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HUMAN SURVIVAL I N
AIRCRAFT EMERGENCIES
by Churles A. Y o s t und Ronuld W. Outes
' ' _ i I :&% Prepared by , .
. . . . .
, : STENCEL AERO ENGINEERINGCORPORATION .,-.
Asheville, N . C.
for NATIONAL AERONAUTICS AND SPACE A D M I N I S T R A T I O N WASHINGTON, D. C. J A N U A R Y 1 9 6 9 - -
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TECH LIBRARY KAFB, N M 00b05b9 NASA CR-1262
I N AIRCRAFT EMERGENCIES
HUMAN SURVIVAL By Charles A. Yost and Ronald W. Oates
Distribution of this report is provided in the interest of
informationexchange.Responsibilityforthecontents resides in the author or organization that prepared it.
Prepared under Contract No. NASw-1530 by STENCEL AERO ENGINEERING CORPORATION Asheville, N.C .
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NATIONAL AERONAUTICSANDSPACEADMINISTRATION For sale b y the Clearinghouse for Federal Scientific and Technical Information Springfield,Virginia 22151 - CFSTl price $3.00
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ABSTRACT A g e n e r a ls t u d y w a s p e r f o r m e dt oo u t l i n em e t h o d sf o rt h e i m p r o v e m e n to fh u m a ns u r v i v a li nc i v i l i a na i r c r a s t emer- g e n c i e s . S u r v i v a l c o n d i t i o n c r i t e r i a , a c c i d e n t s t a t i s t i c s a n dh u m a nt o l e r a n c e limits h a v eb e e ns u r v e y e dw i t hr e s p e c t t ot h o s ea i r c r a f tu s e di nt w oc a t e g o r i e s :c e r t i f j c a t e d a i r c a r r i e r sa n dg e n e r a l - p r i v a t ea v i a t i o n( i n c l u d i n go f f i c i a l e x e c u t i v ea i r c r a f t ) .T h em e t h o d sp r e s e n t e di nt h i sr e p o r t f o r a i r c r a f t o c c u p a n ts u r v i v a l+ m p r o v e m e n tf a l li n t ot h e g e n e r a l a r e a s o fo c c u p a n tp r o t e c t i o nt h r o u g h s e a t d e s i g n a n do c c u p a n tr e s t r a i n t- i m p r o v e m e n tt ow i t h s t a n di m p a c t a c c e l e r a t i o n s w h i c h a r e a p p l i e dt ot h e a i r c r a f t .
iii ,/
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F O R E W O R D This volume b r i e f l y d e s c r i b e s how s u r v i v a l i n aircraft emergenciescan be improvedby optimum aircraft i n t e r i o r and seat systemdesign t o a i d o c c u p a n t r e s t r a i n t , s u p p o r t and p r o t e c t i o n .T h i s effort is conductedunderthe Life Support and P r o t e c t i v e Systemssubprogram of t h e Human FactorsSystems
Program, a l i n e i t e m of the Congressional Authorization t o t h e
National Aeronautics and Space Administration.
As a follow-on e f f o r t t h e A m e s Research Center, Mof f e t t F i e l d , C a l i f o r n i a , is conducting for t h e Human F a c t o r s Program a developmentaleffort t o design,develop, and e v a l u a t e a p r o t o t y p e s e a t / r e s t r a i n t s y s t e m f o r improved crash and v i b r a t i o n p r o t e c t i o n . The latest developments i n energy-absorption tech- n i q u e s , p r o t e c t i v e s t r u c t u r e s , andfull-body emergency r e s t r a i n t methods w i l l be a p p l i e d t o t h e problem. , - V ACKNOWLEDGMENTS The research study described herein was conducted by Stencel Aero Engineering Corporation under NASA Contract NASw-1530. The work was of Dr. W. L. Jones, Director, Biotechnology and done under the auspices Human Research Division and technical direction of Mr. Allan Merkin, NASA Headquarters, Washington, D.C.
Aircraft and accident statistics have been provided by the FAA and interpreted by the writers for graphical presentation.
Definition of the most adverse environments in which a human might survive have been abstracted from the FAA-Civil Aero- medical Research Institute work, from NASA reports and the Flight Safety Foundation, Inc. test data. In addition, a number of agencies and investigators have been consulted in an effort to gain in-depth information rapidly for this report.
These contacts have included: 1. NASA- Biotechnology and Human Research Division, Washington, D.C.
2. FAA - Mr. J. J. Swearingen, and Mr. A. H.
Hasbrook, civil Aeromedical Research Institude, Oklahoma City, Oklahoma 3. FAA - M r . J. J. Carroll, Supersonic Transport-Safety Washington, D. c.
4 . CAB - Mr. B. R . Allen and Mr. Hollowell, Bureau of Safety, Washington, D.C.
5. Mr. J. Lederer and Mr. Hallas, Flight Safety Foundation, Inc., Phoenix, Arizona 6 . Dr. L. S. Higgins, M.D., Technology, Incorporated, San Antonio, Texas 7. Mr. J. H. Enders, NASA, Aeronautics Division, Washington, D. c.
vii TABLE OF CONTENTS SUMMARY 1 INTRODUCTION
SURVIVAL CRITERIA
Survivable Aircraft Accidents Crashworthiness Occupant Flailing Human Body Structure
AIRCRAFT EMERGENCY SURVIVAL METHODS 1 2
INTERNAL FUSELAGE IMPROVEMENTS 13 Occupant Protection & Interior Design Methods 1 4 Seat Design Restraint Design COMMERCIAL MULTI-ENGINE TRANSPORT S A F E T Y IMPROVEMENT General Statistical Information Transport Aircraft Seating & Restraint System Improvement 26 Energy Absorbing Seat Development 2 8 Integrated Safety Seat Honeycomb Design for Impact Survival GENERAL AVIATION S A F F T Y IMPROVEMENT General Aviation Statistics 34 INTERNAL IMPROVEMENTS Seat Attachment 4 2 HUMAN TOLERANCES REFERENCES 53 ix . " SUMMARY S u r v i v a li na i r c r a f te m e r g e n c i e sc a nb ei m p r o v e d ,g e n e r a l l y s p e a k i n g , b yi m p r o v e da i r c r a f ti n t e r i o ra n d s e a t d e s i g nt o a i do c c u p a n tr e s t r a i n ta n dp r o t e c t i o n .T h i sw o u l dr e d u c e i n j u r i e sa n df a t a l i t i e si nt h o s ea c c i d e n t si nw h i c ht h e a i r - c r a f ti n c u r ss u b s t a n t i a ld a m a g eb u tn e v e r t h e l e s sr e m a i n sa d - e q u a t e l yi n t a c tf o ro c c u p a n ts u r v i v a l .
T h i sr e p o r te m p h a s i z e so c c u p a n ts e a t i n ga n dr e s t r a i n t i m - p r o v e m e n t as r e l a t e d t o : ( 1 ) c e r t i f i c a t e d a i r c a r r i e rt r a n s p o r ta i r c r a f t h a v i n gl a r g ep a s s e n g e rc a p a c i t y , ( 2 ) g e n e r a l / p r i v a t e a v i a t i o n a i r c r a f t h a v i n g a f e wo c c u p a n t s .
A i r c r a f ta c c i d e n ts t a t i s t i c ss h o wt h a ts u b s t a n t i a ld a m a g e i s s u s t a i n e di nn e a r l y 7 0 p e r c e n to f a l l a i r c r a f ta c c i d e n t sb u t t h a tt h ef u s e l a g er e m a i n ss u f f i c i e n t l yi n t a c tf o r human s u r - v i v a l .O c c u p a n t sc a nb ep r o t e c t e da g a i n s ti n j u r yi nt h i st y p e o fa c c i d e n tb ym e a n so fe n e r g ya b s o r p t i o n s e a t d e s i g n s ,p r o - t e c t i v e s e a t s t r u c t u r ew i t hi m p r o v e df u l lb o d yr e s t r a i n ' t ,a n d s a f e t y c o n s c i o u s n e s s i n i n t e r i o r c a b i n d e c o r . I n t e r n a l i m p r o v e - m k n t sw o u l dt h e r e f o r eh a v eb e n e f i c i a lu t i l i z a t i o ni nt h e m a j o r i t yo fa i r c r a f ta c c i d e n t sa n dp r o v i d ei m m e d i a t e a r e a s f o r i m p r o v e m e n t .
INTRODUCTION
The civil Aeronautics Board classifies an aircraft accident as the occurrenceincident to flight in which, as a result of the operation of an aircraft, any person (occupant or non-occupant) receives fatal or serious injury,or any aircraft receives sub- stantial damage. h aircraft accident incident to flight is further defined as an accident which occurs between the time an engine orengines are started for the purpose of commencing flight until the aircraft comes to rest with all engines stopped for complete or partial deplaning or unloading. It excludes death or injuries to persons on board which result from illness, altercations, and other incidents not directly attributable to flight operations. This report refers to an aircraft emer- gency as a situation in which an aircraft accident results.
The problem of improving the chance of human survival in air- craft emergencies arises out of the increasing numbers of persons using aircraft as well as the widely diversified per- formance and application of these aircraft. The provision of survival aids to meet an aircraft emergency have not kept pace with the capability of an aircraft to transfer people into environmental conditions beyond human tolerance. The problem is most acute in all fields of civil aviation where manufactur- ing and operating economics are strong factors.
This report presents concepts, analyses, and evaluation of prac- tical survival methods that maybe applied to civilian aircraft.
Two categories of aircraft have been considered in the study: (1) certificated air carrier aircraft, and ( 2 ) general private aviation aircraft (including executive official aircraft.)
Consideration is given to human tolerance, aircraft impact vel- ocity and angle, the type of aircraft operation, the accident statistics that indicate predominate problem areas, and survival improvement concepts that can be applied inside of the aircraft t o accomplish human protection.
The study as reported, proceeds first to define the extent of the survival improvement problem in terms of aircraft accident statistics; and in terms of physical factors such as velocity, acceleration, and human tolerance.
Thereafter, methods for survival improvement are presented that would be applied internal tc the aircraft to maintain conditions of occupant tolerance by means of seat design and occupant res- traint, SURVIVAL CRITERIA S u r v i v a b l e A i r c r a f t A c c i d e n t s T h e r e a r e m a n yc o n d i t i o n st h a ta no c c u p a n t i s e x p o s e d t o a n d m u s tw i t h s t a n di no r d e rt os u r v i v ea na i r c r a f ta c c i d e n t .
A s s u m i n gt h ea i r c r a f tf u s e l a g er e m a i n ss t r u c t u r a l l yi n t a c t , t h ep a s s e n g e rm u s tb ep r o t e c t e df r o ms e v e r ei m p a c tf o r c e s , s m o k e ,f i r ea n df u m e s ,a n dt h e nh em u s tb eg i v e n a m e a n s f o r i m m e d i a t e e v a c u a t i o n . T h e f i r s t a n d f o r e m o s t r e q u i r e m e n t t o b e m e t i no r d e rf o rt h eo c c u p a n tt os u r v i v e i s t h a t t h e a i r c r a f t f u s e l a g e m u s t r e m a i n s u b s t a n t i a l l y i n t a c t . W h i l e f i r e sm u s tb es u p r e s s e da n dt h ep a s s e n g e r sm u s tb ep r o t e c t e d f r o ms m o k ea n df u m e s , a n dt h e ne v a c u a t e d ,n o n eo ft h e s ec a n b ev e r yu s e f u lw i t h o u tm a i n t a i n i n gs t r u c t u r a li n t e g r i t yo f t h eo c c u p a n t a r e a .
