of an inoperative facility or system. In some situations, an all-encompassing cancellation of specific minima (e.g., “CAT II/III Not Authorized”) may not be necessary. Many operators are authorized for some level of continued operations during outages of ground equipment such as marker beacons, runway lighting, approach lighting, or Runway Visual Range (RVR) sensors. In these situations, continued operations may be predicated on the use of specific equipment or procedures, which will be required in the operator’s authorization (such as an operations specification (OpSpec), management specification (MSpec), or Letter of Authorization (LOA)).

5/11/20 6750.24E CHG 3 Note: Ideally, a NOTAM will allow authorized operators to continue while notifying unauthorized operators that the specified approach procedure is not available. This supports accurate flight planning for both types of operators.

9. System Component Requirements. If an IFP must be amended due to a removed or never installed component, advise the Aeronautical Data Team (AJV-A31) and Flight Program Operations (AJF-1000).

a. Localizer and Glideslope.

(1) CAT II/III operations place a high degree of reliance on ILS guidance for positioning through touchdown, which requires specific integrity and CoS requirements as described in Appendix B. Most CAT II/III ILSs are equipped with dual transmitters and dual executive integrity monitors to meet these integrity and CoS requirements.

Note: FAA Order 8400.13, Procedures for the Evaluation and Approval of Facilities for Special Authorization Category I Operations and All Category II and III Operations, authorizes the use of single transmitter facilities for Special Authorization (SA) CAT II operations, provided the ILS meets all applicable CoS requirements. However, to date the FAA has not approved any single transmitter ILS facilities that meet II/D/2 integrity and CoS requirements.

(2) The following is the minimum class of performance (see Appendix B) required for an ILS to support a published Title 14 of the Code of Federal Regulations (14 CFR) part 97 CAT II or III SIAP: (a) Class II/T/2 for operations not less than RVR 1200.

(b) Class II/D/2 for operations not less than RVR 1000.

(c) Class III/D/3 for operations not less than RVR 700.

(d) Class III/E/3 for operations not less than RVR 600.

(e) Class III/E/4 for operations less than RVR 600.

(3) Class III/E/4 is required for takeoff operations less than RVR 500. Operators may be authorized takeoff minimums as low as RVR 300 via an operational authorization (OpSpec, MSpec, or LOA). These takeoff minimums require the use of an approved Head-Up Display (HUD) tracking a Class III/E/4 localizer. Flight Standards Service (FS) personnel should be aware of the potential impact on takeoff minimums created by a CoS issue or an outage that requires “CAT III NA” and consult the Flight Operations Group to determine the correct course of action. For example, RVR 300 takeoff operations may continue if a glideslope or Approach Light System (ALS) outage restricts ILS approach and landing operations and if the following requirements are met: (a) The localizer meets Class III/E/4 requirements, and air traffic control (ATC) protects the localizer critical area to support CAT III operations.

5/11/20 6750.24E CHG 3 (b) The taxiway lead-on lights serving the takeoff runway are operational.

(c) At least two RVR sensors are operational and reporting.

(d) High Intensity Runway Lights (HIRL) are operational.

(e) RCL lights are operational.

(4) To maintain the class of performance required for any given operation, the ILS must be flight inspected, and necessary maintenance inspections must be performed accordingly.

(5) Any ILS servicing a runway must be turned off throughout the duration of any scheduled runway closure to avoid hazardous safety risks. The glideslope must be shut down when a runway threshold is displaced or relocated. In that case, the localizer may continue to operate. During a runway closure, short periods of radiating the ILS are permissible for such tasks as routine maintenance and flight inspection. The radiation should be limited to the minimum extent practicable and a NOTAM (D) must be issued stating the ILS is not available.

Exceptions to this policy are allowed, when agreed to in writing by Operations Engineering, FS, Flight Procedures, and Terminal Services. Temporary runway closures of limited duration or that cannot practically be scheduled in advance represent a blanket exception to this policy, such as runway inspection, snow removal, or a disabled aircraft.

