19770004090 · Landing practices of general aviation pilots in single-engine light airplanes

N A S A TECHNICAL N O T E , M N O?

n z c w z

LANDING PRACTICES

OF GENERAL AVIATION PILOTS

IN SINGLE-ENGINE LIGHT AIRPLANES

Maxwell W. Goode, Xhomus C. O’Bryun, Kenneth R. Yenni, Robert L. Cannaduy,

and Marna E l . Mayo

Langley Research Center

Hanipton, Vu. 23665

N A T I O N A L A E R O N A U T I C S A N D SPACE A D M I N I S T R A T I O N W A S H I N G T O N , 0. C. OCTOBER 1976 TECH LIBRARY KAFB, NM 2. Government Accession No. 1. Report No.

N A S A TN D-8283 I l l l l l l 1 1 # 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 l l ~ 1 1

I ~~~~~~

013405b 4. Title and Subtitle October 1976 LANDING PRACTICES OF GENERAL AVIATION PILOTS I N SINGLE-ENGINE LIGHT AIRPLANES 6. Performing Organization Code 7. Author(s) 8. Performing Organization Report No.

M a x w e l l W. Goode, Thomas C. O'Bryan, Kenneth R. Yenni, L-10878 Robert L. Cannaday, and Marna H. Mayo 10. Work Unit No.

9. Performing Organization Name and Address 505-10-11-01 N A S A Langley Research Center 11. Contract or Grant No.

Hampton, VA 23665 13. Type of Report'and Period Covered 2. Sponsoring Agency Name and Address Technical Note National Aeronautics and Space Administration 14. Sponsoring Agency Code Washington, DC 20546 5. Supplementary Notes Technical Film Supplement L-1208 a v a i l a b l e on r e q u e s t .

6. Abstract The methods and techniques used by a group of g e n e r a l a v i a t i o n p i l o t s during t h e landing phase of l i g h t a i r p l a n e o p e r a t i o n s have been documented. This r e p o r t contains t h e results of 616 landings made by 22 p i l o t s i n 2 modern, four-place, single-engine, l i g h t a i r p l a n e s (one having a low wing and t h e o t h e r , a high wing).

The landings were made on b o t h a long runway (1524 m (5000 f t ) ) and a s h o r t runway (762 m (2500 f t ) ) ; both runways were considered t y p i c a l of t h o s e used i n g e n e r a l a v i a t i o n . The r e s u l t s g e n e r a l l y show t h a t most of t h e approaches were fast with considerable f l o a t i n g during t h e flares and with touchdowns t h a t w e r e r e l a t i v e l y f l a t or nose-low.

7. Key-Words (Suggested by Authoris) ) 18. Distribution Statement Light a i r c r a f t landing U n c l a s s i f i e d - Unlimited Light a i r c r a f t p i l o t performance 22. Price' 9. Security Classif. (of this report) 20. Security Classif. (of this page) 21. No. of Pages U n c l a s s i f i e d Unc l a s s i f i ed 48 $3 75 - L A N D I N G PRACTICES OF G E N E R A L A V I A T I O N P I L O T S I N SINGLE-ENGINE L I G H T AIRPLANES Maxwell W . G o o d e , Thomas C . O ' B r y a n , K e n n e t h R . Y e n n i , R o b e r t L . C a n n a d a y , a n d Marna H . Mayo L a n g l e y R e s e a r c h C e n t e r SUMMARY T h e m e t h o d s a n d t e c h n i q u e s u s e d by a g r o u p o f g e n e r a l a v i a t i o n p i l o t s d u r i n g t h e l a n d i n g p h a s e o f l i g h t a i r p l a n e o p e r a t i o n s h a v e b e e n d o c u m e n t e d . T h i s r e p o r t c o n t a i n s t h e r e s u l t s o f 616 l a n d i n g s made by 22 p i l o t s i n 2 m o d e r n , f o u r - p l a c e , s i n g l e - e n g i n e , l i g h t a i r p l a n e s ( o n e h a v i n g a low w i n g a n d t h e o t h e r , a h i g h w i n g ) . The l a n d ' i n g s were made on b o t h a l o n g r u n w a y ( 1 5 2 4 m ( 5 0 0 0 f t > > a n d a s h o r t r u n w a y ( 7 6 2 m ( 2 5 0 0 f t ) ) ; b o t h r u n w a y s were c o n s i d e r e d t y p i - c a l o f t h o s e u s e d i n g e n e r a l a v i a t i o n . The r e s u l t s g e n e r a l l y show t h a t m o s t o f t h e a p p r o a c h e s were f a s t w i t h c o n s i d e r a b l e f l o a t i n g d u r i n g t h e f l a r e s a n d w i t h t o u c h d o w n s t h a t were r e l a t i v e l y f l a t o r n o s e - l o w .

I N T R O D U C T I O N T h e N a t i o n a l A e r o n a u t i c s a n d S p a c e A d m i n i s t r a t i o n ( N A S A ) h a s u n d e r t a k e n a r e s e a r c h p r o g r a m t o d o c u m e n t m e t h o d s a n d t e c h n i q u e s u s e d by g e n e r a l a v i a t i o n p i l o t s t o l a n d a i r p l a n e s . T h i s e f f o r t w a s p r o m p t e d by t h e g e n e r a l a v i a t i o n s a f e t y r e c o r d s i n c l u d e d i n r e f e r - e n c e 1 . T h e s e r e p o r t s i n d i c a t e t h a t most a c c i d e n t s u n d e r v i s u a l f l i g h t r u l e s (VFR) o c c u r d u r i n g t h e l a n d i n g p h a s e o f s i n g l e - e n g i n e , l i g h t a i r p l a n e s f l o w n f o r p l e a s u r e . I n t h e v a s t m a j o r i t y o f t h e s e a c c i d e n t s , t h e p i l o t i s t h e c a u s e o r a t l e a s t a c o n t r i b u t i n g f a c t o r .

Many f a c t o r s i n f l u e n c e p i l o t p e r f o r m a n c e t o v a r y i n g d e g r e e s ; some o f t h e s e f a c t o r s a r e d e f i n e d i n r e f e r e n c e 2 w i t h t h e d e g r e e of i n f l u e n c e f o r each f a c t o r .

F o r t h i s s t u d y , two m o d e r n , f o u r - p l a c e , s i n g l e - e n g i n e , l i g h t a i r p l a n e s ( o n e h a v i n g a low w i n g a n d t h e o t h e r , a h i g h w i n g ) were leased f r o m a f i x e d - b a s e o p e r a t o r ( F B O ) . A c a d r e o f g e n e r a l a v i - a t i o n p i l o t s w i t h v a r i o u s b a c k g r o u n d s a n d e x p e r i e n c e s was p r o v i d e d by t h e FBO t o p e r f o r m a s e r i e s o f l a n d i n g s b o t h o n a l o n g r u n w a y ( 1 5 2 4 m ( 5 0 0 0 f t ) ) a n d a s h o r t r u n w a y ( 7 6 2 m ( 2 5 0 0 f t ) ) . A p p r o a c h a n d l a n d i n g d a t a were c o l l e c t e d f o r a p p r o x i m a t e l y 150 l a n d i n g s o n each runway f o r e a c h a i r p l a n e w i t h g r o u n d - t r a c k i n g a n d a i r b o r n e d a t a s y s t e m s . A summary o f t h e r e s u l t s o f t h i s l a n d i n g progPam i s p r e s e n t e d t o c h a r a c t e r i z e t y p i c a l p r i v a t e p i l o t p e r f o r m a n c e d u r i n g t h e l a n d i n g p h a s e of f l i g h t i n d a y l i g h t VFR c o n d i t i o n s . P r e l i m i - n a r y results f o r t h e l o w - w i n g a i r p l a n e p h a s e o f t h i s p r o g r a m a r e p r e s e n t e d i n r e f e r e n c e 3.