T h i sr e p o r td e a l sp r i m a r i l yw i t ht h ep r o b l e mo fp r o t e c t i n g t h e a i r c r a f t o c c u p a n t s f r o m s e v e r e i m p a c t f o r c e s . A s u r v i v a b l e a i r c r a f ta c c i d e n t i s t h e r e f o r ed e f i n e df o rt h i ss t u d y as o n ei n w h i c ht h eo c c u p i e dc o c k p i ta n d / o rf u s e l a g er e m a i nr e l a t i v e l y w h o l e a f t e r i m p a c t . T h e m e t h o d s s t u d i e d a n d p r e s e n t e d i n t h i s r e p o r t a r e t h e r e f o r ec o n c e r n e dw i t ho c c u p a n ts t r u c t u r a lp r o - t e c t i o n ;a n di m p r o v i n gt h eo c c u p a n t s e a t a n dr e s t r a i n ts t r u c - t u r e s o a s t ob ec o m p a t i b l ew i t hh u m a ni m p a c ta n da c c e l e r a t i o n t o l e r a n c e s .
Two a s p e c t so fs u r v i v a lc r i t e r i ae x i s t .O n eh a st od ow i t ht h e a i r c r a f ts t r u c t u r ec a p a b i l i t ya n dt h eo t h e rh a st od ow i t ht h e o c c u p a n t - s e a t s t r u c t u r a l c a p a b i l i t y . S i n c e t h e i m p o s e d f o r c e s a r e d e p e n d e n tu p o nt h ev e l o c i t yc h a n g e st h a to c c u rw i t hd i s t a n c e a n d t i m e , i t i s p o s s i b l et op r e s e n tt h e l i m i t s o fs t r u c t u r a l c a p a b i l i t yi nt h e s e t e r m s . S i m i l a r l y , t h e o c c u p a n t h a s a c c e l e r a - t i o n t o l e r a n c e s b e y o n d w h i c h h e s u s t a i n s i n j u r y . An e s t i m a t e o ft h e s el i m i t a t i o n s a r e g i v e ni nF i g u r e 1, a n de x p r e s s e di n t e r m s o fv e l o c i t yc h a n g ea n dd e c e l e r a t i o nd i s t a n c e .
A s s h o w ni nF i g u r e 1, o n e r e a l limit p l a c e du p o nt h eo c c u p a n t i s t h a ta v a i l a b l ed i s t a n c eu n d e rw h i c hh e m a y b ed e c e l e r a t e d .
T h i s l i m i t i s p l a c e du p o nt h eo c c u p a n t b y s u r r o u n d i n g s e a t s , b yt h ec o c k p i te n v e l o p e ,o r by t h ed i s t a n c e .f r o mt h eb o t t o mo f t h e s e a t t ot h ef l o o r .T h eo c c u p a n tm u s tb ed e c e l e r a t e dw i t h i n t h i ss p a c el i m i t a t i o n .
Data o nt h ea c c e l e r a t i o nt o l e r a n c eo ft y p i c a la i r c r a f to c c u p a n t s ( m e n , women a n d c h i l d r e n ) i s n o t a v a i l a b l e . W h i l e i t i s known t h a ts o m ep e r s o n sh a v ee x p e r i e n c e da n dt o l e r a t e dv e r yh i g h acceleration forces, with a wide variety of passengers a 10 g limitation would be reasonable for design. With a 10 g limit- ation for design and the space available to the seat for displacement it can be seen in Figure1 that the relative occupant velocities with objects in the cabin should be limited to about 25 ft/sec. Velocities in excess 0% this amount are likely to cause injury to the passenger.
Crashworthiness Figure 1 gives some idea of the limits for aircraft structure and for occupants under a crash environment. The aircraft longitudinal deceleration distance covers a wide range because of various horizontal sliding resistance conditions. Hori- zontal velocities in excess of about 180 ft/sec. might be tol- erated by the aircraft provided it does not meet strong vertical obstacles, steep embankments, o r have severe attitudes. Sliding action permits the deceleration distance in the longitudinal direction to be much larger than the actual length of the air- craft. Objects approached longitudinally may often result in the fuselage remaining relatively intact.
The ability of the aircraft fuselage to attenuate vertical vel- ocity is fixed by the fuselage diameter. Vertical velocity tolerance is therefore much less than that for the longitudinal direction. The only means attenuating the vertical velocity is crushing of the aircraft diameter. rn the case of most trans- ports, perhaps four o r five feet of fuselage can be deformed before the interior cabin floor structure reaches ground level.
As illustrated in Figure 1 , this deformation might allow a 3 0 o r 4 0 foot per second vertical velocity to be tolerated and still maintain reasonable occupied fuselage structural integrity.
Approximate survivable impact conditions found in some transport crashes investigated by Av-Ser (reference 3 and 7 ) were as follows: 150 knots forward speed 15 degrees nose down pitch angle 30 degrees yaw angle to either side of the longitudinal axis of the aircraft.
a resultant crash force angle within an arc extend- ing from 1 5 degrees above to 45 degrees below the longitudinal aircraft axis in the vertical plane and parallel to the longitudinal axis.
impact against and a deceleration on reasonably level terrain having the general density of plowed ground.
T h e s ec o n d i t i o n s a r e g e n e r a l l yi nk e e p i n gw i t ht h o s eo u t l i n e di n F i g u r e 1. T h e v e l o c i t y a n d i m p a c t a n g l e a t w h i c h t h e f u s e - l a g ec o m m e n c e st ou n d e r g os e v e r ed e s t r u c t i o n i s s h o w ni nF i g u r e2 .
T h i s i s r o u g h l yc o m p a t i b l ew i t ht h eA v - S e rf i n d i n g sf o rs u r v i v a b l e - u n s u r v i v a b l ec o n d i t i o n sf o u n di ns o m et r a n s p o r t s ; as w e l l as b e i n g r o u g h l y c o m p a t i b l e w i t h F i g u r e 1. T ot h i sd a t e ,v e r y l i t t l e t e s t d a t a i s a v a i l a b l et h a tw o u l da l l o w a m o r ee x a c td e f i n i t i o no f t h es u r v i v a b l ea c c i d e n tb o u n d a r i e sf o ra i r c r a f ts t r u c t u r e s .
L o o k i n g a t F i g u r e 2 i t c a nb es e e nt h a tt h er e g i o nf o rs u r v i v - a b i l i t y e x t e n d s u p t o a n a i r c r a f t v e l o c i t y o f a b o u t 1 4 0 m i l e s p e rh o u rf o rh o r i z o n t a li m p a c ta n g l e s . A s t h ef l i g h tp a t h a n g l ei n c r e a s e st h et o l e r a t i o no ft h ea i r c r a f td e c r e a s e s ,u n t i l a t a b o u t 7 0 d e g r e e s ,t h et o l e r a b l ev e l o c i t yp r o b a b l yd r o p st o n e a rz e r o .
O c c u p a n tF l a i l i n g D e s i g ni m p r o v e m e n tf o ro c c u p a n tp r o t e c t i o nr e q u i r e st h a ts p a c e b ea v a i l a b l ef o rt h eo c c u p a n tt od e c e l e r a t e ,a n dr e q u i r e sf u l l r e s t r a i n to ft h eo c c u p a n ti nh i s s e a t ( r e f e r e n c e 3.4, 3 . 5 ) .
I nc u r r e n ts e a t s , p a r t i c u l a r l yi ng e n e r a la v i a t i o n ,c a b i nc o n d i - t i o n s a r e p r e v a l e n tt h a tc a u s et h eo c c u p a n tt ob e c o m ei n j u r e d f r o mi m p a c tw i t hr i g i ds t r u c t u r e s .
Case h i s t o r i e ss h o wt h a t 7 0 t o 8 0 p e r c e n to f a l l g e n e r a la v i a t i o n i n j u r i e si nc r a s hd e c e l e r a t i o n s a r e a r e s u l t of f a c eo rh e a d i m p a c t s c a u s e d by u p p e r t o r s o a n d h e a d f l a i l i n g . I m p r o v e d o c c u p a n tr e s t r a i n td e s i g ni n c o r p o r a t i n gu p p e rt o r s or e s t r a i n t w o u l di m m e d i a t e l yd e c r e a s et h ei n j u r yi n d e xi nt h e s es u r v i v a b l e c r a s h e s .
T op r o v i d es o m ei d e ao ff l a i l i n gs w e e p ,F i g u r e 3 s h o w st h e m o t i o n so ff i f t ha n dn i n e t y - f i f t hp e r c e n t i l es u b j e c t sa c c e l e r a t e d f o r w a r d o v e r a t i g h t s a f e t y b e l t . R e f e r e n c e 2 . 2 , 2 1 5 . T h e s u b j e c t s w e r e d i s p l a c e db y a 1 g f o r c e s o t h es w e e pp r e s e n t e d m u s t b e c o n s i d e r e d as a minimum s t r i k ed i s t a n c e .T h ei m p a c t v e l o c i t yo ft h eh e a dd u r i n gt h e s e t e s t e x c e e d e d1 2f t / s e c .
I na c t u a lc r a s hc o n d i t i o n sl a r g e rm a g n i t u d e so fb o d ym o v e m e n t c a n b e e x p e c t e d s i n c e i m p a c t f o r c e s a r e l i k e l y t o b e 1 g a n dt h ep a s s e n g e r s e a t b e l t sw o u l dp r o b a b l y g r e a t e rt h a n b e l o o s e l y f a s t e r . a d . W h i l e i t i s n o t p r a c t i c a l t o a l l o w a m o u n to fs p a c en e e d e d s o t h a tt h eo c c u p a n tc o u l df l a i lw i t h o u t i m p a c t i n ga n ys t r u c t u r e , it i s p r a c t i c a lt or e s t r a i nt h eo c c u p a n t s u c ht h a th i sh e a da n dt o r s o a r e u n a b l et of l a i l .S h o u l d e ra n d l a pr e s t r a i n ta l o n ew o u l de l i m i n a t e a l a r g en u m b e ro fi m p a c t i n j u r i e s .
F i g u r e3 ( b )i l l u s t r a t e st h en u m b e ro fi n j u r i e st h a th a v eb e e n i n c u r r e do nv a r i o u sp a r t so ft h eb o d yi n a l a r g en u m b e ro fl i g h t a i r c r a f ta c c i d e n t s .T h i si n j u r yp a t t e r no f 800 s u r v i v o r si n l i g h ta i r c r a f ta c c i d e n t ss h o w st h a t ,i nl i g h tp l a n e s a t l e a s t , t h eg r e a t e s tn u m b e ro fi n j u r i e so c c u rt ot h eh e a da n dt o r s o .