Note: Exceptions are appropriate when users and providers agree that there may be a procedural benefit to leaving the ILS in operation, such as improving air traffic services (circling minima, localizer-only minima, approach separation, etc.). Operations Engineering, FS, Flight Procedures, and Terminal Services rarely grant exceptions for glideslopes. For all exceptions, Technical Operations must ensure that construction activities will not degrade the ILS signals.

b. Marker Beacons . An Outer Marker (OM) or suitable substitute (see subparagraph 9c and Appendix A) is only required to indicate the final approach fix (FAF) for Nonprecision Approach (NPA) operations (i.e., localizer only). The FAF on CAT I/II/III ILS approach operations is the published glideslope intercept altitude, not the OM. Therefore, an OM or suitable substitute is not required for CAT I/II/III ILS approach operations. Middle marker (MM) beacons are not required for CAT I/II/III ILS. An IM is only required for CAT II operations below RVR 1600 that do not have a published RA minimum (see Appendix A). CAT II operations with a published RA minimum do not require an IM.

c. Compass Locator and Distance Measuring Equipment (DME). These aids increase operational flexibility and may support transition to the Final Approach Segment (FAS) or to define the Missed Approach Segment (MAS), based on the SIAP design. Also, they may substitute for the OM.

d. Localizer Far Field Monitor (FFM). This equipment provides additional monitoring of the localizer signal in the runway approach area. Although lengthy time delays (15 to 120 seconds typical) prevent nuisance alarms, the FFM is a useful indicator of critical area incursions and localizer antenna array problems not detected by the localizer integral monitors.

5/11/20 6750.24E CHG 3 Installation of FFM equipment is required to support most CAT II and III operations. Because of the high degree of reliance placed on the localizer for CAT III automatic landings, the FFM must be remotely monitored during CAT II/III operations.

Note: SA CAT II operations authorized by Order 8400.13 do not require an FFM.

e. RVR System.

(1) Other than CAT II/III. In all operations with RVR minimums other than CAT II/III (including nonprecision, approach procedures with vertical guidance (APV), and CAT I precision operations), the touchdown RVR is controlling when installed and operational. If the touchdown RVR is inoperative, an operator may be authorized (via OpSpec, MSpec, or LOA) to substitute an operative midpoint RVR for visibility minima greater than or equal to RVR 1800. If substitution is not authorized, reported visibility is controlling for these operations.

(2) CAT II. Touchdown RVR is required and controlling for all CAT II operations.

Where installed, midpoint and rollout RVR provide advisory visibility information to pilots. For CAT II operations less than RVR 1600, touchdown and a second RVR (either midpoint or rollout) must be installed. Touchdown, midpoint, and rollout RVR is an FAA system installation requirement for CAT II operations below RVR 1600 at runways in excess of 8,000 feet.

(3) CAT III. All CAT III operations require a touchdown, midpoint, and rollout sensor of an RVR reporting system. The Flight Technologies and Procedures Division may approve CAT III operations on a runway with only two RVR sensors (a touchdown and either a midpoint or rollout RVR sensor) on a case-by-case basis.

Note: Under specific circumstances, many operators are authorized for continued operations during a temporary outage of one RVR sensor if the remaining two RVR sensors are operational.

(4) RVR Sharing. RVR may be authorized on adjacent runways in accordance with the current Terminal Instrument Procedures (TERPS) standards and FAA Order 6560.10, Runway Visual Range (RVR).

f. ALS. If installed, this equipment supports reduced visibility minima for CAT I operations. An Approach Lighting System With Sequenced Flashing Lights (ALSF)-2, is normally required for CAT II and III operations. SA CAT II operations authorized by Order 8400.13 require an ALSF-1/ALSF-2, Simplified Short Approach Lighting System with Runway Alignment Indicator Lights (SSALR), or Medium Intensity Approach Lighting System with Runway Alignment Indicator Lights (MALSR) (with a threshold bar that is separate from the runway end lights). CAT II and III operations (including SA CAT II) may continue if the installed ALSF-2 is operating as an SSALR or Short Approach Lighting System (SALS), or if the MALSR is operating as a medium intensity approach lighting system (MALS), as described in Appendix A.

g. Touchdown Zone (TDZ) and RCL Lights. These lights are normally required for CAT II and III operations. SA CAT II operations authorized by Order 8400.13 do not require

5/11/20 6750.24E CHG 3 TDZ or RCL lights when using specific onboard equipment. The operator’s authorization specifies this equipment requirement and may allow continued CAT II operations if installed TDZ and/or RCL lights fail. CAT I operations below RVR 2400 require TDZ and RCL lights, except where onboard equipment substitution is permitted in lieu of TDZ and/or RCL lights. The IFP, the operator’s authorization, or both will note this onboard equipment requirement.