A m o t i o n - p i c t u r e f i l m s u p p l e m e n t h a s b e e n p r e p a r e d a n d i s a v a i l a b l e o n l o a n . A r e q u e s t c a r d form a n d a d e s c r i p t i o n o f t h e f i l m w i l l b e f o u n b a t t h e back o f t h i s r e p o r t .

T E S T EQUIPMENT T h e a i r p l a n e s u s e d i n t h i s s t u d y ( f i g . 1 ) were c h o s e n a s b e i n g r e p r e s e n t a t i v e o f t h e m o s t w i d e l y u s e d a i r p l a n e s i n g e n e r a l a v i a t i o n p r i v a t e f l y i n g . B o t h a i r p l a n e s were l e a s e d from FBO a n d were u s e d i n h i s f l i g h t t r a i n i n g a n d r e n t a l p r o g r a m s . The t e s t v e h i c l e s were s i n g l e - e n g i n e , f o u r - p l a c e a i r p l a n e s w i t h f i x e d t r i c y c l e l a n d i n g g e a r .

One o f t h e a i r p l a n e s h a d a low w i n g a n d t h e o t h e r h a d a h i g h w i n g .

The d e t a i l s a n d s p e c i f i c a t i o n s f o r each a i r p l a n e were o b t a i n e d from t h e r e s p e c t i v e a i r p l a n e o w n e r ' s m a n u a l s a n d a r e p r e s e n t e d i n t a b l e s I a n d 11. O t h e r t h a n w i n g l o c a t i o n , t h e r e a r e s e v e r a l b a s i c d i f f e r - e n c e s b e t w e e n t h e two a i r p l a n e s : ( 1 ) t h e l o n g i t u d i n a l c o n t r o l s y s t e m f o r t h e low-wing a i r p l a n e u s e d a s t a b i l a t o r , whereas t h e h i g h - w i n g a i r p l a n e u s e d a c o n v e n t i o n a l f i x e d h o r i z o n t a l s t a b i l i z e r a n d e l e v a - t o r ; (2) t h e l o w - w i n g a i r p l a n e was e q u i p p e d w i t h r u d d e r t r i m a n d t h e h i g h - w i n g o n e w a s n o t ; a n d ( 3 ) t h e low-wing a i r p l a n e had m a n u a l l y o p e r a t e d f l a p s w i t h f o u r d i s c r e t e s e t t i n g s ( O o , I O o , 25O, a n d 4 0 ° ) , whereas t h e h i g h - a i r p l a n e h a d e l e c t r i c a l l y o p e r a t e d f l a p s w i t h i n f i n i t e s e t t i n g s b e t w e e n Oo a n d 40'.

The a i r p l a n e s were i n s t r u m e n t e d t o m e a s u r e a n d r e c o r d 21 d i f - f e r e n t f l i g h t p a r a m e t e r s i n c l u d i n g a i r s p e e d , p i t c h a t t i t u d e , f l a p p o s i t i o n , a n d a l t i t u d e . The i n s t r u m e n t a t i o n s y s t e m c o n s - i s t e d o f s e n s o r s l o c a t e d t h r o u g h o u t t h e a i r p l a n e , a s i g n a l c o n d i t i o n i n g p a c k a g e , a n d a c e n t r a l t a p e r e c o r d e r . I n t h e low-wing a i r p l a n e , t h e i n s t r u m e n t a t i o n p a c k a g e was l o c a t e d i n t h e b a g g a g e c o m p a r t m e n t ; i n t h e h i g h - w i n g a i r p l a n e , t h e p a c k a g e was l o c a t e d i n t h e r e a r p a s - s e n g e r c o m p a r t m e n t . T h e o n l y m o d i f i c a t i o n t o t h e i n s t r u m e n t p a n e l was t h e i n s t a l l a t i o n o f c o n t r o l s w i t c h e s f o r t h e r e c o r d i n g s y s t e m ; t h e s e s w i t c h e s were c e n t r a l l y l o c a t e d i n t h e p a n e l . T h e o n l y o b v i - o u s c h a n g e i n t h e e x t e r n a l a p p e a r a n c e o f t h e a i r p l a n e s was t h e t e s t boom p r o t r u d i n g from t h e l e f t w i n g t i p . T h i s boom was a p p r o x i m a t e l y 7 5 p e r c e n t o f t h e w i n g c h o r d i n l e n g t h a n d was i n s t a l l e d t o m e a s u r e a i r s p e e d , a n g l e o f a t t a c k , a n d a n g l e o f s i d e s l i p . A w e i g h t was a d d e d i n s i d e t h e r i g h t w i n g t i p t o c o u n t e r b a l a n c e t h e w e i g h t o f t h e t e s t boom. T h e c o m p l e t e a i r b o r n e d a t a s y s t e m i n c r e a s e d t h e b a s i c w e i g h t of t h e t e s t a i r p l a n e a p p r o x i m a t e l y 8 6 . 2 k g ( 1 9 0 l b ) .

The f l i g h t c h a r a c t e r i s t i c s o f b o t h a i r p l a n e s were i n v e s t i g a t e d by N A S A r e s e a r c h p i l o t s b e f o r e a n d a f t e r t h e m o d i f i c a t i o n s f o r i n s t r u m e n t a t i o n . T h e q u a l i t a t i v e r e s u l t s o f t h e s e t e s t s i n d i c a t e d t h a t t h e i n s t a l l a t i o n o f t h e i n s t r u m e n t s y s t e m s h a d n e g l i g i b l e e f f e c t s o n t h e h a n d l i n g c h a r a c t e r i s t i c s o f b o t h a i r p l a n e s . A i r - s p e e d c a l i b r a t i o n s were c o n d u c t e d t o c o r r e l a t e t h e p i l o t ' s i n d i - c a t e d a i r s p e e d w i t h t h e r e c o r d e d i n d i c a t e d a i r s p e e d a s m e a s u r e d by t h e t e s t boom. The a i r s p e e d c a l i b r a t i o n c u r v e s f o r each a i r - p l a n e a r e p r e s e n t e d i n f i g u r e 2 . The r e c o r d e d i n d i c a t e d a i r s p e e d was c h o s e n a s t h e common b a s i s f o r c o m p a r i s o n ; t h e r e f o r e , u n l e s s o t h e r w i s e s t a t e d , a l l a i r s p e e d s r e f e r r e d t o i n t h i s r e p o r t a r e e x p r e s s e d i n terms o f t h e recorded i n d i c a t e d a i r s p e e d . I n a d d i t i o n , t h e w i n g s - l e v e l , p o w e r - o f f , s t a l l s p e e d r a n g e o f each a i r p l a n e was d o c u m e n t e d f o r v a r i o u s f l a p s e t t i n g s . T h e s e t e s t s were c o n d u c t e d i n a c c o r d a n c e w i t h t h e p r o c e d u r e s s p e c i f i e d i n p a r t 2 3 . 2 0 1 o f t h e F e d e r a l A v i a t i o n R e g u l a t i o n s ( r e f . 4 ) . T h e s t a l l s p e e d s u s e d i n t h e f i g u r e s a r e t h e m e a s u r e d s t a l l s p e e d s o f t h e r e s p e c t i v e a i r - p l a n e s a t t h e n o m i n a l t e s t w e i g h t , w h e r e a s t h e s t a l l s p e e d s i n t h e t a b l e s r e f l e c t t h e m a n u f a c t u r e r s ' s p e c i f i e d v a l u e s .