T h i s i s a l m o s te n t i r e l y a r e s u l to fb o d yf l a i l i n g a t i m p a c t .
T h en e e dt or e s t r a i n t h e b o d y a b o v e t h e w a i s t i s a p p a r e n ta n d s h o u l db ei n c o r p o r a t e d .
Human Body S t r u c t u r e t h e r i g i df r a m e w o r kf o r t h e b o d yt o c a r r y l o a d s B o n e sp r o v i d e a n dt op r o t e c tt h ev i t a lo r g a n ss u c h as t h eh e a r t ,b r a i n ,a n d l u n g s f r o m i n j u r y . T h e l i g a m e n t s a c t t o h o l d t h e b o n e j o i n t s t o g e t h e ra n dc a r t i l a g ef u r n i s h e s e l a s t i c c o n n e c t i v et i s s u e s w h i c hp r o t e c tt h eb o n e s a t t h ej o i n t sf r o ms h o c ka n dg i v et h e s k e l e t o n m o r e f l e x i b i l i t y . F i g u r e 4 i l l u s t r a t e st h ea r r a n g e - m e n to ft h eh u m a ns k e l e t o n ,a n di d e n t i f i e st h em a j o r s k e l e t a l p a r t s by t h e i rt e c h n i c a ln a m e s .
T h ee n g i n e e r i s c o n c e r n e dw i t ht h eb o d y as a s t r u c t u r a ll o a d c a r r y i n g s y s t e m f o r d y n a m i c a n d s t a t i c l o a d s . T h e b o d y , b e i n g a c o m p o s i t eo ff l e x i b l yc o n n e c t e dr i g i dm e m b e r s ,m u s tb e e x t e r n a l l yr e s t r a i n e dt op r e v e n te x c e s s i v e momentum o rf o r c e t ob u i l du pb e t w e e nt h ep a r t s .F o r a s e a t e da i r c r a f tp a s s e n g e r u n d e r g o i n gr a p i dd e c e l e r a t i v ef o r c e s ,t h eb o d y masses r e q u i r i n g r e s t r a i n t a r e t h ep e l v i sr e g i o n ,t h eu p p e rc h e s t a r e a a n dt h e h e a d .W h i l er e s t r a i n to ft h e arms a n d l e g s w o u l d a l s o b e d e s i r a b l e ,m o v e m e n to ft h e s eb o d yp a r t sa n dt h e i rp o s s i b l ei n - j u r y a r e n o td i r e c t l y f a t a l . W h i l em e t h o d sf o rs u c ht o t a l r e s t r a i n tw o u l db ed e s i r a b l e , i t w o u l dp r e s e n tm u c hd i f f i c u l t y i n p r a c t i c e .
The h e a d mass m u s tb er e s t r a i n e df r o mf o r ea n da f tw h i p l a s h m o t i o n st h a tc a nb ed e v e l o p e d on t h e 7 c e r v i c a lv e r t e b r a e .
F a i l u r e t o r e s t r a i n t h e h e a dp e r m i t ss e v e r en e c ks t r a i n sa n d h e a dv e l o c i t yc o n d i t i o n st od e v e l o p .
T h eu p p e rt o r s om u s tb er e s t r a i n e dt op r e v e n tp i v o t i n gm o t i o n s a b o u t t h e p e l v i cr e g i o n s .T h em a j o r i t yo ft h eb o d y mass i s i n t h eu p p e rt o r s o ,c o n t a i n e di nt h eb o u n d a r y of t h e r i b c a g e a n dd o r s a lv e r t e b r a e ,w i t ht h ed o r s a lv e r t e b r a ea c t i n g as a t t a c h p o i n t sf o rt h er i b s .T h i ss e c t i o nt h e r e f o r ef o r m s a r e l a t i v e l y
r
r i g i ds t r u c t u r ef o rr e s t r a i n ts u p p o r t .M o v e m e n to ft h eu p p e r t o r s o i s t h e r e f o r e i n a r i g i df a s h i o na b o u tt h el u m b a rv e r t e b r a e a n d p e l v i c r e g i o n w h e n a l a pr e s t r a i n t i s e m p l o y e d . W i t h o u t u p p e r t o r s o r e s t r a i n t , t h e t o r s o momentum would t r a n s f e r t o t h ep e l v i cr e g i o n .
T h ep e l v i cr e g i o nm u s tb er e s t r a i n e dt oa v o i db e n d i n go ft h e l u m b a rv e r t e b r a ea n d t o p r e v e n tm o t i o no ft h ep e l v i ca n df o r e - l e g masses. T h el u m b a rv e r t e b r a ea n dt h el o w e rd o r s a lv e r t e b r a e r e c e i v ev e r y l i t t l e s u p p o r tf r o mt h er i bc a g es t r u c t u r e . V e r - t i c a l c o m p r e s s i v ea c c e l e r a t i o n so ft h eu p p e rb o d y a r e t h e r e f o r e a l m o s tw h o l e l ys u p p o r t e d b y t h i sv e r t e b r a ec o l u m ns e c t i o na n d c a nb ee x p e c t e dt oe x p e r i e n c em o r es e v e r e s t r e s s e s t h a nt h e u p p e rp o r t i o n so ft h eb a c kb o n es t r u c t u r e .R u p t u r e dd i s c s a r e f a i r l y common a n dm i g h tt h e r e f o r eo c c u rf r e q u e n t l yi nt h i s s e c t i o ni f i t i s n o tf i r m l ys u p p o r t e d .
T h es k e l e t a ls t r u c t u r e , a s s h o w n i n F i g u r e 4 , a n dt h ed i s t r i b u - t i o n o f masses a n dh i n g er e g i o n so ft h eb o d yi n d i c a t e a n e e d f o rb o d yr e s t r a i n t ,d u r i n gi m p a c t ,e x t e n d i n gf r o mt h ep e l v i s r e g i o nu p t o a n di n c l u d i n gt h eh e a d .T h er e l a t i v e masses o f t h e v a r i o u s b0d.y p a r t s a r e a p p r o x i m a t e d a s l i s t e di nF i g u r e 4 .
R e f e r e n c e 3 . 6 p o i n t so u tt h a ts h o u l d e rs t r a p sf a s t e n e d t o t h e l a pb e l tc a na p p l yf o r c e st h a tl i f ta n dr e d u c et h el a pb e l t e f f e c t i v e n e s s .
VELOCITY - DISTANCE - TIME
(SURVIVAL CRITERIA)
DECELERATION DISTANCE, (SI, To ZERO VELOCITY
(FEET) FIGURE I
RESTRAINED HUMAN I M M ENVEIBPE RESTRAINED HUMAN INJURY AREAS LIGHT AIRCRAFT CRASHES
FIGURE 3
r
SKELETAL STRUCTURE
NOMENCLATURE
VERTEBRAE
VERTEBRAE 5 '"""")2++
BODY PERCENT 100.0
FIGURE 4
AIRCRAFT EMERGENCY SURVIVAL . - METHODS Internal survival improvement methods in this report contain design objectives for occupant seating and restraint.' Other areas for improvement, such as fire supression, smoke and fume protection and evacuation aids are not elaborated in this study.
There tire a number of methods that could be applied in an aircraft emergency to protect the occupants from severe injury.
Only a few o f these methods can be applied at an acceptable price to the user. Figure 5 s'hows some of the methods that might be applied to assist survival in aircraft emergencies.
These methods are presented in chart form. The kind of methods that could be applied are divided into three basic modes o f flight: take-off, in-flight, and landing. The methods are further divided into applications to general aviation and commercial aviation, and executive aircraft. Those methods that appear reasonable to apply in a given flight mode and a particular type of aircraft are indicated by a solid dot.
AIRCRAFT EMERGENCY METHODS
C = COMMERCIAL AIR CARRIER
E = EXECUTIVE OFFICIALS
G = GENERAL AVI ATtON
FIGURE 5
1 2
I
~~~ INTERNAL -~ FUSELAGE IMPROVEMENTS Efforts to improve aircraft interiors are a result of accidents wherein the aircraft cabin has remained adequately intact for human survival but the occupants have, nevertheless, died or were seriously injured because of fumes, fire, inadequate seat tie-down/seat belt restraint, or impact with local hard objects placed too close for crash safety. A summary of notes by J.J. Carroll and published reports by A. H. Hasbrook7, combined with that data obtained by the Flight Safety Foundation, Inc.
point out that the interior design considerations for crash survival should include crashworthiness features such as: (1) Secure seat tie-down and seat energy absorption properties.
(2) Secure occupant restraint.
(3) Removal of lethal objects and surfaces from the occupant-impact envelope.
(4) Secure attachment of interior furnishings.
( 5 ) Suppression of smoke and fire.
( 6 ) Quick routes for evacuation.
Much remains to be done toward defining quantitative values to meet these requirements. In this respect, aircraft manufacturers have pointed out the need for accident survival methods/criteria that is of definite argument based on clear evidence and of a quantitative nature for design and test.
Work at the civil Aeromedical Research Institude (CAR11 has been extensive in defining human body impact limits and injury.
levels. The CAR1 work, combined with the aircraft crash test data of the Flight Safety Foundation, I ~ c . ~ provides addi- tional views on how aircraft interiors may be designed to improve chances for occupant survival.
2.2 S. R. Mohler and J. J. Swearingen estimate that possibly one half of all fatalities occurring annually in survivable aircraft accidents could be prevented if aircraft design were to include conditions for human tissue protection during impact.
These authors ,further detail three principles for delethalization: (1) Eliminate and/or redesign cabin objects which can cause puncture wounds upon bodily impact.
(2) Design and install a seat-restraint system (seat belt and shoulder harness) which will securely a human body under brief transient fbrces hold as high I s 25 g.(Ref.3.6,1.1.4.3.1). Tolerance to impulsive loading under severe body restraint may be taken as: (Ref.
3 . 6 ) Longitudinal - 4 5 0.10 sec.
g for 2 5 0.20 sec.
g for Lateral - 2 0 g for 0.10 sec.
Vertical - (Eyeballsdown) 25 g for0.10sec.
(Eyeballs up) 15 g for 0.10 sec.
( 3 ) Design instrument panels and all other areas of likely body contact s o that upon impact the greatest amount of deformation and material rearrangement would occur in the structures and not in the human body.
Occupant Protection & Interior Design Methods Improvements for the occupant in the aircraft interior are effective under flight conditions where the aircraft is i n a velocity and attitude condition that would allow impact to occur without severe destruction of the fuselage. Granting such impact conditions, the interior improvements are concerned primarily with occupant protection; thus, the removal of dangerous furnishings, sharp o r hard surfaces and loose objects that might impact with the occupant is compatible design for aircraft emergencies.