h. Runway Edge Lights. Edge lights are required for the approval of straight-in minima at night. A high-intensity capability is required for lower-than-standard takeoff minima, CAT I RVR minima, and all CAT II and III operations. A high-intensity incandescent capability (or equivalent) is required to support most operations utilizing infrared-based enhanced flight vision systems (EFVS).

i. Taxiway Lights. For FS approval of operations below RVR 500, at least one continuation of taxiway centerline lighting, extending from the runway to the ramp/apron area, is required. During operations below RVR 500, all taxiways that are illuminated must be equipped with controllable red stop bar lights at the appropriate runway holding position when the illuminated taxiway leads onto or across any runway being used. At each airport, a Surface Movement Guidance and Control System (SMGCS) plan lists approved taxiway lighting configurations and uses during light outages, and the airport or operator may have contingency plans in place in the event of taxiway lighting failure (e.g., follow-me vehicles).

10. Remote Monitoring Requirements.

a. General. FAA Order 8260.19, Flight Procedures and Airspace, defines four categories of Navigational Aid (NAVAID) monitoring and the utilization of those monitoring categories.

(These categories should not be confused with categories of flight operations.) The monitoring categories describe combinations of executive (capable of shutdown) and remote status monitoring. For an IFP to use a facility without limitation, both executive and remote status monitors must be operational (monitoring Category 1). Consult Order 8260.19 for additional details.

b. CAT II and III Operations.

(1) All ILS or ancillary electronic components that support CAT II and III operations must be monitored by personnel who are capable of determining whether the combined components’ capability can support continued operation following the loss or abnormal status of a required component. The monitoring personnel must be cognizant of the contents of this order and equipped to carry out the necessary action requirements promptly.

(2) The remote control/status indicator panel for a CAT II/III ILS is equipped with category status lights in addition to the standard equipment on/off/abnormal lights. The category status lights are intended to conveniently provide the operational status of the ILS to the local control personnel; that is, the lights enunciate the highest category of operation that the ILS is capable of supporting and will downgrade the category following the loss or change to abnormal status of a required system component. Although in some cases this downgrading is more stringent than that required in Appendix A, the category status lights must be considered valid and appropriate NOTAM action must be initiated, unless the following conditions can be met:

6/14/16 6750.24E CHG 2 (a) An airway transportation systems specialist is continuously monitoring the ILS equipment monitor panel. The panel must be displaying the status of all subsystems that normally provide electronic inputs to the category status light circuitry.

(b) The specialist has the capability to immediately communicate with air traffic or any other personnel assigned the responsibility of notifying the pilot of an inoperative component or change in operational status per the checklist in Appendix A.

(c) There is a written agreement between the local technical operations and air traffic personnel that the category status lights can be disregarded, that the specialist will monitor the required parameters and inform air traffic personnel of any change in equipment status, and that air traffic personnel will implement the checklist in Appendix A.

Note: A CAT II annunciation on the remote control/status indicator panel is not required at SA CAT II runways that do not have an FFM installed. This annunciation is due to the lack of the FFM and may be disregarded.

c. Visual Aid Lights.

(1) Runway edge, centerline, TDZ, and approach lights that support CAT II or III operations must be remotely monitored. Remote monitoring systems must be capable of detecting when more than 10 percent of the lights are inoperative. The lighting system/configuration must be considered inoperative when more than 10 percent of the lights are not functioning. For some systems, the system may be considered inoperative if two or more consecutive lights are inoperative. If the remote monitoring system is inoperative, an acceptable interim procedure is to station a cognizant person in a position to visually verify operation of runway edge, centerline, and TDZ lights during low-visibility operations who will immediately notify the controlling ATC element if they become inoperative. Additionally, Order 8400.13 allows the use of similar visual monitoring procedures in lieu of remote monitoring for runway edge lights, and allows the use of ALSs without any monitoring.

(2) Taxiway lights and individual airport/runway lights do not have to be remotely monitored. However, they must be inspected at an interval that assures that it would be very unlikely that no more than 10 percent of the lights and 2 adjacent lights would be inoperative, taking into consideration lamp life, environmental conditions, quality of power, etc.