A g r o u n d - t r a c k i n g s y s t e m was u s e d t o o b t a i n t h e f l i g h t - p a t h d a t a d u r i n g - t h e f i n a l s t a g e s o f t h e a p p r o a c h e s a n d t h e t o u c h d o w n d a t a . T h i s s y s t e m , shown i n f i g u r e 3 , c o n s i s t e d o f a 16-mm m o t i o n - p i c t u r e camera a n d a l a r g e p h o t o g r a p h i c g r i d . The g r i d was l o c a t e d p a r a l l e l t o t h e r u n w a y a n d b e t w e e n t h e camera a n d t h e runway s o t h a t b o t h t h e a i r p l a n e a n d p o r t i o n s o f t h e g r i d were p h o t o g r a p h e d s i m u l t a n e o u s l y d u r i n g t h e f i n a l a p p r o a c h a n d l a n d i n g . The e x a c t l o c a t i o n of t h e s y s t e m was s u r v e y e d w i t h r e s p e c t t o t h e l a n d i n g e n d o f t h e r u n w a y . T h e g r i d c o n s i s t e d o f a s e r i e s o f v e r t i c a l a n d h o r i z o n t a l p l a s t i c s t r i p s f a s t e n e d a t t h e i n t e r s e c t i o n s t o f o r m s q u e r e s w i t h s i d e s 0 . 6 m ( 2 f t ) i n l e n g t h . The t o t a l s y s t e m c o n s i s t e d o f t e n 6.7-m-long ( 2 2 - f t - l o n g ) s e c t i o n s w i t h r i g i d a l u m i n u m p o l e s b e t w e e n e a c h s e c t i o n .

The s u p p o r t p o l e s were a d j u s t a b l e t o c o m p e n s a t e f o r u n e v e n t e r r a i n a n d t o s e t t h e d e s i r e d e l e v a t i o n o f t h e g r i d . T h e o v e r a l l g r i d s y s t e m was 3.05 m ( I O f t ) h i g h a n d 6 7 . 0 6 m ( 2 2 0 f t ) l o n g .

Normal p h o t o g r a m m e t r i c t e c h n i q u e s were u s e d t o o b t a i n t h e t r a j e c t o r y d a t a f r o m t h e f i l m . All m e a s u r e m e n t s were b a s e d o n t h e p o s i t i o n s o f t h e t i p o f t h e a i r p l a n e n o s e a n d t h e v e r t i c a l t a i l w i t h r e s p e c t t o t h e p o s i t i o n o f t h e p h o t o g r a p h i c g r i d s e e n i n e a c h p i c t u r e frame. T h e s e m e a s u r e m e n t s were c o n v e r t e d t o t h e a t t i t u d e of t h e a i r p l a n e a n d t h e l o c a t i o n o f i t s c e n t e r o f g r a v i t y w i t h r e s p e c t t o t h e r u n w a y t h r e s h o l d . F o r p h o t o g r a p h i c a n a l y s i s p u r p o s e s , a l l l a n d i n g s were a s s u m e d t o b e o n t h e c e n t e r l i n e o f t h e r u n w a y . E r r o r s r e s u l t i n g f r o m t h i s a s s u m p t i o n were f o u n d t o b e n e g l i g i b l e f o r t h e p u r p o s e o f t h i s s t u d y . A f i e l d s u r v e y o f a t y p i c a l g r i d i n s t a l l a t i o n i n d i c a t e d a t r a c k i n g a c c u r a c y w i t h i n k 0 . 3 m ( & I f t ) .

Wind d i r e c t i o n a n d v e l o c i t y a t 3 . 0 5 m (IO f t ) a n d a t 9 . 1 4 m ( 3 0 f t ) a b o v e g r o u n d l e v e l were m e a s u r e d a n d r e c o r d e d f o r e a c h I l a n d i n g . A p o r t a b l e w e a t h e r s t a t i o n w i t h w i n d d e t e c t i o n e q u i p m e n t was l o c a t e d n e a r t h e r u n w a y f o r t h i s p u r p o s e . ( S e e f i g . 4 . ) T E S T SUBJECTS A c a d r e o f 2 2 p i l o t s s e l e c t e d b y FBO a n d a p p r o v e d b y N A S A p e r - f o r m e d t h e l a n d i n g s i n t h i s p r o g r a m . T h e t e s t s u b j e c t s ' e x p e r i e n c e a n d b a c k g r o u n d r a n g e d f r o m s t u d e n t p i l o t s w i t h 30 h o u r s f l i g h t time t o a c o m m e r c i a l p i l o t w i t h a b o u t 1000 h o u r s f l i g h t time. A c o m p l e t e l i s t o f t h e t e s t s u b j e c t s w i t h e x p e r i e n c e , f l i g h t t i m e , a n d number of l a n d i n g s p e r f o r m e d i s p r e s e n t e d i n t a b l e 111. A l l t h e s u b j e c t ' s were q u a l i f i e d t o o p e r a t e t h e t e s t a i r p l a n e i n a c c o r d a n c e w i t h c u r - r e n t F e d e r a l A v i a t i o n A d m i n i s t r a t i o n r u l e s a n d r e g u l a t i o n s . . T e n o f t h e p i l o t s f l e w i n t h e l o w - w i n g a i r p l a n e p h a s e o f t h e p r o g r a m a n d 12 f l e w i n t h e h i g h - w i n g p h a s e . The o r i g i n a l i n t e n t w a s f o r each p i l o t t o p e r f o r m l a n d i n g s o n b o t h t h e l o n g a n d s h o r t r u n w a y s f o r t h e p h a s e o f t h e p r o g r a m i n w h i c h h e was i n v o l v e d ; h o w e v e r , f o r v a r i o u s r e a s o n s , t h i s i n t e n t w a s n o t c o m p l e t e l y m e t , a s c a n b e n o t e d , f r o m t a b l e 111.

A I R P O R T S A N D RUNWAYS The a i r p o r t s c h o s e n f o r t h i s p r o g r a m were s e l e c t e d p r i m a r i l y b e c a u s e t h e y were c o n s i d e r e d r e p r e s e n t a t i v e o f a i r p o r t s u s e d by g e n - e r a l a v i a t i o n p i l o t s , a n d s e c o n d l y , b e c a u s e t h e y h a d a c l e a r a r e a a d j a c e n t t o t h e l a n d i n g r u n w a y t o a c c o m m o d a t e t h e g r o u n d - t r a c k i n g s y s t e m .

The a i r p o r t c h o s e n f o r t h e l o n g - r u n w a y l a n d i n g s w a s a l a r g e c o n t r o l l e d f i e l d s e r v i n g a m e t r o p o l i t a n a r e a . A p h o t o g r a p h o f t h i s f i e l d ( f i g . 5 ) s h o w s t w o , h a r d - s u r f a c e r u n w a y s ( 2 - 2 0 a n d 6 - 2 4 ) .

A l l l a n d i n g s were made o n r u n w a y 2-20 w h i c h was 1524 m ( 5 0 0 0 f t ) l o n g a n d 4 5 . 7 m ( 1 5 0 f t ) w i d e w i t h s i g n i f i c a n t c l e a r a r e a s l e a d i n g t o t h e t h r e s h o l d s . F i e l d e l e v a t i o n was 1 2 . 5 m ( 4 1 f t ) . The a i r p o r t h a n d l e d a s i g n i f i c a n t a m o u n t o f t r a f f i c , b o t h c i v i l a n d m i l i t a r y .

A t t i m e s t h e t r a f f i c was h e a v y ; t h i s n e c e s s i t a t e d m o d i f i c a t i o n s o f t h e s t a n d a r d t r a f f i c p a t t e r n s , u s u a l l y a n e x t e n d e d downwind w i t h a l o n g s t r a i g h t - i n f i n a l .

The s h o r t - r u n w a y a i r p o r t was a small u n c o n t r o l l e d f i e l d s e r v - i n g a r u r a l a r e a . T h e p h o t o g r a p h o f t h e f i e l d ( f i g . 6 ) s h o w s a s i n g l e , h a r d - s u r f a c e r u n w a y ( 1 8 - 3 6 ) . A l l l a n d i n g s were made o n r u n w a y 18 w h i c h was 7 6 2 m ( 2 5 0 0 f t ) l o n g a n d 1 5 . 2 m ( 5 0 f t ) w i d e w i t h a n e l e v a t i o n o f 9 . 1 m ( 3 0 f t ) . T h e a p p r o a c h t o t h e r u n w a y was o v e r water w i t h a t r e e l i n e a p p r o x i m a t e l y 4 0 2 m ( 1 / 4 m i l e ) from t h e t h r e s h o l d . The area b e t w e e n t h e t r e e l i n e a n d t h e t h r e s h o l d was a n o p e n f i e l d u n d e r c u l t i v a t i o n . T h e a i r p o r t h a d v e r y l i g h t t r a f f i c ; c o n s e q u e n t l y , t h e t e s t s u b j e c t s c o u l d f l y t h e p a t t e r n w i t h o u t i n t e r f e r e n c e .