Occupant seating and restraint represents a major area of interior design that. could be improved with immediate benefits for occupant protection. F o r emergencies, full body restraint is essential to keep the occupant from flailing and impacting with surrounding hardware. In large passenger aircraft, seat and restraint design improvements are most essential to meet take-off and landing emergencies. Certain types of aircraft that undergo severe jostling conditions in-flight would a l s o be made more comfortable with a full body restraint system on the pilot.
Where an aircraft undergoes crash type conditions, the occupant protection can be improved by designing seats to absorb high energy pulses. Force limiting energy absorbing devices (Ref.
3.5) would reduce high peak forces and allow the seat to remain attached to the basic aircraft structure and maintain the occupant position i n the seat at lower f.orce levels. Such seat design would be immediately useful to all aircraft types. At the present time seats are not designed to absorb high energy impacts and therefore frequently come loose from the airframe structure.
Another form of protection for the occupant would be crash 1 4 c a p s u l e s . T h e n a t u r e o f c r a s h c a p s u l e s w o u l d r e q u i r e t h e m t ob es p e c i a ls t r u c t u r e sw i t h i nt h ea i r f r a m ed e s i g n e dt o r e s i s t a n da b s o r bi m p a c t a t h i g h e re n e r g yl e v e l st h a nt h ea i r c r a f t i t s e l f .S u c hd e v i c e sd on o ta p p e a re c o n o m i c a l l yp r a c t i c a lf o r m o s ta i r c r a f t ;h o w e v e r ,c r a s hc a p s u l e s m a y b eu s e f u lf o r s p e c i a le x e c u t i v ea p p l i c a t i o nw h e r e i n a maximum p r o t e c t i v e s e c u r i t y i s m o r ee s s e n t i a lt h a nt h eu s u a le c o n o m i cc o n s i d e r a - t i o n s f o r t h e a i r c r a f t .
Seat D e s i g n T h ei n t e g r a lp a r t so f a p a s s e n g e r s e a t s y s t e m a t t h ep r e s e n t t i m e a r e t h er e s t r a i n tb e l t ,b e l ta n c h o r a g e , s e a t p o r t i o n s w h i c h c a r r y b e l tl o a d s ,c u s h i o ns u p p o r ta n d s e a t a n c h o r a g e s t ot h ef l o o rs t r u c t u r e .I m p r o v e m e n t i s n e e d e d i n t h e d e s i g n o ft h e s ec o m p o n e n t s .
T h eu s eo fd u c t i l es t r u c t u r e s i s d e s i r a b l es i n c et h i sw o u l da l l o w d e f o r m a t i o n sa n da t t e n u a t i o np r e c l u d i n gc o m p l e t es e a tf a i l u r e .
W h e n e v e rp r a c t i c a l ,p a s s e n g e r s e a t s s h o u l do n l yb ea t t a c h e d t o a s u r f a c eo f .s t r u c t u r a lc o n t i n u i t y ,s u c h a s t h ec a b i nf l o o r .
A t t a c h m e n t st od i f f e r i n gs t r u c t u r es u r f a c e s ,s u c h a s w a l l - f l o o r c o m b i n a t i o ns t r u c t u r e ,c a nd e f o r md i f f e r e n t l yt oi m p o s es e v e r e t o r s i o no nt h e s e a t t i e s , r e s u l t i n gi ng r e a t e r s e a t t i e d o w n s t r e s s e s a n d d e f o r m a t i o n d a m a g e .
A i r c r a f t s e a t d e s i g n p r o v i d e s o n e i m m e d i a t e i m p r o v e m e n t a v e n u e f o r o c c u p a n t s a f e t y . S e a t s m a y b e i m p r o v e d b y g i v i n g d e s i g n a t t e n t i o nt ot h ef o l l o w i n g i t e m s : M i n i m i z e s e a t mass, p a r t i c u l a r l yi nt h eu p p e rp a r t so f t h e s e a t b a c kt or e d u c ei m p a c ta c c e l e r a t i o nm o m e n t . f o r c e s .
A v o i dt h ee x p o s u r eo fh a r ds t r u c t u r e sw h e r eb o d yi m p a c t m a y o c c u r .
U s e d u c t i l e ,e n e r g ya b s o r b i n g m a t e r i a l s f o rp r i m a r y s e a t s t r u c t u r e .
P r o v i d ee x o - s k e l e t a l s e a t s t r u c t u r ef o ro c c u p a n tp r o t e c t i o n .
P r o v i d e c r u s h a b l e i m p a c t a t t e n u a t i n g s u r f a c e s .
I n c r e a s ef l o o ra t t a c h m e n tj o i n tf l e x i b i l i t yt or e d u c eb e n d - i n g s t r e s s e s .
B u i l di n s e a t s a f e t ya i d sa g a i n s ts m o k e ,f u m e s , h e a t , v i s i o na n dd e c o m p r e s s i o n .
E x t e n du p p e r s e a t b a c ka b o v et h eh e a dl e v e lf o rh e a d p r o t e c t i o n .
1 5 R e s t r a i n t D e s i g n When a na i r c r a f tc o c k p i t o r c a b i n a r e a r e m a i n s r e l a t i v e l y i n t a c t a f t e r a c r a s hi m p a c t ,d e f i n i t ei m p r o v e m e n t sw o u l db e - r e a l i z e d i ft h ep a s s e n g e r o r c r e w m e m b e r were m o r ea d e q u a t e l yr e s t r a i n e d .
R e s t r a i n td e s i g n i s a ni n t e g r a lp a r to ft h e s e a t s y s t e m a n d n e e d sd e s i g ne f f o r tt o : ( 1 ) I m p r o v e b e l t l a t c h r e s i s t a n c e a g a i n s t a c c i d e n t a l r e l e a s e . F o r i n s t a n c e , s o m e b d l t l a t c h e s a r e s u s c e p t i b l et oa c c i d e n t a l r e l e a s e .
( 2 ) P r o v i d er e s t r a i n td e v i c e s f o r u p p e rt o r s oa n dh e a d i ns e v e r ee m e r g e n c i e s .
H e a di n j u r i e st a k e a h e a v yt o l le i t h e rd , i r e c t l y b yp u n c t u r e w o u n d s o r i n d i r e c t l y by s t u n n i n g b l o w s . T h e s e i n j u r i e s p r e - v e n tr a p i do c c u p a n t e x i t b e f o r ef i r ec o n s u m e st h ea i r c r a f t .
H e a da n ds h o u l d e rr e s t r a i n t i s t h e r e f o r ee s s e n t i a lt op r e v e n t e x c e s s i v eh e a dt r a v e la n dt op r o v i d e a d e g r e eo fs a f e t yt o many who a r e a t p r e s e n tk i l l e d o r who s u f f e rs e v e r ei n j u r i e s t oh e a d o r f a c e .
D e c e l e r a t i o n t e s t s h a v ed e m o n s t r a t e dt h a tw h e n a man i s w e l l r e s t r a i n e db y s e a t a n ds h o u l d e rh a r n e s s e s ,a n di ng o o dc o n d i t i o n h ec a nt o l e r a t ec r a s hf o r c ep e a k sf r o m1 5t o4 5g ' s( r e f . 3 . 6 ) .
T h i ss u b s t a n t i a t e st h eb e l i e ft h a tp e o p l es h o u l ds u r v i v ei m p a c t s w h e r et h es t r u c t u r e sr e m a i np r i m a r i l yi n t a c ts i n c et h e s es t r u c - a t m u c h l o w e r g - f o r c e s .
t u r e s f a i l 1 6 - COMMERCIAL ~ - - - - MULTI-ENGINE ~~ TRANSPORT SAFETY IMPROVEMENT Genera1 ~- ~~ Statistical Information
A commercial air carrier is an operator who has been issued a
Certificate of Public Convenience and Necessity by the CAB.
The two main categories of air carriers are the Certificated Route Carriers and the Supplemental Carriers.
Figure 6 is a bar graph that shows each major type and number of aircraft in operation by the certificated route air carriers as of December, 1965. Boeing, Douglas, Lockheed and Convair Corporations provide the greatest majority of the currently
of the 2104 fixed wing aircraft
used commercial aircraft.
listed as held by the air carriers, only about 1875 are actu- ally used for passenger operations. The number of commercial aircraft in active service (Figure 8 1 has only varied about 24% since 1957. The service provided by these aircraft is shown in Figure 7 as accumulated by all the aircraft, and again in Figure 8 as an annual average allotted to each aircraft.
Currently, the average transport aircraft travels 700,000 miles flies 2100 hours and makes 2200 departures per year.* The annual number of commercial carrier accidents is small when compared to the large number of aircraft operations during that period. Figure 9 shows an average of about 80 accidents to occur annually, out of the four million flight depatures.
Taking into account the total number o f accidents that occur annually, Figure 10 shows about one accident to occur per 50,000 departures, and coincidently, about one accident'to occur per every 5 0 , 0 0 0 flight hours. This averages about 11,000 departures or flight hours per day, so that some kind of aircraft accident might be expected to occur every five days.
systems is difficult to The reliability of aircraft transport numerous operating variables.
express in a simple manner because of *The statistics found in this section were derived from the "FAA Statistical Handbook of Aviation" and from the civil Aeronautics Board Annual "Statistical Review" and have been interpreted by the authors for presentation in this report.
Using the conglomerate of overall departure and flight time statistics and assuming all events to be equally probable, the reliability of the operating aircraft transport system could be expressed as: (1) Reliability 0.99998 that any one departure will be accident free, or perhaps (2) Reliability 0.99998 that any one hour of operation will be accident free.
This represents extremely good system reliability; however, it is a grossly simple interpretation and does not represent effects of individual case factors of time, distance, depart- ures, maintenance, weather, etc. While the accident rate is extremely small, the massive quantities of air carrier operations still inevitably result in a significant total number of accidents and fatalities as shown in Figure 11.
There were 1642 fatalities in commercial aviation during the period from 1960 through 1964 as a result of 64 fatal accidents.
These fatalities were distributed in categories as shown in Figure 12 and are summarized by Table 1.
TABLE 1 Percent of Percent of all Percent of all all accidents fatal accidents fatalities Take-off and 1 4 20 25 Initial Climb Enroute 26 45 60 Approach and 5 0 30 15 Landing 1 8 AIRCRAFT IN OPERATION B Y CERTIFICATED ROUTE AIR CARRIERS DEC. 1965 AIR
-
T U R B O J E T BOEING 707 BOEING 720 CONVAIR 990 CONVAIR 880 DC-8 BOEING 727 BAC-111 CARAVELLE. DC-9
I I I I I I
TURBOPROP
I I I
LOCKHEED- 188,188A I I VICKERSVISCOUNT
i
AR COS Y CANADAIR C L - 4 4 CONVAIR - 340T FAIRCHILD F-27 NO-262
t I I I I I I
PISTON ENGINE
DOUGLAS DC-4 L I I I I I I
DOUGLAS DC-6 DOUGLASDC-7 LOCKHEED-049/ 149 LOCKHEED-749 LOCKHEED-1 049 LOCKHEED- 1649 CONVAIR -240
C I I I I I
- 340 1440 CONVAIR C-46,ZOT DOUGLASDC-393A GRUMMAN G-21921A GRUMMAN G-44A MARTIN-LOZA
E t l l I I I
MARTIN-404
0 40 eo I20
NUMBER OF AIRCRAFT
FIGURE 6
CERTIFICATED ROUTE AIR CARRIERS
ALL SCHEDULED SERVlCE
I 954 1956 1958 1960 1962 1964 YEAR
FIGURE 7
CERTIFICATED PASSENGER /CARGO
U.S. DOMESTIC 81 INTERNATIONAL AIR CARRIERS
OPERATIONS DATA
(REF. 1966 FAA STATISTIC HANDBOOK) 700,000 FLKiHT-LnES PER AIRCRAFT 600,000
500.000 I
DEPARTURES FLIGHT- HOURS '4
, /'\
FLIGHT- HOURS N . ..