11. Restoration Requirements. In some circumstances, maintenance action may be required to restore some or all categories of landing operations. Technical Operations will restore service in accordance with FAA Order JO 6030.31, National Airspace System Infrastructure Failure Response.

a. Reconciling Temporary Conditions. Order 8260.19 requires temporary conditions, such as lighting or NAVAID restrictions, to be reconciled as soon as possible so the temporary NOTAM can be canceled within a 224-day timeframe. If the condition cannot be corrected within 224 days, appropriate procedure amendments and/or airway revisions must be processed in accordance with Order 8260.19.

5/11/20 6750.24E CHG 3 b. CoS Outages. The benefits of maintaining low-visibility operational capabilities must be weighed against the risk of a greater downgrade for a longer period of time as a result of an additional CoS outage. Restorations following CoS outages should be considered carefully to avoid unnecessary operational impacts or impose additional reductions in the level of service.

For example, after the fifth CoS outage in the preceding 6 months, the ILS must be downgraded from Level 3 to Level 2 service. The technician should consult with their first level manager, who may consult with the ILS CoS Office of Primary Responsibility (OPR), to weigh the advantages and disadvantages of a return to Level 2 service.

c. Service Restoration. The advantage of a return to Level 2 service is continued CAT II operations, which may be necessary based on weather conditions and current operational needs.

In this situation, Level 3 service can be restored after a 4-week period that is free of outages.

However, a potential disadvantage is that the ILS will be further downgraded to Level 1 service if a CoS outage occurs within the next 4 weeks, which would require a 4-week period free of outages to restore Level 2 service, and an additional 2-week period to restore Level 3 service.

12. ILS Critical Areas. FAA Order 6750.16, Siting Criteria for Instrument Landing Systems, describes localizer and glideslope critical areas that must be marked and protected from parking and the unlimited movement of surface and air traffic to ensure the continuous integrity of the signal received by the user aircraft.

a. Longitudinal Axis. The entire length of the longitudinal axis of the aircraft must be clear of the critical area when conditions are such that the area must be protected. An aircraft with its longitudinal axis aligned with (parallel to) and outside of the edge of a critical area is not considered to be violating the critical area.

b. Ground Traffic in Critical Areas. The airport authority that controls ground traffic movements must assure that appropriate controls and devices are correctly located and that it has implemented specific holding instructions (when necessary) to protect the critical areas from ground traffic that is approaching or departing an active runway if the critical area dimension exceeds the distance of the normal runway holding position marking from the RCL. Where installed, taxiway centerline lead-off lights will be color-coded in accordance with Advisory Circular (AC) 120-57, Surface Movement Guidance and Control System, or AC 150/5300-13, Airport Design. For taxiways not equipped with centerline lights, a “Critical Area Boundary” sign may be installed on the reverse side of the ILS sign to indicate the critical area boundary.

c. Nonstandard Critical Areas. Where the standard critical area has a significant adverse impact on airport operations, such as specific taxi routes, it may be possible through operational constraints to provide relief on a case-by-case basis (e.g., considering the varying size of aircraft). Mathematical modeling techniques are available to facilitate this consideration.

13. Directive Feedback. Direct questions or comments regarding this order or minimum reduction for operations conducted with properly equipped aircraft to the Flight Operations Group at 202-267-8790. Note any deficiencies found, clarifications needed, or suggested improvements regarding the contents of this order on FAA Form 1320-19, Directive Feedback Information, and forward your comments to the Flight Operations Group for consideration. If an interpretation is needed immediately, call the Flight Operations Group for guidance and use FAA Form 1320-19 (included as the last page of this order) as a followup to verbal conversation.

6/14/16 6750.24E CHG 2 Appendix A Appendix A. Abnormal Checklist Maintenance Notify Facility Component Situation CAT Effect on Operation NOTAM (D) Required? Aircraft NOTAM Localizer (LOC) One I No effect. No No No No or Glideslope transmitter is II No effect—expedite corrective Yes No No No (GS) Transmitter inoperative maintenance.

III Denies operations. Yes Yes No “CAT III NA” LOC or GS Remote status I Refer to Order 8260.19, Yes No No Based on Remote Status monitor is paragraph 2-4-5, Monitoring of Order 8260.19 Monitor inoperative Navigation Facilities.

II & III Denies operations unless an Yes Yes Yes “CAT II/III NA” alternate method to continuously monitor the affected system(s) is implemented and aircraft can be informed immediately if a failure occurs.