TEST P R O C E D U R E S A l l t h e p i l o t s were b r i e f e d o n t h e p u r p o s e o f t h e s t u d y a n d t h e o p e r a t i o n o f t h e e q u i p m e n t p r i o r t o p a r t i c i p a t i n g i n t h e p r o - gram. T h e y were a s k e d t o make n o r m a l l a n d i n g s b a s e d o n t h e i r t r a i n i n g a n d e x p e r i e n c e . They were a l s o a s k e d t o t u r n t h e a i r b o r n e d a t a s y s t e m o n j u s t p r i o r t o or j u s t a f t e r t u r n i n g o n t o t h e f i n a l a p p r o a c h ; h o w e v e r , t h e o p e r a t i o n o f t h e a i r p l a n e a n d t h e p i l o t i n g t e c h n i q u e s were l e f t c o m p l e t e l y t o t h e d i s c r e t i o n o f t h e i n d i v i d u a l p i l o t . Each p i l o t was s c h e d u l e d t o make a maximum o f s i x l a n d i n g s i n a n y o n e d a y w i t h o u t p r i o r p r a c t i c e o n t h a t d a y . T h i s s i t u a t i o n was i m p o s e d t o m i n i m i z e p r a c t i c e e f f e c t s a n d t o o b t a i n d a t a f o r e a c h p i l o t u n d e r d i f f e r e n t w i n d c o n d i t i o n s . I f f o r some r e a s o n t h e p i l o t f a i l e d t o t u r n t h e a i r b o r n e d a t a s y s t e m o n d u r i n g some o f t h e l a n d i n g s , t h e maximum was e x t e n d e d t o c o v e r s i x d a t a l a n d - i n g s . I n o r d e r t o h e l p a l l e v i a t e t r a f f i c c o n g e s t i o n o n t h e l o n g r u n w a y , t o u c h - a n d - g o l a n d i n g s w i t h a s i g n i f i c a n t g r o u n d r o l l were p e r m i t t e d . T h e s e l a n d i n g s were p e r m i t t e d o n t h e a s s u m p t i o n t h a t t h i s p r o c e d u r e w o u l d n o t s i g n i f i c a n t l y a f f e c t t h e n o r m a l l a n d i n g p e r f o r m a n c e s . A l l t h e l a n d i n g s o n t h e s h o r t r u n w a y were c o m p l e t e d t o a f u l l s t o p .

RESULTS A N D DISCUSSION T h e r e s u l t s o f t h i s l a n d i n g p e r f o r m a n c e s t u d y c o v e r a t o t a l of 616 l a n d i n g s made i n b o t h a i r p l a n e s a t b o t h r u n w a y s . A t o t a l o f 299 l a n d i n g s were made i n t h e l o w - w i n g a i r p l a n e ( 1 4 4 o n t h e l o n g runway a n d 155 on t h e s h o r t r u n w a y ) a n d 317 l a n d i n g s were made i n t h e h i g h - w i n g a i r p l a n e ( 1 6 3 o n t h e l o n g r u n w a y a n d 1 5 4 o n t h e s h o r t r u n w a y ) .

F l i g h t C o n d i t i o n s A l l l a n d i n g s were made e s s e n t i a l l y a t sea l e v e l w i t h a n a m b i e n t t e m p e r a t u r e r a n g e from 21' C t o 32' C (70' F t o 90' F).

The w i n d c o n d i t i o n s f o r each l a n d i n g a r e p r e s e n t e d i n f i g u r e 7.

T h e d a t a were r e c o r d e d a t t h e time o f each l a n d i n g r e l a t i v e t o t h e a c t i v e runway a s m e a s u r e d a t 3.05 m ( 1 0 f t ) a b o v e g r o u n d l e v e l . These d a t a a r e p r e s e n t e d t o show t h a t t h e l a n d i n g s were made w i t h a w i d e r a n g e o f w i n d c o n d i t i o n s , i n c l u d i n g v a r i a b l e w i n d s t h a t r e s u l t e d i n some l a n d i n g s b e i n g made w i t h a t a i l - w i n d c o m p o n e n t . T h e s h o r t - r u n w a y a i r p o r t was l o c a t e d a c o n s i d e r a b l e d i s t a n c e f r o m t h e n o r m a l base o f o p e r a t i o n s ; c o n s e q u e n t l y , i t was more d i f f i c u l t t o c o n d u c t t e s t s t h e r e u n d e r f a v o r a b l e w i n d c o n d i t i o n s t h a n i t was a t t h e l o n g r u n w a y w h i c h was t h e n o r m a l base o f o p e r a t i o n s . A s a r e s u l t , more l a n d i n g s w i t h a t a i l - w i n d c o m p o n e n t were made a t t h e s h o r t r u n w a y t h a n a t t h e l o n g r u n w a y .

The p i l o t s were i n f o r m e d o f t h e w i n d c o n d i t i o n s a t t h e t i m e , a n d tests were c o n t i n u e d o n l y when t h e p i l o t s j u d g e d t h a t t h e t a i l w i n d s d i d n o t a d v e r s e l y a f f e c t t h e i r l a n d i n g p e r f o r m a n c e .

T r a f f i c P a t t e r n s A l l t h e p i l o t s were f a m i l i a r w i t h t h e a i r p o r t u s e d f o r t h e l o n g - r u n w a y l a n d i n g s s i n c e i t was t h e i r n o r m a l base of. o p e r a t i o n .

The a p p r o a c h e s were a l l I t l e f t - h a n d " t r a f f i c p a t t e r n s a n d e n t r y was n o m i n a l l y 2 4 4 m ( 8 0 0 f t ) a b o v e g r o u n d l e v e l . G e n e r a l l y , t h e p a t t e r n s c o u l d b e c h a r a c t e r i z e d as b e i n g s t a n d a r d ( r e f . 5 ) . H o w - e v e r , as m e n t i o n e d p r e v i o u s l y , t h e a i r p o r t h a n d l e d a s i g n i f i c a n t a m o u n t of t r a f f i c w h i c h o c c a s i o n a l l y n e c e s s i t a t e d m o d i f y i n g t h e t r a f f i c p a t t e r n t o p r o v i d e s p a c i n g b e t w e e n a i r p l a n e s . T h e s e p a t - t e r n m o d i f i c a t i o n s o c c u r r e d o n l y a b o u t 10 p e r c e n t o f t h e time.

Most o f t h e p i l o t s were u n f a m i l i a r w i t h t h e a i r p o r t u s e d f o r t h e s h o r t - r u n w a y l a n d i n g s . The a i r p o r t was u n c o n t r o l l e d , w i t h a n i n s u f f i c i e n t v o l u m e o f t r a f f i c t o a f f e c t t h e l a n d i n g p a t t e r n s t o a n y s i g n i f i c a n t d e g r e e . Most o f t h e p i l o t s s t a t e d t h a t t h e y b a s e d t h e i r l a n d i n g p a t t e r n g e o m e t r y o n e x p e r i e n c e i n j u d g i n g d i s t a n c e f r o m t h e r u n w a y w i t h o u t s p e c i f i c r e f e r e n c e t o g r o u n d f e a t u r e s . The t r a f f i c p a t t e r n s were a l l l e f t h a n d a n d e n t e r e d a t t h e s t a n d a r d 244-m ( 8 0 0 - f t ) a l t i t u d e . It was n o t e d t h a t t h e t r e e l i n e a p p r o x i - m a t e l y 4 0 2 m ( 1 / 4 m i l e ) from t h e t h r e s h o l d u s u a l l y p r o v i d e d e n o u g h t u r b u l e n c e t o s l i g h t l y u p s e t t h e a i r p l a n e s o n f i n a l a p p r o a c h . How- e v e r , some o f t h e a p p r o a c h e s were made i n s i d e t h e t r e e l i n e a n d were n o t s u b j e c t e d t o t h e u p s e t .