\ PER AIRCRAFT (AVERAGE ) 2ooo I800 NUMBER OF ARCRWT /* .-.
1 9 s 1958 1960 I962 I 9 6 4 1966
YEAR
FIGURE 8
U.S. CERTIFIED ROUTE AIR CARRIERS
ALL OPERATIONS- MJMBER OF ACCIDENTS BAR GRAPH KEY : . . . .. . . .
- . . . . . .
TOTAL ACCIDENTS 1 MINOR 01 NO INJURY ////A% SERIOUS INJURY NUMBER '*OT B FATAL INJURY 0 SUBSTANTIAL A/C DAMAGE 0 AIRCRAFT DESTROYED YEAR
FIGURE ,9
2 2
CERTIFICATED MSSENGERKARGO
U.S. DOMESTIC 8 INTERNATIONAL AIR CARRIERS
ACCIDENT RATE DATA
MCUYULATED ,O?
RIGHT-MILES BETMEN ACCIDENTS
t
+
I O f
ACCUMULATED DEPARTURES a FLIGHT-HOURS BETWEEN ACCIDENTS (AVERAGE) 40000 35000
IN- SERVCE 301
AIRCRAFT TO ACCIDENT RATIO I O f 1 1 I 1958 1 9 60 1962 1964 1 9 6 6
YEAR
FIGURE IO
U. S. AIR CARRl ERS
A L L OPERATIONS
FATALITIES PER FATAL ACCIDENT
I960 -1965
INCLUSIVE
‘40)
I20 I -SIX YEAR AVERAGE FATAL XUDENTS 1960-1964
FIGURE I I
U.S. AIR CARRER ACCIDENTS
1960 - I964 INCLUSIVE
402 ACClwNTS 64 FATAL ACCIDENTS I w 2 FATAUTES I
(P
I4 I 2 20 2 10.0
t t
56 12 21.4 404 INITIAL CLIMB
I
..
ENROUTE CRUISE 14.5 1 0 6 2 9 2'1.36 972
.,I CRUISE
~~ APPROACH
u
I LEVEL I
2 0 9.0 204 262
IrnL-OYT I
I OTHER 6.0 U N K N W l 2 . 5 0 0
I
.- ~ 402 1 0 0 % 64 TOTALS
FIGURE
1 2
T r a n s p o r t A i r c r a f t S e a t i n P - & R e s t r a i n t System-Impyo-pement .~ ".
T h en u m b e ro ft r a n s p o r ta i r c r a f te m e r g e n c i e s i s e v i d e n tf r o m t h es t a t i s t i c so fT a b l e 1, F i g u r e 11 a n d F i g u r e 12, T h e m u l t i - e n g i n er e c i p r o c a t i n ga n dt h e j e t e n g i n ea i r c r a f t a r e u s e d p r i m a r i l yb yc o m m e r c i a lc e r t i f i c a t e d a i r c a r r i e r sa n do f t e n c a r r yo v e r a h u n d r e d p a s s e n g e r s e a c h . T h e p r o b l e m o f i m p r o v i n g s u r v i v a li nt h i s c l a s s o fa i r c r a f t i s q u i t ed i f f e r e n tf r o m t h a ta s s o c i a t e dw i t hg e n e r a la v i a t i o n , P a s s e n g e r so na n yo n et r a n s p o r tf l i g h t m a y r e p r e s e n tt h ew h o l e s p e c t r u mo ft h ep o p u l a t i o ni na g e ,h e a l t h ,s i z ea n do c c u p a t i o n .
A l a r g en u m b e ro fp e r s o n ss e a t e di nr o wf a s h i o n i s a l s o a c h a r a c t e r i s t i co fp a s s e n g e rt r a n s p o r t st h a tn e c e s s i t a t e st h a t t h ep a s s e n g e rr e m a i ns e a t e da n db ep r o t e c t e di nt h a tp o s i t i o n u n t i ls u c h t i m e t h a t t h e a i r c r a f t h a s come t o a s t o pa n do r d e r l y e v a c u a t i o nc a nb e g i n .
O n eo ft h em o s td i f f i c u l tp r o b l e m sc o n f r o n t i n gd e s i g n e r sf o r i m p r o v e dp r o t e c t i o no fo c c u p a n t s i s t h ef a c tt h a to c c u p a n t s v a r yo v e rs u c h a l a r g er a n g e .T h em e t h o d su s e dt oi m p r o v e human s u r v i v a ld u r i n gt r a n s p o r te m e r g e n c i e sm u s tt h e r e f o r eb e c o m p a t i b l e w i t h a l l p e r s o n s . T h e i m p r o v e m e n t o f p a s s e n g e r s e a t d e s i g na n dr e s t r a i n tm u s tt a k et h ew i d ev a r i a t i o no f o c c u p a n t s i n t o a c c o u n t . T h e t e c h n i q u e s f o r e n e r g y a b s o r p t i o n a n dr e s t r a i n t a r e t h e r e b yc o m p l i c a t e d .
T h es k e l e t o ns h o w ni nF i g u r e 4 r e p r e s e n t st h es t r u c t u r eo fa n a v e r a g ea d u l t a s h em i g h tb es e a t e di n a p a s s e n g e ra i r c r a f t .
T h el o c a t i o n sa n dr e l a t i v e masses a r e a l s o s h o w nf o re a c hm a j o r b o d y s e g m e n t . T h e b o d y mass s e g m e n t d a t a i s d e r i v e di np a r t f r o m a s t u d y o n b o d y s e g m e n t p a r a m e t e r s . L o o k i n g a t t h e b o d y as a n o n - r i g i dp h y s i c a ls t r u c t u r ew i t h mass c e n t e r sa n df l e x i b l e j o i n t s , i t i s a p p a r e n tt h a tb o t hu p p e ra n dl o w e rt o r s or e s t r a i n t i s r e q u i r e dt op r e v e n ts p i n eb e n d i n ga n dh e a d - f l a i l i n gm o t i o n s t h a tc o u l dc a u s es e r i o u si n j u r i e s .T h er a p i dm o t i o no ft h eh e a d mass o nt h en e c kv e r t e b r a es t r u c t u r ea n dt h es t r a i nd e v e l o p e d by s u d d e n l ys t o p p i n gt h i s mass e v e nw i t h o u ti m p a c t i s t h ec a u s e o f m a n y n e c k i n j u r i e s . S i m i l a r l y , a c c e l e r a t i o n f o r c e s a c t i n g t ob e n dt h es p i n a lc o l u m ni m p o s es e v e r ec o m p r e s s i o na n d / o r t e n s i o n s t r e s s e s o nt h ev e r t e b r a ed i c s t r u c t u r ec a u s i n gs l i p p e d d i s c a n d o t h e r f o r m s o f b a c k i n j u r y . Some f o r mo fr e s t r a i n t i s r e q u i r e dt op r e v e n tt h e s eb o d yd i s p l a c e m e n t s ,s i n c em u s c l e r e s p o n s ea n ds t r e n g t ha l o n e i s i n a d e q u a t et or e a c tt os u d d e n i m p a c tf o r c e s .
T e s t s i n d i c a t et h a ti ns o m es u r v i v a b l ec r a s h e st h el o c a l d y n a m i cl o a d s m a y r e a c h 40 t o 5 0 g ' s f o rs h o r td u r a t i o n s , m e a s u r e di nm i l l i s e c o n d s . 3.6 I f t h e s e a t s a r e u n a b l e t o a b s o r bt h i ss u d d e ni m p u l s et h e y w i l l b r e a kl o o s e .
The maximum f o r c e sd e v e l o p e do n s e a t s t r u c t u r e a r e a r e s u l t o fr e l a t i v ev e l o c i t y mass a c c e l e r a t i o n sa n df l o o rs t r u c t u r a l d e f o r m a t i o n s . T h e s e d e v e l o p u n d e r c o n d i t i o n s o f a i r c r a f t r u n w a yo v e r s h o o t , or i m p a c tu n d e ra d v e r s ea t t i t u d e si nw h i c h t h ef u s e l a g e m e e t s s u d d e nr e s i s t a n c ea n du n d e r g o e ss t r u c t u r a l f a i l u r e .
T h eo c c u p a n th e l ds e a t e di nt h ea i r c r a f tc a ne x p e r i e n c eh i g h a c c e l e r a t i o n s i f h e d e v e l o p s i n d e p e n d e n t v e l o c i t y c h a n g e s o v e r a v e r ys h o r td i s t a n c e .E l a s t i c i t yo ft h ef u s e l a g es t r u c t u r e a n df r e eu n r e s t r a i n e dm o t i o n so ft h eo c c u p a n ta l l o wr e l a t i v e v e l o c i t yt ob u i l du pb e t w e e nt h e s e a t s a n dv a r i o u sp a r t so ft h e a i r c r a f t . I t i s i nt h ea r r e s t i n go ft h e s er e l a t i v ei n t e r . n a 1 v e l o c i t i e st h a ts u c hs h o r td u r a t i o n ,h i g hg - l e v e lf o r c e d ( 4 0 - 5 0 g ' s ) m a y d e v e l o pi nt h e s e a t s t r u c t u r e .
T h e r e a r e t w op r a c t i c ' a lr e q u i r e m e n t st h a tm u s tb e m e t f o ri m p r o v e d o c c u p a n t p r o t e c t i o n . O n e i s t h a tt h eo c c u p a n t ' sv i t a lp a r t s m u s tb ek e p tf r o mb u i l d i n gu pd i f f e r e n t i a lv e l o c i t i e si ne x c e s s o f a b o u t 30 o r 4 0 f e e t p e r s e c o n d . I n a d d i t i o n , t h e s e d i f f e r - e n t i a lv e l o c i t i e sm u s tb es t o p p e dw i t h i n a s p a c eo fa b o u t 6-8 i n c h e st op r e v e n te x c e s s i v ea c c e l e r a t i o nl o a d so nt h eo c c u p a n t .
S e c o n d l y ,t h eb o d yl o a d sm u s tb et r a n s f e r r e di n t ot h e s e a t by a r e s t r a i n ta n dc u s h i o ns u p p o r ts y s t e mt h a td o e sn o th a v e s i g n i f i c a n tr e b o u n d .
T h e s e a t m a y b et h o u g h t of a s b e i n gc o m p o s e do ft h r e eb a s i cp a r t s .