Far Field Monitor At least All No effect. No No No No (FFM) Sensor(s) one sensor or Indicator (receiver subsystem) operating and not in alarm All sensors I No effect. No No No No (receiver II No effect. Yes No No No subsystems) inoperative III Denies operations. Yes Yes No “CAT III NA” A-1 6/14/16 6750.24E CHG 2 Appendix A Maintenance Notify Facility Component Situation CAT Effect on Operation NOTAM (D) Required? Aircraft NOTAM LOC or GS One monitor in a All No effect. No No No No Executive dual-channel (Integrity) system fails Monitors (excludes FFM function) Airport Traffic Unscheduled I No effect for minima at or above No Yes Yes “SA CAT I NA” Control Tower ATCT closure or Runway Visual Range (ATCT) otherwise not (RVR) 1800, denies Special controlling Authorization (SA) Category ground and (CAT) I operations below airborne traffic RVR 1800.

II & III Denies operations. No Yes Yes “CAT II/III NA” Outer Marker Inoperative All No effect on CAT I, II, and III Yes Yes Yes All nonprecision (OM) Beacon instrument landing system (ILS) (if operation is procedure(s) or operations. Nonprecision affected) minima where the operations that use an OM as a FAF cannot be final approach fix (FAF) cannot be identified by conducted if the FAF cannot be alternate means identified by alternate means, “NA” (see Navigational Aid (NAVAID), paragraph 8) radar, or published waypoint.

Middle Marker Inoperative All No effect. No Yes Yes No (MM) Beacon A-2 6/14/16 6750.24E CHG 2 Appendix A Maintenance Notify Facility Component Situation CAT Effect on Operation NOTAM (D) Required? Aircraft NOTAM Inner Marker Inoperative I No effect. No No Yes No (IM) Beacon II No effect if the aircraft is Yes (only if the Yes Yes Contact equipped to utilize radio altimeter SIAP does not Aeronautical (RA) minimum as published on have an RA Information the Standard Instrument Approach minimum) Services (AIS) for Procedure (SIAP). flight data center (FDC) NOTAM III No effect. No Yes Yes No RVR One or more I Inoperative touchdown zone No Yes Yes No RVR sensor is (TDZ) RVR sensor increases inoperative CAT I minima to one-half mile, except for operators who are approved to substitute an operative midpoint RVR sensor.

SA CAT I procedures not authorized.

II TDZ RVR is required for all Yes Yes Yes “CAT II NA” if the CAT II operations. TDZ RVR is inoperative III CAT III operations may continue Yes Yes Yes Issue a facility with one RVR sensor inoperative. NOTAM for all Two or more RVR sensors inoperative inoperative deny operations. RVR sensors.

Additionally, issue a “CAT III NA” NOTAM if two or more RVR sensors are inoperative.

A-3 6/14/16 6750.24E CHG 2 Appendix A Maintenance Notify Facility Component Situation CAT Effect on Operation NOTAM (D) Required? Aircraft NOTAM Approach Inoperative I Increases visibility to No Yes Yes “SA CAT I NA” Lighting (entire system) three-fourths mile or RVR 4000.

System (ALS) SA CAT I procedures not authorized.

II & III CAT II: Denies operations. Yes Yes Yes “CAT II NA” CAT III: No effect.

ALSF being I No effect. No Yes No No operated as simplified (SSALR) (or II & III No effect. Yes Yes Yes No ALSF sequenced flashing lights inoperative) ALSF or SSALR I Increases visibility to No Yes Yes No being operated as a three-fourths mile or RVR 4000.

short approach II & III No effect. Yes Yes Yes No lighting system (SALS), medium intensity approach lighting system with runway alignment indicator lights (MALSR) being operated as a medium intensity approach lighting system (MALS) A-4 6/14/16 6750.24E CHG 2 Appendix A Maintenance Notify Facility Component Situation CAT Effect on Operation NOTAM (D) Required? Aircraft NOTAM Power Source Main or standby I & SA No effect. No No No No for ALS (commercial) CAT II power source II & III CAT II: Denies operations unless Yes No No “CAT II NA” unless inoperative lights can be visually or remotely interim procedure monitored continuously and implemented aircraft can be informed immediately if a failure occurs.

CAT III: No effect.

Remote Monitor Remote monitor I & SA No effect. No No No No for ALS inoperative CAT II II & III CAT II: Denies operations unless Yes No No “CAT II NA” unless lights can be visually monitored interim procedure continuously and aircraft can be implemented informed immediately if a failure occurs.