T r a j e c t o r i e s P r o f i l e s o f t h e a p p r o a c h t r a j e c t o r i e s m e a s u r e d w i t h t h e g r o u n d - t r a c k i n g s y s t e m f o r a l l l a n d i n g s o f b o t h a i r p l a n e s a t b o t h r u n w a y s a r e p r e s e n t e d i n f i g u r e 8. T h e s e p r o f i l e s were o b t a i n e d f r o m t h e a i r p l a n e p o s i t i o n d a t a t a k e n i n i n c r e m e n t s o f a b o u t 6 7 m ( 2 2 0 f t ) a l o n g t h e g r o u n d t r a c k o f t h e f i n a l a p p r o a c h a n d t o u c h - down. T h e l o n g - r u n w a y d a t a were i n i t i a t e d a p p r o x i m a t e l y 3 0 5 m ( 1 0 0 0 f t ) b e f o r e t h e r u n w a y t h r e s h o l d f o r b o t h a i r p l a n e s . The s h o r t - r u n w a y d a t a f o r t h e l o w - w i n g a i r p l a n e were l i m i t e d t o a b o u t 61 m ( 2 0 0 f t ) b e f o r e t h e t h r e s h o l d b e c a u s e o f a l i m i t e d f i e l d o f v i e w c r e a t e d by a g r o u p o f t r e e s . H o w e v e r , f o r t h e s h o r t - r u n w a y l a n d i n g s w i t h t h e h i g h - w i n g a i r p l a n e , t h e g r o u n d - t r a c k i n g s y s t e m was r e l o c a t e d ; t h e r e b y , a f i e l d o f v i e w o u t t o a p p r o x i m a t e l y 1 9 8 m ( 6 5 0 f t ) b e f o r e t h e t h r e s h o l d was p r o v i d e d . Shown i n f i g u r e 8 a r e t h e m e d i a n a n d t h e 5- t o 9 5 - p e r c e n t i l e s p r e a d o f t h e d a t a f o r t h e h e i g h t o f t h e a i r p l a n e a t t h e t h r e s h o l d a n d f o r t h e t o u c h d o w n d i s t a n c e of t h e a i r p l a n e from t h e t h r e s h o l d . Also i n c l u d e d i n t h e f i g u r e a r e 3' a n d 6O s l o p e s p a s s i n g t h r o u g h t h e m e d i a n . h e i g h t a t t h e t h r e s h o l d ; t h e s e s l o p e s a r e i n c l u d e d t o show t h e n o r m a l r a n g e o f g l i d e - p a t h a n g l e s , a s s u g g e s t e d i n r e f e r e n c e 6 .

G e n e r a l l y , t h e p r o f i l e s show c o n s i d e r a b l e v a r i a t i o n from s t r a i g h t o r u n i f o r m l y c u r v e d t r a j e c t o r i e s d e n o t i n g c o n s i d e r a b l e j o c k e y i n g on t h e p a r t o f most p i l o t s d u r i n g t h e f i n a l a p p r o a c h e s .

However, c e r t a i n i n d i v i d u a l p i l o t s d i d h a v e u n i f o r m l y c u r v e d t r a - j e c t o r i e s t h a t were r e l a t i v e l y c o n s i s t e n t . T h e a v e r a g e f l i g h t - p a t h a n g l e s u s e d b y t h e p i l o t s i n t h i s s t u d y were 4 . 7 O o n t h e l o n g runway a n d 5 . 9 O on t h e s h o r t r u n w a y f o r t h e l o w - w i n g a i r p l a n e , a n d 5.1' o n t h e l o n g r u n w a y a n d 6 . 1 ° o n t h e s h o r t r u n w a y f o r t h e h i g h - w i n g a i r p l a n e . T h e i n d i v i d u a l f l i g h t p a t h s , h o w e v e r , c o v e r e d a w i d e r a n g e o f v a l u e s from a s l o w as 1' t o a s h i g h as 1 4 O d u r i n g p o r t i o n s o f t h e a p p r o a c h e s . The a v e r a g e f l i g h t - p a t h a n g l e s were a b o u t l o s t e e p e r a t t h e s h o r t r u n w a y t h a n t h o s e a t t h e l o n g r u n - way. T h i s i s p r o b a b l y a d i r e c t r e s u l t o f t h e i n c r e a s e d f l a p d e f l e c t i o n a t t h e s h o r t r u n w a y .

The m e d i a n h e i g h t a t t h e t h r e s h o l d was l o w e r f o r t h e l o w - w i n g a i r p l a n e t h a n f o r t h e h i g h - w i n g a i r p l a n e o n b o t h r u n w a y s . W i t h r e s p e c t t o t h e r u n w a y s , b o t h a i r p l a n e s were b r o u g h t i n l o w e r over+ t h e t h r e s h o l d a t t h e s h o r t r u n w a y t h a n a t t h e l o n g r u n w a y .

The m e d i a n t o u c h d o w n p o s i t i o n was c l o s e r t o t h e t h r e s h o l d f o r t h e low-wing a i r p l a n e t h a n f o r t h e h i g h - w i n g a i r p l a n e o n b o t h r u n - ways. T h e s e t o u c h d o w n d i s t a n c e s f r o m t h e t h r e s h o l d were i n d i r e c t r e l a t i o n t o t h e m e d i a n h e i g h t s o f t h e r e s p e c t i v e a i r p l a n e s a t . t h e t h r e s h o l d . The s h o r t - r u n w a y l a n d i n g s were made c l o s e r t o t h e t h r e s h o l d t h a n t h e l o n g - r u n w a y l a n d i n g s . The m e d i a n t o u c h d o w n d i s t a n c e s f o r b o t h a i r p l a n e s o n b o t h r u n w a y s were w i t h i n t h e f i r s t t h i r d o f t h e r u n w a y , b u t w e l l b e y o n d t h e r u n w a y d e s i g n a t i o n n u m b e r s j u s t p a s t t h e t h r e s h o l d , as i s recommended i n r e f e r e n c e 5. T h e s e t o u c h d o w n d i s t a n c e s f r o m t h e t h r e s h o l d were l e s s t h a n 13 p e r c e n t of t h e runway l e n g t h on t h e l o n g runway a n d l e s s t h a n 16 p e r c e n t o n t h e s h o r t r u n w a y f o r b o t h a i r p l a n e s .

I

F i n a l Approach A i r s p e e d The a v e r a g e f i n a l a p p r o a c h a i r s p e e d s a n d t h e a v e r a g e f l a p d e f l e c t i o n s m e a s u r e d a t 5-sec i n t e r v a l s f o r t h e 6 0 - s e c p e r i o d p r i o r t o t o u c h d o w n , w h i c h i n c l u d e s f l a r e a n d t o u c h d o w n , a r e p r e - s e n t e d i n f i g u r e 9 . A l s o i n c l u d e d i n t h e f i g u r e s a r e r e f e r e n c e a p p r o a c h s p e e d s , w h i c h a r e i n t e r p o l a t e d v a l u e s o f t h e m a n u f a c - t u r e r s ' recommended a p p r o a c h s p e e d s u s i n g t h e a v e r a g e f l a p d e p l o y - m e n t a t each time p e r i o d , a n d t h e m e a s u r e d s t a l l s p e e d s o f t h e r e s p e c t i v e a i r p l a n e s a t t h e n o m i n a l t e s t w e i g h t . These r e f e r e n c e s p e e d s were c a l c u l a t e d as a m e a n s o f i n t e r p r e t i n g t h e a p p r o a c h s p e e d r e c o m m e n d a t i o n a n d b e c a u s e t h e m a n u f a c t u r e r s ' p u b l i s h e d v a l - u e s were n o t d i r e c t l y a p p l i c a b l e t o t h e a c t u a l f l i g h t c o n d i t i o n s .