T h o s e p a r t s a r e : t h e l e g s , w h i c h s h o u l d b e e n e r g , y a b s o r b i n g i no r d e rt ot r a n s f e rl a r g eq u a n t i t i e so fe n e r g yw i t h o u td e v e l o p - i n gh i g hp e a kl o a d s ; a s u p p o r t i n gf r a m ew i t hc u s h i o n sw h i c hw o u l d a c tt op r o t e c tt h eo c c u p a n t ;a n dt h i r d l y , s o m e f o r m o f b o d y r e s - t r a i n tw h i c h i s a b l et om a i n t a i nt h eo c c u p a n ti np o s i t i o nr e g a r d - l e s s o fh i ss i z e o r s h a p e .
S e a t s t h a t a r e s u i t a b l ef o rp r o v i d i n g a l a r g ea m o u n to fe n e r g y a b s o r p t i o na n do c c u p a n tp r o t e c t i o ns h o u l db em o u n t e d as s i n g l e u n i t s ; t h a t i s , t h e ys h o u l dn o tb es t r u c t u r a l l yt i e di n t op a i r s a n dt r i p l e t s as a ni n t e g r a lu n i t as c u r r e n t l yp r a c t i c e di n p a s s e n g e ra i r c r a f t .T h i s i s n o tt o s a y t h a ti n d i v i d u a le n e r g y a b s o r b i n g s e a t d e s i g n sc o u l d n ' tb eg . r o u p e di nc l o s ed o u b l e t a n dt r i p l e tt y p ea r r a n g e m e n t s ,b u tr a t h e rt h a tt h e s e s e a t s w o u l d have to have the capability o f moving independently of one another under impact situations to avoid assymmetrical loading and to accomplish efficient energy absorption.
Features that could be incorporated in advance seat design are shown in Figure 1 3 entitled "Aircraft Seat Design Improvement for Impact". Some of the features pointed out in that figure are the high back protective head rests,the impact absorbing back structure, high energy dissipation cushions, high-energy dissipation stroking load limiting l e g s , and a full body res- traint system. This may be compared with present seat designs which use rigid leg structures, lap belt restraint only, low energy absorption cushions, soft back structures and no head protection.
The simple technique of using the available seat spacing for stroking energy devices increases seat leg energy dissipation by a factor of about 6 without increasing the basic seat design strength. Using present seat design techniques and increasing the seat design strength to about 25 g's would only increase the energy absorption capabilities of present seats by about 2 4 times. B y comparison, advanced energy absorption seat de- sign, when increased to 2 5 g design strength level, would increase the energy absorption capability by a factor of 16.
Such improvements are a result of allowing the seat to stroke in a controlled load limiting manner while absorbing energy throughout that stroke.
The ability to take advantage of an increased seat energy absorption capability lies in a full body restraint system that can transfer body loads into the seat in d simple prac- tical manner.
Energy Absorbing Seat Development One example of a light-weight, high-strength seat which is designed to offer maximum energy absorption is shown in Fig- urel8. Energy absorption is provided by extensible attenuators in forward and vertical loadings. This seat is designed for impact attenuation for the dynamic load conditions of 2 0 g-vert tical and 2 0 g forward within a 30 degree arc to either side, as well as for 10 g's laterally. This seat strength is based upon an occupant weight of 225 pounds.
2 8 I I -- Seat w e i g h t i s k e p t t o a m i n i m u mt h r o u g ht h eu s eo fa l u m i n u m h o n e y c o m b c o n s t r u c t i o n i n a l l s t r u c t u r a lp a n e l s . Less c u s h i o n s a n dm o u n t i n gt r a c k s ,t h e s e a t w e i g h t sa p p r o x i m a t e l y 35 p o u n d s .
I n t e g r a t e dS a f e t y Seat R e f e r r i n gt oF i g u r e 3 a , i t c a nb es e e nt h a t a p a s s e n g e r who i s r e s t r a i n e do n l yb y a s e a t b e l t i s t h r o w nf o r w a r df r o mt h e w a i s t u p .T h et o r s oa n dh e a ds w i n g st h r o u g ha na r cs u c ht h a t t h eh e a dw o u l di m p a c ti n t ot h ef r o n t s e a t o rp a n e lo b j e c t s .
T h el e g sa l s os w i n gs u c ht h a tt h e yw o u l di m p a c t s i m i l a r o b j e c t s .
F i g u r e1 5i l l u s t r a t e sa ni n t e g r a t e ds a f e t y s e a t c o n c e p ta n do n e m e t h o dw h e r e b yt h eb o d yc o u l db er e s t r a i n e df r o mt h e w a i s t t o t h eh e a d .T h er e s t r a i n tm e t h o du s e s a b o d yc u r t a i nw h i c h i s s t o r e do nt h et o po ft h e s e a t b a c kb e n e a t ht h eu p h o l s t e r y .
O r d i n a r i l y ,t h ec u r t a i n i s n o t u s e d ; h o w e v e r , i n a n e m e r g e n c y i t w o u l d b e a s i m p l e m a t t e r t or e a c ha b o v et h eh e a da n dp u l l t h ec u r t a i n down o v e rt h eb o d ya n df a s t e n i t t o t h e s e a t b e l t .
T h i sm e t h o do fb o d yr e s t r a i n th a st h ea d l r a n t a g eo fn o ti n t e r - f e r r i n gw i t ht h ep a s s e n g e rc o m f o r tu n l e s sa ne m e r g e n c yo c c u r s .
.The c u r t a i nw o u l db es u f f i c i e n t l yp o r o u sa n dr e s i l i e n tt op e r - m i t b o t hb r e a t h i n ga n df o r c ed i s t r i b u t i o n .I na d d i t i o nt ot h e f a c ec u r t a i n ,t h e s e a t s h o w ni nF i g u r e1 5f e a t u r e se n e r g y - a b s o r b - i n gl e gs u p p o r t sa n d a h i g h s e a t b a c ke x t e n d i n ga b o v et h eh e a d l e v e li no r d e rt op r o t e c tt h eh e a df r o mf l y i n go b j e c t s .
E n e r g ya b s o r b i n gs u p p o r t s a r e s u f f i c i e n t l yr i g i dt o r e s i s t n o r m a l p a s s e n g e rl o a d s ;h o w e v e r ,u n d e rt h e much h i g h e rf o r c e so f a c r a s h ,t h el e g sw o u l dd e f o r ma n da b s o r be n e r g yi nt h ep r o c e s s o f s e a ts t r o k i n g .F u r t h e rs t u d y i s r e q u i r e d o n t h i st y p eo f s e a t i n g ,b o t hf r o mt h es t a n d p o i n to fd e t a i ls t r u c t u r ea n df r o m t h es t a n d p o i n t o f a c c o m m o d a t i o n .
O t h e rf e a t u r e st h a tm i g h tb ec o n s i d e r e di nt h ed e s i g no f a s a f e t y s e a t t o meet p a s s e n g e rr e q u i r e m e n t si n c l u d es u c ht h i n g s as a i r s u p p l y ,f o o d t r a y s , r e a d y - t o - s e r v ef o o dp a c k a g e s ,t r a s hc o l l e c - t i o nu n i t s ,m i n o rf i r s t - a i dn e e d s ,s m o k e - h e a t - v i s i o np r o t e c t i v e d e v i c e s ,a n df l o a t a t i o ng e a r .
H o n e y c o m b D e s i g n f o r Impact S u r v i v a l A l u m i n u m h o n e y c o m b i s a ne f f e c t i v em e c h a n i c a le n e r g ya b s o r b e r a n d i s f i n d i n gi n c r e a s e du s ei nt h ec o n t r o lo ff o r c e st od e c e l - e r a t e o b j e c t s . l1 M a t e r i a l s s u c h as s p o n g e ,s o l i dr u b b e r ,c o r k , a n dp a p e rw a d d i n gg e n e r a l l ye x h i b i ts p r i n gc h a r a c t e r i s t i c sw i t h a n a t t e n d e n tr e b o u n dp r o b l e m .
Aluminum honeycomb has the unique property of failing at a con- stant load with complete dissipation o f energy that would otherwise be released in rebound. The initial peak at which compressive failure begins can be eliminated by pre-crimping the honeycomb core to produce slight initial compressive fail- ure. When exposed to further loading the pre-crimped core proceeds to carry the crushing load at a near linear rate.
Such control appears attractive in safeguarding human occupants in aircraft crash conditions.
As an example of aluminum honeycomb's ability to attenuate human impact loads, consider this representative case: Assuming the impacting mass to be the human head with a weight of about twelve (12) pounds and assuming that the occupant is restrained by a seat belt, the head could be expected to impact a forward surface (instrument panel, seat back, etc) at a vel- ocity of over 40 ft/sec. Under these conditions, approximately 320 ft-lb of kinetic energy would be dissipated at head impact Without a yielding material to absorb this energy, death is certain. However, rough calculations indicate that such an impact upon an aluminum honeycomb (3003 aluminum, 3/4 inch cell, and a . 0 0 4 inch foil gage112 section with a thickness somewhat over 3 inches could be tolerated by the human head.
Kinetic energy at impact = (11.5>(42>2 320 ft.-lb.
2g 64.4
The rate of deceleration is approximated by : A = v /2sc
It appears practical to pad areas of likely body contact in all types of aviation vehicles with honeycomb o r similar material to improve survival.
A I R C R A F T S E A T D E S I G N IMPROVEMENT FOR IMPACT no head protection head rest full body soft back high energy issipation cushions high energy cushions dissipation l e g s advanced seat (stroking) design technique
\
increased seat strength with present rigid design technique does not give muchimprovement SEAT D E S I G N o f impact capability
30 t
STRENGTH ( g ' s ) h lev ,els act c ap- , 0 2 4 6 8 10 12 14 16 ENERGY D I S S I P A T I O N IMPROVEMENT (multiple o f present seat design)
FIGURE 1 3
20-G ENERGY ABSORBING SEAT
EXTENSIBLE STEEL ROD Y l u D l N o ATTENWTOR BEFORE IMPACT AFTER IMPACT
FIGURE 14
3 2
SAFETY SEAT
~ _ _ _ INTEGRATED ~"
(ENERGY ABSORBING)
EMERoENc( Booy
/ CURTAIN
EXTENSIBLE STEEL ROD YIELDING A T T E N T U A m SEAT 1 . EOS HIOH BACU HEAD PROTECTION STRUCTURE SEAT W V E S FORWARD 8 DOWN SEAT BELT BEFORE IMPKT IMPACT
FIGURE 1 5
3 3 GENERAL AVIATION SAFETY IMPROVEMENT General Aviation Statistics U . S . General Aviation includes all domestic civil flying other than scheduled and related flying of public airlines. Over the past several years the annual flying time of general avia- tion has been about four times the flying time of domestic public air carriers.
General aviation flying is categorized by five types: pleasure, business, aerial application, instruction and commercial/miscell- aneous.
General aviation pleasure flying accounted for about 25% of the total flying hours and for one-half of the pilot fatalities in the 1962-63 period.