CAT III: No effect.

Runway Edge Two consecutive I Day: Minima below RVR 2400 Yes Yes Yes Contact AIS for FDC Lights lights, or more not authorized. NOTAM issuance than 10% of the Night: Denies operations.

runway edge lights are not II & III Denies operations. Yes Yes Yes “CAT II/III NA” functioning Standby Power Inoperative I No effect. No No No No Source for II & III Denies operations unless lights can Yes Yes No “CAT II/III NA” Runway Edge be visually or remotely monitored unless interim Lights continuously and aircraft can be procedure informed immediately if a failure implemented occurs.

A-5 6/14/16 6750.24E CHG 2 Appendix A Maintenance Notify Facility Component Situation CAT Effect on Operation NOTAM (D) Required? Aircraft NOTAM Remote Monitor Inoperative I No effect. No No No No for Runway II & III Denies operations unless lights can Yes Yes No “CAT II/III NA” Edge Lights be visually monitored unless interim continuously and aircraft can be procedure informed immediately if a failure implemented Runway TDZ Two adjacent I Refer to Inoperative Components No Yes Yes No Lights crossbars, or and Visual Aids Table.

more than 10% II Reduced lighting CAT II Yes Yes Yes “NAV ILS RWY XX of either side of operations authorized. Operators REDUCED LGT the runway TDZ require specific OpSpec, MSpec, SPECIAL AUTH lights are not or LOA approval and use of CAT II AVAIL” functioning autoland or Head-Up Display (HUD) to touch down.

III Denies operations. Yes Yes Yes “CAT III NA” Runway Four consecutive I Increases RVR to 2400, unless the No Yes Yes No Centerline lights, or more operator uses a flight director or (RCL) Lights than 10% of the autopilot or HUD to decision RCL lights are altitude (DA).

not functioning II Reduced lighting CAT II Yes Yes Yes “NAV ILS RWY XX operations authorized. Operators REDUCED LGT require specific OpSpec, MSpec, SPECIAL AUTH or LOA approval and use of CAT II AVAIL” autoland or HUD to touch down.

III Denies operations. Yes Yes Yes “CAT III NA” A-6 6/14/16 6750.24E CHG 2 Appendix A Maintenance Notify Facility Component Situation CAT Effect on Operation NOTAM (D) Required? Aircraft NOTAM Stand b y P ower Inoperative I No effect. No No No No Source for II No effect. Yes No Yes No Runway TDZ Lights or III Denies operations. Yes Yes Yes “CAT III NA” RCL Lights Remote Monitor Inoperative I No effect. No No No No for Runway II No effect. Yes No Yes No TDZ Lights or RCL Lights III Denies operations. Yes Yes Yes “CAT III NA” Note: Where the action requirement is to inform the aircraft of the inoperative component situation, do so in accordance with FAA Order JO 7110.65, Air Traffic Control, paragraphs 3-3-3, Timely Information, and 4-7-12, Airport Conditions. Pilots will adjust minima/discontinue operations predicated on the inoperative component notification in accordance with the Inoperative Components and Visual Aids Table, the approved OpSpecs, MSpecs, and/or FAA LOA.

Note: Where the action requirement is to initiate a NOTAM to disallow the operation, do so in accordance with FAA Order JO 7930.2, Notices to Airmen (NOTAM), in the sections on Navigational Aid (NAVAID), Communications Outlets, and Services.

Note: “CAT” indicates the operation being conducted or approved.

Note: When the action requirement is “CAT II NA,” both standard CAT II and SA CAT are not authorized.

Note: At sites where it is impractical to monitor lights continuously, the lights must be monitored at intervals of no more than 8 hours.

A-7

3/29/12 6750.24E Appendix B Appendix B. Instrument Landing System (ILS) Classification System 1. Purpose of the ILS Classification System. The ILS classification system specified in this appendix provides a more comprehensive method of describing ILS performance than the Facility Performance Category (CAT) method alone.