The mean f i n a l a p p r o a c h a i r s p e e d a n d t h e s t a n d a r d d e v i a t i o n a r e p r e s e n t e d i n t a b l e I V .

The d a t a show t h a t , f o r t h e most p a r t , t h e p i l o t s flew t h e f i n a l a p p r o a c h e s w i t h a n a v e r a g e s p e e d c o n s i d e r a b l y f a s t e r t h a n t h e r e f e r e n c e s p e e d s . The e x c e p t i o n t o t h i s i s f o r t h e low-wing a i r - p l a n e o n t h e s h o r t r u n w a y d u r i n g t h e f i n a l 40 s e c p r i o r t o t o u c h - down. R e f e r e n c e 7 , a n F A A f l i g h t test g u i d e f o r a p r i v a t e p i l o t a p p l i c a n t , s p e c i f i e s t h a t t h e f i n a l a p p r o a c h s p e e d s h o u l d b e " e q u a l t o 1 . 3 times t h e s t a l l i n g s p e e d i n l a n d i n g c o n f i g u r a t i o n (1.3Vso) o r t h e f i n a l a p p r o a c h s p e e d p r e s c r i b e d by t h e m a n u f a c t u r e r . " The a c c e p t a b l e l e v e l o f p e r f o r m a n c e i s e x p e c t e d t o be w i t h i n + 5 k n o t s o f t h e p r o p e r f i n a l a p p r o a c h s p e e d . I f t h e m a n u f a c t u r e r s ' recom- mended a p p r o a c h s p e e d s were s e l e c t e d , t h e r e f e r e n c e a p p r o a c h s p e e d s p r e s e n t e d i n t h e f i g u r e show t h e a p p r o p r . i a t e f i n a l a p p r o a c h s p e e d s t o be u s e d by t h e p i l o t s . The s o l i d s y m b o l s i n f i g u r e 9 i n d i c a t e t h e time p e r i o d s a t w h i c h t h e a v e r a g e s p e e d s e x c e e d e d t h e t o l e r a n c e band b a s e d on t h e r e f e r e n c e v a l u e s . T h e s e s y m b o l s i n d i c a t e t h a t , i n g e n e r a l , t h e a v e r a g e a p p r o a c h s p e e d s u s e d by t h e p i l o t s i n t h i s s t u d y were f a s t e r t h a n t h e k 5 - k n o t t o l e r a n c e u n t i l w i t h i n 15 s e c o r l e s s o f t o u c h d o w n . The e x c e p t i o n t o t h i s r e s u l t i s f o r t h e low-wing a i r p l a n e o n t h e s h o r t r u n w a y i n w h i c h case t h e a v e r a g e s p e e d f e l l w i t h i n t h i s t o l e r a n c e a p p r o x i m a t e l y 45 sec p r i o r t o t o u c h d o w n .

The data a l s o show t h a t t h e p i l o t s g e n e r a l l y f l e w t h e f i n a l a p p r o a c h e s w i t h a c o n t i n u i n g r e d u c t i o n i n a i r s p e e d r a t h e r t h a n h o l d i n g a c o n s t a n t s p e e d a s i s recommended i n r e f e r e n c e 5. H o w - e v e r , r e f e r e n c e 8 r e c o m m e n d s a " g r a d u a l r e d u c t i o n i n p o w e r s e t t i n g a n d a i r s p e e d d u r i n g t h e f i n a l a p p r o a c h i n p r e p a r a t i o n f o r t h e r o u n d - o u t o r f l a r e f o r l a n d i n g . " A n o t h e r p o i n t o f i n t e r e s t shown by t h e d a t a i s t h a t t h e f i n a l a p p r o a c h s p e e d s o n t h e s h o r t r u n w a y were s l o w e r t h a n t h o s e o n t h e l o n g runway f o r b o t h a i r p l a n e s . T h i s c o r r e l a t e s d i r e c t l y w i t h t h e l a r g e r a v e r a g e f l a p d e f l e c t i o n u s e d a t t h e s h o r t r u n w a y . The r e d u c t i o n i n a v e r a g e a p p r o a c h s p e e d ( 6 t o 12 k n o t s ) , h o w e v e r , was much g r e a t e r t h a n t h e d i f f e r e n c e i n t h e r e f e r e n c e a p p r o a c h s p e e d s ( 1 t o 2 k n o t s ) . T h i s d i f f e r e n c e t e n d s t o i n d i c a t e t h a t t h e p i l o t s were m o r e c o n c e r n e d a b o u t t h e l e n g t h o f t h e r u n w a y a n d were p a y i n g much c l o s e r a t t e n t i o n t o t h e a i r s p e e d d u r i n g t h e a p p r o a c h t o t h e s h o r t r u n w a y t o a s s u r e l a n d i n g s w i t h c o m f o r t a b l e m a r g i n s b e t w e e n t h e s t o p p i n g p o i n t a n d t h e e n d o f t h e r u n w a y .

Touchdown A i r s p e e d The c u m u l a t i v e d i s t r i b u t i o n s o f a i r s p e e d a t t o u c h d o w n a r e p r e - s e n t e d i n f i g u r e 1 0 . I n c l u d e d i n t h e f i g u r e a r e t h e m e a s u r e d s t a l l s p e e d s o f t h e r e s p e c t i v e a i r p l a n e s a t t h e n o m i n a l t e s t w e i g h t a n d t h e r e f e r e n c e a p p r o a c h s p e e d s b a s e d o n t h e f l a p s e t t i n g s f o r t h e l a s t 10 sec o f t h e a p p r o a c h e s .

R e f e r e n c e 8 s t a t e s t h a t t h e t o u c h d o w n s p e e d s h o u l d b e a t a p p r o x i m a t e l y s t a l l i n g s p e e d . The d a t a g e n e r a l l y s h o w , h o w e v e r , t h a t t h e p i l o t s l a n d e d t h e a i r p l a n e s w i t h s p e e d s c o n s i d e r a b l y i n e x c e s s o f t h e s t a l l a i r s p e e d ; t h i s i s m o s t p r o b a b l y a d i r e c t r e s u l t o f t h e e x c e s s i v e a i r s p e e d u s e d d u r i n g t h e f i n a l a p p r o a c h .

The m e d i a n t o u c h d o w n s p e e d s r a n g e d from 13 p e r c e n t t o 48 p e r c e n t a b o v e t h e m e a s u r e d f l a p s - u p s t a l l s p e e d o f t h e r e s p e c t i v e a i r p l a n e s , a n d l e s s t h a n 6 p e r c e n t o f t h e l a n d i n g s f o r b o t h a i r p l a n e s a t b o t h r u n w a y s were w i t h i n t h e s t a l l s p e e d r a n g e s o f t h e a i r p l a n e .

E x c e p t f o r t h e l o w - w i n g a i r p l a n e a t t h e s h o r t r u n w a y , a r a t h e r h i g h p e r c e n t a g e o f t h e l a n d i n g s were made a t s p e e d s i n e x c e s s o f t h e r e f e r e n c e a p p r o a c h s p e e d s .

The d a t a a l s o show t h a t t h e t o u c h d o w n s p e e d s a t t h e s h o r t r u n w a y were s i g n i f i c a n t l y l e s s t h a n t h o s e a t t h e l o n g r u n w a y f o r b o t h a i r p l a n e s . The d i f f e r e n c e i n t o u c h d o w n s p e e d s b e t w e e n r u n - w a y s was a p p r o x i m a t e l y t h e same a s t h e d i f f e r e n c e i n t h e f i n a l a p p r o a c h s p e e d s o f t h e r e s p e c t i v e a i r p l a n e s . A g a i n , t h i s c o u l d b e i n d i c a t i v e o f t h e p i l o t s ' g e n e r a l c o n c e r n f o r t h e r u n w a y l e n g t h , a l t h o u g h i t i s e v i d e n t f r o m t h e s p e c i f i e d l a n d i n g d i s t a n c e s g i v e n i n t a b l e s I a n d I1 t h a t t h e a v a i l a b l e r u n w a y was more t h a n a d e q u a t e .