The second highest accident mortality rate is experienced in commercial air taxi service,fire contr31 activities, and miscellaneous flying. While the time spent in commercial fly- ing is nearly the same (25%) as in pleasure flying,the actual number of deaths was only about one-third that of pleasure flying.
Business flying has experienced a somewhat better accident record than commercial flying. Business flying utilizes air- craft to transport executives, sales personnel, etc., and accounts for roughly two-fifths of the total flying time in general aviation. In 1962-63 the fatality rate for business flying was 3.5 per 100,000 plane hours, or about 40 percent lower than for general aviation as a whole.
The instructional flying category consists of flight training of civilians under accredited instructor supervision. One- sixth of the total flying time was accounted for by instructional flying in 1962-63. However, this type of flying was responsible for only one-twentieth of all fatalities.
General aviation data presehted in this section are for all flying categories and for all types of aircraft and includes over 90,000 aircraft of all types. This is twice the number of only ten years ago and the rapid growth continues. Figure 16 graphically portrays this rapid growth.
3 4 A n n u a l l y ,o u to ft h eg e n e r a la v i a t i o na i r c r a f t ,a b o u to n ei n 18 c a nb ee x p e c t e dt oh a v ea na c c i d e n to fs o m et y p e ;o n e a i r - c r a f t i n 2 5 c a nb ee x p e c t e dt or e c e i v es u b s t a n t i a ld a m a g e ; o n ea i r c r a f ti n9 0c a nb ee x p e c t e dt ob ed e s t r o y e d ;a n da b o u t o n ea i r c r a f ti n1 8 0c a nb ee x p e c t e dt oi n c l u d ef a t a l i t i e s .
T h er e c o r do fg e n e r a la v i a t i o n( F i g u r e1 6 )s h o w st h a ta na c c i - d e n to c c u r sf o re v e r y 4000 h o u r so fa c c u m u l a t e df l y i n g t i m e w h i l et h ec o m m e r c i a l a i r c a r r i e r r e c o r da v e r a g e s 5 0 , 0 0 0 f l y i n gh o u r sb e t w e e na c c i d e n t s .
F i g u r e 1 7 s h o w st h en u m b e ro fa c c i d e n t sc u r r e n t l y a t 5000 p e r y e a r , o f w h i c h . 500 a r e f a t a l ,a n d1 0 0 0a i r c r a f t a r e d e s t r o y e d .
T h ea c t u a ln u m b e ro ff a t a l i t i e sh a si n c r e a s e dt oo v e r1 0 0 0 p e r y e a r i na p p a r e n tp r o p o r t i o nw i t ht h ei n c r e a s e dn u m b e ro f a i r c r a f t .T h er a p i du p w a r dt r e n d i s shown i nF i g u r e1 8 .
A b r e a k d o w no fg e n e r a la v i a t i o na c c i d e n t sb yp h a s eo fo p e r a t i o n f o r y e a r 1 9 6 3 i s s h o w n i n F i g u r e 1 9 . I t i s r e a d i l ya p p a r e n t t h a tt h el a r g e s ts i n g l ep e r c e n t a g eo fa c c i d e n t so c c u rd u r i n g l a n d i n g ;h o w e v e r ,o n l y a s m a l l number o f t h e s ee n dw i t hf a t a l i t i e s .
M o s to ft h ef a t a l i t i e so c c u rd u r i n gn o r m a lc r u i s e ,o ro t h e r i n - f l i g h tc o n d i t i o n sa s s o c i a t e dw i t hb a dw e a t h e r ,m a l f u n c t i o no f s y s t e m s , p i l o te r r o ro ru n e x p e c t e dc o l l i s i o n .
3 5
GENERAL AVIATION - A l L TYPES AIRCRAFT
A
85- 1 9
/I
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l8 AIRCRAFT 7 5 - + , , TOTAL NUMBER 1 6 of 4- AIRCRAFT 6 5 x 10s I # I I
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55 I 1 3
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50- 1 2 NUMBER OF AIRCRAFT
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I I 45-
4 0- I I I I I I I "H-L 3 1 9 6 5 1 0
1955 I S I& HOURS/FATAL ACCENTS Y € M TIME BETWEEN M C I D E M S
FIGURE 1 6
GENERAL AVlATlON
A U OPERATIONS- NUMBER OF ACCIDENTS BAR GRAPH KEY: .. . .....
. . .. . . ..
TOTAL ACCIDENTS 4"UNU MNOR t x NO INJURY
' / / m a S E R W INJURY
- FigTAL INJURY
OF ACCIDENTS : f .. 0 SUBSTANnAL A/C CNhUEE ..
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.. .. ;; 0 AIRCRAFT DESTROYED ..
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I958 I959 I960 1 9 6 1 1962 I963 1964 l 9 6 ! 5 1 9 6 6 YEAR
FIGURE 1 7
3 7
GENERAL AVIATION
ACCIDENT STATISTICS
FATALITIES e SERIOUS INJURES FATALITIES PER FATAL ACCIDENT 2 .o 1.8 I .6
A
450- SERIOUS INJURES V d o : : ! : : . : ! ! : . : : ! : . : : t 9 5 0 1956 1960 1965 YEAR
FIGURE 1 8
GENERAL AVIATION-ALL OPERATIONS
@oo ACTIVE A I R C R A F ~
TYPICAL DISTRIBUTION OF ACCIDENTS BY PHASE-YEAR 1963
-
LANDING RCLL OUT .TOUCH DOWN
-
JlNAl APPROACH
IN I TIA L APPROAf H
b P) DESCENDlNG ACROBATICS d W Z Z l ~ QTHFR (TN F L I G H ~ ~ NORUAL CRUlSF S L I M E TO CRUISE J N I TlAL A B O R T E D TAKE-OFF ;.ROUND- R l ' N - _.
TAXI TC TAKE CFF " _ ___ -"
P I
I " I
C 2 cc 4 00 coo 8 00 G I OG ZOG
TOTAL NUUBER OF ACCIDENTS TOTAL FATAL1TIES
FIGURE 1 9
INTERNAL IMPROVEMENTS Seat A t t a c h m e n t M a n u f a c t u r e r so fg e n e r a la v i a t i o na i r c r a f t a r e o b l i g e d t o o b s e r v e t h er e q u i r e m e n t so fF e d e r a l A i r R e g u l a t i o n s P a r t 2 3 , A i r w o r t h i - n e s s S t a n d a r d s : N o r m a l , U t i l i t y , a n d A c r o b a t i c C a t e g o r y Air- p l a n e s .U n d e rt h ed e s i g nr e q u i r e m e n t s~ p e c i f i e dh e r e i nt h e s e a t s t r u c t u r ew i t ha no c c u p a n tr e s t r a i n e d by b e l to rh a r n e s s s h o u l db ec a p a b l eo fu l t i m a t ef o r c e s as f o l l o w s : Upward 3 . 0 g ( 4 . 5 g A c r o b a t i c C a t e g o r y ) F o r w a r d 9 . 0 g S i d e w a r d 1 . 5 g T h e s ef o r c e l i m i t s a p p l yt om i n o rc r a s hc o n d i t i o n sa n dp r o v i d e a r e a s o n a b l ec h a n c eo fe s . c a p i n gs e r i o u si n j u r y ,b u tu n d e r c e r t a i nc o n d i t i o n s much h i g h e rp e a kg ' s m a y b ee x p e r i e n c e d .
S e a t s m a y b r e a kl o o s eu n d e rt h i sl o a d i n ga n dp o i n to u tt h e n e e df o ra ne n e r g ya b s o r b i n g s e a t a t t a c h m e n t .
T h en e e df o r f u l l b o d yr e s t r a . i n t i s a p p a r e n tf r o mF i g u r e 3 a n d f r o mF i g u r e 2 0 , w h i c hs h o w sg - f o r c ec u r v e so b t a i n e df r o mc a t a - p u l t i n ga ni n s t r u m e n t e d dummy h e a da g a i n s t a t y p i c a lu n p r o t e c t e d l i g h t a i r c r a f t i n s t r u m e n t p a n e l . As n o t e d , t h e l o w e s t i m p a c t v e l o c i t yp r o d u c e d a p e a k g v a l u e o f o v e r 1 6 0 g .T h er i g i dp a n e l d i dn o td e f o r m s o t h eh e a di m p a c t e dt h ep a n e lo v e r a v e r y s m a l l a r e a . T h e f o r e h e a d i s t h e s t r o n g e s t p a r t o f t h e f a c e , b u t i t c a n n o tw i t h s t a n d a f o r c eo f 8 0 g ' so no n es q u a r ei n c ho f a r e a w i t h o u t f r a c t u r e . T h e r e f o r e , a l l i n j u r i e sd e p i c t e di nF i g u r e 2 0 w o u l dc a u s ef a t a lh e a di n j u r i e s .
HEAD IMPACT ACCELERATIONS
G -FORCE CURVES OBTAINED WITH HEAD IMPACTS ON A TYPICAL LIGHT -
AIRCRAFT INSTRUMENT WNEL A T VELOCITIES OF (I) 17.6 FT / S E C , (2) 2,6.7 F T / SEC, AND (3) 42.2 FT / SEC.
z
- 1 2 0 -80 -40 4 8 12 16 4 8 I2 I6 20 T I M IN MILLISECONDS TIME IN MILLISECONDS REF. AM 66-12
FIGURE 20
HUMAN TOLERANCES T h i s s e c t i o np r e s e n t s a n u m b e ro fg r a p h i c a l d a t a r e l a t e d t o human t o l e r a n c e sf o ra c c e l e r a t i o n ,i m p a c t ,t e m p e r a t u r e ,a n d d e c o m p r e s s i o n . T h e s e d a t a were g a t h e r e d f r o m t h e NASA S P - 3 0 0 6 " B i o a s t r o n a u t i c s Data B o o k " a n d FAA r e p o r t s AM 6 6 - 1 2 ,a n d AM 6 6 - 1 8 w r i t t e nb y J. J. S w e a r i n g e n ,o f t h e c i v i lA e r o m e d i c a l R e s e a r c h I n s t i t u d e . T h e s e p a r t i c u l a r g r a p h s h a v e b e e n s e l e c t e d b e c a u s eo ft h e i rd i r e c tr e l a t i o n s h i pt oa i r c r a f ta c c i d e n ts u r - v i v a l .
The g r a p h si n t h i s s e c t i o n a r e p r o v i d e dm a i n l y a s s u p p l e m e n t a r y s u r v i v a lc r i t e r i a d a t a .
F i g u r e A-8 s h o w s t h e r e l a t i o n s h i po f maximum a c c e l e r a t i o na n d o n s e t r a t e f o rs t o p p i n gd i s t a n c e sf r o m 4 t o 8 i n c h e sf r o m a 30 f t / s e c .i m p a c tv e l o ~ i t y . ~ The m o s te f f i c i e n tu s eo fs t o p p i n g d i s t a n c e i s p r o d u c e d b y a n i n f i n i t e o n s e t r a t e . T h i s i s r e - p r e s e n t e d b y t h e minimum g ,i n f i n i t eo n s e tp o i n to fe a c hc u r v e .