2. Class Definitions. A facility’s “Class” of performance is defined by using three characters as follows: a. I, II, or III. The first character indicates conformance to the Facility Performance CAT standards contained in International Civil Aviation Organization (ICAO) Annex 10, unless superseded by an FAA directive.

b. A, B, C, T, D, or E. The second character defines the ILS point to which the localizer conforms to the Facility Performance CAT III course structure tolerances. These classifications indicate ILS conformance to a physical location on the approach or runway as follows: • A: 4 nautical miles (NM) before the threshold; • B: 3,500 feet before the threshold (CAT I decision point); • C: Glidepath altitude of 100 feet height above touchdown (HAT) (CAT II decision point); • T: Threshold; • D: 3,000 feet beyond the threshold (CAT III requirement only); and • E: 2,000 feet before the runway end (CAT III requirement only).

Figure 1. Instrument Landing System Reference Points and Bend Limits B-1 3/29/12 6750.24E Appendix B c. 1, 2, 3, or 4. The third character indicates the minimum level of integrity and Continuity of Service (CoS) given in Table 1, Minimum Localizer and Glideslope Integrity and Continuity Levels. Refer to FAA Order JO 6750.57, Instrument Landing System Continuity of Service Requirements and Procedures.

(1) Level 1-rated ILS equipment supports low-visibility operations for which positioning guidance below approximately 200 feet height above threshold (HATh) is supplemented by other means, such as visual cues or advanced avionics.

(2) Level 2-rated ILS equipment supports reduced visibility operations for which positioning guidance below 100 feet HATh is supplemented by other means, such as visual cues.

(3) Level 3-rated ILS equipment supports operations that place a high degree of reliance on ILS guidance for positioning through touchdown.

(4) Level 4-rated ILS equipment supports operations that place a high degree of reliance on ILS guidance throughout touchdown and rollout, or for low-visibility takeoff operations that require a localizer for lateral guidance throughout the takeoff roll.

3. Class Explanations and Examples. As an example, an ILS that conforms to the ICAO Annex 10 Facility Performance CAT III standards, meets the CAT III localizer course structure criteria to ILS point “D,” and conforms to the integrity and CoS objectives of Level 3 would be described as “Class III/D/3.” An ILS that conforms to ICAO Annex 10 Facility Performance CAT I standards, has a localizer CAT III course structure to point “E,” and conforms the integrity and CoS objectives of Level 2 would be described as “Class I/E/2.” However, when Facility Performance standards are monitored to CAT II standards, this same facility having a localizer CAT III course structure to point “E” and conforming to the integrity and CoS objectives to Level 2, would be described as “Class II/E/2.” Table 1. Minimum Localizer and Glideslope Integrity and Continuity Levels Level Integrity Continuity MTBO (Hours) 1 Not demonstrated, or less than required for Level 2 -7 -6 1 - 1x10 in any 1 - 4x10 in any period of 2 1000 one landing 15 seconds -9 -6 1 - 0.5x10 in any 1 - 2x10 in any period of 3 2000 one landing 15 seconds -6 1 - 2x10 in any period of: -9 1 - 0.5x10 in any 4000 (LOC) 4 30 seconds (LOC) one landing 2000 (GS) 15 seconds glideslope (GS) B-2 3/29/12 6750.24E Appendix B Note: Some earlier design ILS equipment types have been determined to require minimum demonstrated Mean Time Between Outages (MTBO) performance and/or manual integrity tests to conform to the integrity and continuity level requirements of Table 1. Order JO 6750.57 describes how ILS equipment must meet the MTBO criteria in Table 1 and includes the method for calculating MTBO.

Note: Attachment C to Part 1 of ICAO Annex 10, Volume I, contains additional information on integrity and CoS.

B-3 Directive Feedback Information Please submit any written comments or recommendation for improving this directive, or suggest new items or subjects to be added to it. Also, if you find an error, please tell us about it.

Subject: FAA Order 6750.24E CHG 3, Instrument Landing System and Ancillary Electronic Component Configuration and Performance Requirements To: Flight Standards Directive Management Officer, AFB-120 Directives Mailbox (9-AWA-AFB-120-Directives@faa.gov) (Please check all appropriate line items) An error (procedural or typographical) has been noted in paragraph __________ on page ____________ .

Recommend paragraph ____________ on page _________ be changed as follows: (attach separate sheet if necessary) In a future change to this order, please cover the following subject: (briefly describe what you want added) Other comments: I would like to discuss the above. Please contact me.

Submitted by: _________________________________ Date: _____________ Telephone Number: ___________________ Routing Symbol: _______________ FAA Form 1320-19 (10-98)