The d e s i g n a t e d s h o r t r u n w a y u s e d i n t h i s s t u d y was n o t , i n f a c t , a " s h o r t r u n w a y " r e q u i r i n g maximum p e r f o r m a n c e f r o m e i t h e r a i r p l a n e o r p i l o t t o a c h i e v e a n o r m a l l a n d i n g i n t h e a v a i l a b l e d i s t a n c e .

Touchdown P i t c h A t t i t u d e The c u m u l a t i v e d i s t r i b u t i o n s o f p i t c h a t t i t u d e at: t o u c h d o w n a r e p r e s e n t e d i n f i g u r e 1 1 . A l s o i n c l u d e d i n t h e f i g u r e i s a l i n e which i n d i c a t e s t h e i n - f l i g h t t h r e e - p o i n t t o u c h d o w n a t t i t u d e o f t h e r e s p e c t i v e a i r p l a n e s a n d w h i c h s e p a r a t e s t h e r e g i o n s o f n o s e - w h e e l a n d m a i n - w h e e l l a n d i n g a t t i t u d e s . I n g e n e r a l , t h e t o u c h d o w n p i t c h a t t i t u d e s s h o w l i t t l e t o no d i f f e r e n c e w i t h r e s p e c t t o r u n - w a y s , p a r t i c u l a r l y f o r t h e h i g h - w i n g a i r p l a n e . N o r m a l l y , o n e m i g h t e x p e c t t h e p i t c h a t t i t u d e s a t t h e s h o r t r u n w a y t o b e m o r e n o s e - h i g h t h a n a t t h e l o n g r u n w a y s i n c e t h e t o u c h d o w n s p e e d s were s l o w e r .

H o w e v e r , t h e f l a p d e f l e c t i o n was g r e a t e r f o r t h e s h o r t r u n w a y t h a n f o r t h e l o n g r u n w a y w h i c h w o u l d s h i f t t h e p i t c h a t t i t u d e a n d a i r - s p e e d r e l a t i o n s h i p t o a s l o w e r a i r s p e e d f o r t h e same p i t c h a t t i t u d e .

The d a t a g e n e r a l l y show t h a t t h e p i t c h a t t i t u d e s a t t o u c h d o w n were r e l a t i v e l y f l a t f o r b o t h a i r p l a n e s a t b o t h r u n w a y s . T h e m e d i a n t o u c h d o w n a t t i t u d e r a n g e d f r o m o n l y 1 . 4 O t o 2 . 6 O a b o v e t h e t h r e e - p o i n t a t t i t u d e ( p i t c h - u p ) . A s i g n i f i c a n t p e r c e n t a g e o f t h e l a n d i n g s was made i n w h i c h t h e n o s e w h e e l c o n t a c t e d t h e runway b e f o r e t h e main w h e e l s . A p p r o x i m a t e l y 1 2 p e r c e n t o f t h e l a n d i n g s were n o s e w h e e l f i r s t , e x c e p t f o r t h e low-wing a i r p l a n e a t t h e s h o r t r u n w a y w h e r e t h e p e r c e n t a g e was 2 2 p e r c e n t .

N o s e - w h e e l l a n d i n g s a r e a l m o s t i n v a r i a b l y a d i r e c t r e s u l t of a l l o w i n g a n a i r p l a n e t o t o u c h down w i t h a n e x c e s s i v e l y h i g h a i r - s p e e d . T h i s s i t u a t i o n c a n . p r o d u c e u n s t a b l e a i r p l a n e m o t i o n s , r e f e r r e d t o as p o r p o i s i n g o r w h e e l - b a r r o w i n g , w h i c h c a n l e a d t o s t r u c t u r a l damage o f t h e n o s e g e a r . D u r i n g t h i s s t u d y , p o r p o i s i n g was n o t e d d u r i n g some of t h e l a n d i n g s , b u t f o r t u n a t e l y t h e p i l o t s were a b l e t o c o p e w i t h t h e s i t u a t i o n a n d p r e v e n t a n y c a t a s t r o p h i c r e s u l t s .

R e f e r e n c e s 7 a n d 8 s t a t e t h a t i n n o s e - w h e e l t y p e a i r p l a n e s , t h e t o u c h d o w n s h o u l d b e made o n t h e m a i n w h e e l s w i t h l i t t l e t o n o w e i g h t o n t h e n o s e w h e e l . R e f e r e n c e 8 a l s o s t a t e s t h a t t h e t o u c h - down s p e e d s h o u l d b e a t a p p r o x i m a t e l y s t a l l i n g s p e e d . F o r t h e a i r - p l a n e s u s e d i n t h i s s t u d y , t h e p i t c h a t t i t u d e f o r t o u c h d o w n a t a p p r o x i m a t e l y s t a l l i n g s p e e d w o u l d b e s u f f i c i e n t l y h i g h t h a t t h e n o s e w h e e l w o u l d b e w e l l c l e a r o f t h e r u n w a y . If t h e p i l o t s i n t h i s s t u d y were l a n d i n g t h e a i r p l a n e s i n a p i t c h a t t i t u d e w h i c h w o u l d p e r m i t some w e i g h t o n t h e n o s e w h e e l , a s s t a t e d a b o v e , i t i s a p p a r e n t t h a t t h e t o u c h d o w n s p e e d s w o u l d b e c o n s i d e r a b l y h i g h e r t h a n t h e s t a l l i n g s p e e d .

A n a l y s i s o f I n d i v i d u a l A p p r o a c h e s a n d L a n d i n g s T w o i n d i v i d u a l a p p r o a c h e s a n d l a n d i n g s were s e l e c t e d t o e x e m p l i f y some d e s i r a b l e a n d u n d e s i r a b l e p i l o t i n g p r a c t i c e s .

T h e s e a p p r o a c h e s a n d l a n d i n g s were made by two d i f f e r e n t p i l o t s o n t h e l o n g runway w i t h t h e h i g h - w i n g a i r p l a n e . The f i n a l a p p r o a c h t r a j e c t o r i e s a r e p r e s e n t e d i n f i g u r e 1 2 . I n c l u d e d i n t h e f i g u r e a r e t h e mean a n d t h e 5- t o 9 5 - p e r c e n t i l e s p r e a d o f t h e d a t a f o r t h e a l t i t u d e o r h o r i z o n t a l p o s i t i o n o f t h e a i r p l a n e a t e n t r y i n t o t h e g r o u n d - t r a c k i n g g r i d a n d t h e a l t i t u d e o f t h e a i r p l a n e a t t h e t h r e s h o l d f o r a l l t h e l a n d i n g s p e r f o r m e d b y e a c h p i l o t . A mean 1 3 a p p r o a c h is p r e s e n t e d by a l i n e d r a w n b e t w e e n t h e two r e s p e c t i v e mean d a t a p o i n t s f o r e a c h p i l o t . T h i s i n f o r m a t i o n i s i n c l u d e d t o g i v e a p e r s p e c t i v e o f t h e i n d i v i d u a l a p p r o a c h e s w i t h r e s p e c t t o t h a t p i l o t ' s g e n e r a l p e r f o r m a n c e . T h e f i n a l a p p r o a c h a i r s p e e d a n d f l a p p o s i t i o n f o r e a c h o f t h e s e l e c t e d l a n d i n g s a r e p r e s e n t e d i n f i g u r e 13. I n c l u d e d i n t h e f i g u r e a r e t h e r e f e r e n c e a p p r o a c h s p e e d s a n d t h e m e a s u r e d s t a l l s p e e d r a n g e of t h e a i r p l a n e .