A t r i a n g u l a r t i m e h i s t o r y i s r e p r e s e n t e db y t h e maximum g e n d p o i n t o f e a c h c u r v e . The p o i n t s b e t w e e n t h e s e t w o e x t r e m e s r e - p r e s e n tt r a p e z o i d a l t i m e h i s t o r i e s w i t h s p e c i f i co n s e t r a t e s a n d a f i n i t ec r u s h i n g t i m e a t c o n s t a n tg .F o rp r o t e c t i o no f h u m a n s ,t h e a r e a s o fh i g h g a n dl o wo n s e t r a t e a r e o f i n t e r e s t .
S u p e r i m p o s e do nt h i sf i g u r e a r e t h e a p p r o x i m a t ea c c e l e r a t i o n t o l e r a n c e s lo f o r humans w i t h a c c e l e r a t i o nd u r a t i o n t i m e l a b e l e d f o r e a c h d a t a p o i n t .
F o ri m p a c td u r a t i o n so f l e s s t h a n 0 . 0 7 s e c o n d s , i t i s a s s u m e d t h a t t h e b o d ya c t s as a r i g i d mass w i t hn of l u i ds h i f t so c c u r r i n g .
T h o m p s o na s s u m e dt h a ts t r u c t u r a l l i m i t s f o rb o d yt i s s u e a r e i ne x c e s s o f 2 0 0 g , a n dc o n s t r u c t e dt h et o l e r a n c ec u r v eo fF i g u r e A - 9 . T h e m a g n i t u d e o f p e a k g m a y r a n g eu pt o4 5 g f o ri m p a c t s o fg r e a t e rt h a n 0 . 0 7 s e c o n dd u r a t i o n ,h e n c et h e r e i s i n f i n i t e a r e a . F o r i m p a c t s o f s l o p ef o rt h et o l e r a n c ec u r v ei nt h i s l e s s d u r a t i o n t i m e , u pt oa b o u t 2 0 0 g , t h et o l e r a n c e limit i s
r e p r e s e n t e d b y th'e c r i t e r i a t h a t2 v = 1 0 0 (v= 5 0 f p s ) a n d
f o r t h i s a r e a t h e t o l e r a n c ec u r v e i s h o r i z o n t a l .T h ev a l i d i t y o ft h i sc o n c e p t i s i n d i c a t e d b y t h ed a t ap o i n t so nF i g u r e A - 9 .
B a s e d o n t h e s e t e s t r e s u l t s ,a n ds h o w ni nF i g u r e A - l o , A . B .
Thompson s t a t e s t h a t t h e u l t i m a t e human l i m i t s t o e n t i r e b o d y i m p a c t ' i ss o m e w h e r ei nt h er a n g eo f 4 5 a n d5 5p s ii m p a c tf o r c e .
T h ep h y s i o l o g i c a ls h o c ky i e l dp o i n t l i e s s o m e w h e r e b e t w e e n 2 8 a n d3 2p s if o rt r a n s v e r s ea c c e l e r a t i o n s .
4 2
ACCELERATION TOLEKANCE
Time REF. NASA SP- 3006
t o grayout
A*
. - l o 20 70 So 8 0 loo 200 300 joo AVERAGE ACCELERATION - Gunits a I 2 3 4 5 6 7 RATE OF ONSET OF ACCELERATION G/wc C .
vrloci t y t t/sec D E C E L E R A T I O N-DISTANCE ( w d REF, NA-SA SP-3006
FIGURE A - I
4 3
: : : : : : : : SEV E RE I N J U RY
- L I U t T S UPON WHICH CURRENT EJECTIGN SEATS ARE DSGN.
AREA OF VOLUNTARY HUMAN EXPOSURES@NINJURED) UNIFORM ACCELERATION OF VEHICLE @ units) .-\ .OOL.OO~ ,005 01 .02 m .os .I .a - 3 I 2 3 c LQ 20 34 sa \a0 DURATION OF UNIFORM ACCELERATION - seconds REF. NASA SP-3006
FIGURE A-2
I
ABRUPT TRANSVE-RSE DECELERF.TIONS
UNIFORM ACCELERATION OF VEHICLE
6 units)
A.
" ..
DURATION OF UNIFORM ACCELERATION - second; 75555 SEVERE INJURY AREA OF UNINJURED UNIFORM ACCELERATION OF VEHICL @ u n i t 3 B .
WRATION OF UNIFORM ACCELERATION-seconds REF; N A S A SP-3006
FIGURE A - 3
4 5 Ref. J. J . Swearingen AM-66-16 CIVIL AEROMEDICAL RESEARCH INSTITUTE Office of Aviation Medicine F e d e r a l A v i a t i a A g e n c y
FIGURE A- 4
4 6
HUMAN TOLERANCE TO TEMPERATURE
REF. NASA SP-3006 I MIN I HI? 6HR5 I DAY I MG I YR TEMP.
w
4cc IO0 -100 T I M E - S E C .
FIGURE A - 5
DECOMPRESSION DATA
VOLUMETRIC FLOW - TIME CONSTANTS CAB1 N VOLUME FT FFFCCTlVt AREA OF ORIFICE . i i 2 CONSCIOUSNESS OVER PRESSURE TOLERANCE I 2 4 6 # I O 10 W b O 1 0 0 240 WbW WOO Pulse duration-msec 0 Y) '20 U, lp CO b* 70 go W 100 Time of u s e f u l consciousness-sec.
RLF. NASA SP-3006
FIGURE A - 6
MECHANICAL EFFECTS O F HIGH DYNAMIC PRESSURES
A
f
I
FIGURE A - 7
01 E Y E BALLS O U T TOLE R A N C E ? I I N h , I OUT INJURY E l , I 0 I N V a r i a t i c n o f r r a x i m u m a c c e l e r a t i o n a n d o n s e t r a t e f o r c c n s t a n t values o f s t c p p i n s d i s t a n c e f c r a n i m p a c ' tv e l o c i t y c f 30 f t / s e c - REF. NASA TECH.NOTE 0-158
FIGURE A - 8
5 0 .
". ,.. -.....
, . ...
. . . .
5 2
&
7 0
s
I a N I Human
/' I
I structural S a f e z o n e limit zone I I 2 0 I G - Peak -Human T r a r s v e r s e Impact Tolerance, 2 A V Versus Peak G REF- ASD-TDR-63-173
FIGURE A-9
7 0 5 c 4c 2c IC 0.005 0.01 0.02 0.05 0.1 0.2 0 . 5 I .07 Time (5cc) Human T r d n s v e r s e I m p a c t Tolerance a s D e f i n e d by U n i t Impact Pressure andTime REF. ASD - T D R - 6 3 4 7 3
FIGURE A - IO
5 2 REFERENCES 1. "Safety Considerations for Passengers and Crew" By: James E.
Dougherty and Richard B. Stophlet, Federal Av.iation Agency,
Washington, D.C.; A I M Third Annual Meeting; Boston, Massachu-
setts, November 1966; A I M Paper Number 66-844 2 . Civil Aeromedical Research Institute, Oklahoma City, Oklahoma Federal Aviation Agency, Office of Aviation Medicine 2.1 Swearingen, John J.
"Tolerances of the Human Face to Crash Impact" AM 65-20, July 1965 2.2Mohler, S.R. AndSwearingen,J.J.
"Cockpit Design for Impact Survival" AM 66-3, February 1966 2.3Swearingen, J . J . , Hasbrook,A.H.,Snyder, R.G.
"Kinematic Behavior of the Human Body During Deceleration" AM 62-13, June 1962 2.4 Swearingen, J.J.
"Injury Potentials of Light Aircraft Instrument Panels" AM 66-12, April 1966 2.5 DeHaven, H.
"The Site, Frequency and Dangerousness of Injury Sus- tained by 800 Survivors o f Light Plane Accidents" Department of Public Health and Preventative Medicine, Cornel1 University, Medical College, July 1952 3. Flight Safety Foundation, Inc., Phoenix, Arizona 3.1 "Fu11 Scale Dynamic Crash Test of a Lockheed Constellation
Model 1649 Aircraft.1 - Technical Report
RPT. FAA-ADS-38 October 1965 B y : Flight Safety Foundation Contract No. FA-WA-4569 FAA Aircraft Development Service 3.2 "Fu11 Scale Dynamic Crash Test of a Douglas DC-7 Aircraft" Technical Report
RPT. FAA-ADS-37 April 1965
5 3 References - Cdntinued: 3. 3.3TrecomTechnicalReport66-77,January 1964 Experimental Research "CH-21A Helicopter Airframe Deformation Under a Dynamic Crash Condition" U.S. Army Transportation Research Command Ft. Eustis, Virginia By: Flight Safety Foundation; W.H. R e e d , D. F.
Carroll; Contract DA 44-177-AMC-888(T) J.L. Reed, Project Engineer Lt. col. T. C. Woodbury Johnson, Group Leader Larry M. Hewin, Technical Director 3.4 "Floor Accelerations and Passenger Injuries in Trans- port Aircraft Accidents" AV-Ser 66-19; Haley, Turnbow and Walhout. USAAVLABS TR67-16.
3.5"AircraftPassenger-Seat-SystemResponsetoImpulsive Loads" AV-Ser 66-20; Turnbow, Collins, Cromock & Mylclestal, USAAVLABS TR 67-17.
3.6 "Crash Survival Design Guide" AV-Ser USAAVLABS TR-67-22, Turnbow, et. al.
3.7 "Body Segment Parameters" New Y o r k University School of Engineering & Science TR #1166.03, by Drillis & Contini 4. Consolidated Notes on Aircraft Safety, J.J. Carroll; bnpublished). FAA Headquarters,Washington, D . C .
5 . "Bioastronautics Data Book", NASA SP-3006
6. Seribner, Kimball J . , Captain,Pan American Airways
"Emergency Barriers for Transport Aircraft" Space and Flight Equipment Association Third National Flight Safety Survival and Personnel Equipment Symposium, October 1965 7. Design of Passenger "Tie-Down'*, Sept. 1965, CSDM #I, AV-SER-44-0-66, A. Howard Hasbrook, Aviation Crash Injury Research of Cornel1 University 8 . "Janes, A11 the Worlds Aircraft, 1966-67", McGraw-Hill.
9. CAB AccidentInvestigation Report taken from Aviation Week and Space Technology, September 6 , 1966, p. 113.
10. "Investigation of Crew Escape System Surface Impact Tech- niques for Advanced Aerospace Vehicles" ASD-TDR-63-173.
11. "Limited Investigation of Crushable Structures for Accelera- tion Protection of Occupants of Vehicles at Low Impact Speeds" NASA Technical Note D-158, October 1959 12. "Energy Absorption Properties of Aluminum Honeycomb", Hexcel Products, Inc., TSB-110, January 1, 1960.
13. "Phase Iv - Investigation of Strength of Isolated Verte-
brae" October 1966, Technology Inc. TI 1313-66-4 NASw- 1313 L . S . Higgins, J . F . Crocker