ADDroach A . - A p p r o a c h A ( f i g . 1 2 ) h a d a f l i g h t p a t h t h a t was e s s e n t i a l l y t h e same a s t h e mean a p p r o a c h f o r t h a t p i l o t . The a p p r o a c h was a s t r a i g h t , u n i f o r m g l i d e w i t h a f l i g h t - p a t h a n g l e o f a p p r o x i m a t e l y 3 . 5 O . The p i l o t b e g a n - t h e f l a r e n e a r t h e t h r e s h o l d a t a n a l t i t u d e o f a p p r o x i m a t e l y 2 . 1 m ( 7 f t ) a n d t o u c h e d down a b o u t 5 0 . 3 m ( 1 6 5 f t ) from t h e t h r e s h o l d . A t t o u c h d o w n , t h e a i r s p e e d was a p p r o x i m a t e l y 10 k n o t s a b o v e t h e s t a l l s p e e d , a n d t h e p i t c h a t t i t u d e , n o t s h o w n , was 5.9' a b o v e t h e t h r e e - p o i n t a t t i t u d e . The w i n d d u r i n g t h i s a p p r o a c h a n d l a n d i n g was a p p r o x i m a t e l y a 30' l e f t c r o s s w i n d o f 7 k n o t s .

T h i s a p p r o a c h a n d l a n d i n g s h o w a w e l l - p l a n n e d a n d w e l l - e x e c u t e d a p p r o a c h . The f i n a l a p p r o a c h s p e e d ( f i g . 1 3 1 , a l t h o u g h h i g h e r t h a n t h e r e f e r e n c e a p p r o a c h s p e e d , was s m o o t h a n d r e l a t i v e l y c o n s t a n t b e t w e e n t h e t r a n s i t i o n s a s s o c i a t e d w i t h f l a p d e f l e c t i o n a n d f l a r e . T h e a p p r o a c h l e a d i n g t o t h e f l a r e was a s t a b i l i z e d , s t e a d y f l i g h t p a t h d u r i n g w h i c h t h e p i l o t was r e d u c i n g h i s a i r s p e e d i n p r e p a r a t i o n f o r t h e f l a r e a n d l a n d i n g . T h e r e were n o n e c e s s a r y l a s t - m i n u t e c o r r e c t i o n s t o d i s t r a c t t h e p i l o t f r o m t h e b u s i n e s s o f f l a r i n g a n d l a n d i n g t h e a i r p l a n e . T h e t o u c h d o w n was made w i t h a p i t c h a t t i t u d e w e l l a b o v e t h e t h r e e - p o i n t a t t i t u d e a t a r e l a t i v e l y s l o w a i r s p e e d . I n g e n e r a l , t h i s a p p r o a c h a n d l a n d i n g was c o n s i d e r e d t o b e g o o d .

ADDroach B . - A p p r o a c h B ( f i g . 1 2 ) h a d a f l i g h t - p a t h a n g l e of a p p r o x i m a t e l y T o , w h i c h was a b o u t 1' s t e e p e r t h a n t h e mean s l o p e f o r t h a t p i l o t . T h e a p p r o a c h was c o n s i d e r a b l y h i g h e r t h a n t h e mean a p p r o a c h w i t h a n a l t i t u d e o f 2 0 . 4 m ( 6 7 f t ) a t t h e t h r e s h o l d . The p i l o t a l t e r e d h i s f l i g h t p a t h s e v e r a l t i m e s d u r i n g t h e a p p r o a c h .

1 4 Touchdown o c c u r r e d a p p r o x i m a t e l y 300.2 m ( 9 8 5 f t ) from t h e t h r e s h - o l d i n a f l a t p i t c h a t t i t u d e , a b o u t 0.5O a b o v e t h e t h r e e - p o i n t a t t i t u d e , w i t h a h i g h s i n k r a t e f o l l o w e d by t h r e e b o u n c e s t h a t b o r - d e r e d o n p o r p o i s i n g . The f i r s t b o u n c e i s shown i n t h e t r a j e c t o r y trace j u s t b e f o r e t h e a i r p l a n e l e f t t h e g r o u n d - t r a c k i n g g r i d . The f i n a l a p p r o a c h s p e e d ( f i g . 1 3 ) was w e l l a b o v e t h e r e f e r e n c e s p e e d a n d v a r i e d t h r o u g h s e v e r a l o s c i l l a t i o n s . The t o u c h d o w n s p e e d was c o n s i d e r a b l y a b o v e t h e s t a l l s p e e d o f t h e a i r p l a n e a n d o n l y 4 k n o t s slower t h a n t h e r e f e r e n c e a p p r o a c h s p e e d . The w i n d d u r i n g t h i s a p p r o a c h a n d l a n d i n g w a s a p p r o x i m a t e l y a n 80° l e f t c r o s s w i n d o f 7 k n o t s .

T h i s a p p r o a c h shows s e v e r a l d i s c r e p a n c i e s r e s u l t i n g from a p p a r e n t p o o r p l a n n i n g a n d p o o r e x e c u t i o n . The a p p r o a c h was h i g h a n d s t e e p w i t h a n e x c e s s i v e l y h i g h a i r s p e e d . The p i l o t d i d n o t a p p e a r t o h a v e . t h e a i r s p e e d u n d e r c o n t r o l . The i n c r e a s e i n f l a p d e f l e c t i o n a b o u t 40 s e c b e f o r e t o u c h d o w n i n i t i a t e d a t r a n s i e n t c o n d i t i o n t h a t a p p e a r e d t o l e a v e t h e p i l o t " b e h i n d t h e a i r p l a n e . " The h i g h s i n k r a t e a s s o c i a t e d w i t h t h e f a s t , s t e e p a p p r o a c h a p p a r e n t l y l e f t t h e p i l o t u n d e c i d e d a s t o when t o f l a r e t h e a i r - p l a n e . T h e r a t e o f d e s c e n t was n o t s u c c e s s f u l l y a r r e s t e d p r i o r t o t o u c h d o w n a n d t h e a i r s p e e d a t t o u c h d o w n was s o f a s t t h a t t h e n o s e w h e e l a l m o s t c o n t a c t e d t h e r u n w a y f i r s t . T h i s s e r i e s o f e v e n t s c a u s e d t h e a i r p l a n e t o b o u n c e down t h e r u n w a y . A l t h o u g h t h i s a p p r o a c h a n d l a n d i n g c u l m i n a t e d w i t h o u t damage t o t h e a i r - p l a n e , t h e r e was c e r t a i n l y much room f o r i m p r o v e m e n t i n t h e p i l o t ' s l a n d i n g p e r f o r m a n c e .

Q u a l i t a t i v e E v a l u a t i o n o f L a n d i n g s The q u a n t i t a t i v e d a t a o b t a i n e d from t h e g r o u n d - t r a c k i n g a n d f l i g h t - i n s t r u m e n t a t i o n s y s t e m s h a v e p r o v i d e d c o n s i d e r a b l e d e t a i l a b o u t t h e a p p r o a c h e s a n d l a n d i n g s made b y t h e p i l o t s d u r i n g t h i s s t u d y . However, some q u a l i t a t i v e e v a l u a t i o n s were d e s i r e d t o p r o v i d e b e t t e r i n s i g h t as t o t h e g e n e r a l q u a l i t y o f t h e l a n d i n g s .

For t h e s e e v a l u a t i o n s , t h e g r o u n d - t r a c k i n g m o t i o n p i c t u r e s were r e v i e w e d by a n N A S A research p i l o t who h o l d s a c e r t i f i e d f l i g h t i n s t r u c t o r ' s r a t i n g a n d by o n e o f t h e p r o j e c t e n g i n e e r s who i s a former m i l i t a r y a v i a t o r . I n p r e p a r i n g t h e i r e v a l u a t i o n s , t h e r e v i e w e r s s c r e e n e d many l a n d i n g s a n d d o c u m e n t e d d i s c r e p a n c i e s t o l o o k f o r d u r i n g t h e e v a l u a t i o n s . A l i s t o f t h e p r i m a r y d i s c r e p a n - c i e s w i t h a n e x p l a n a t i o n o f each i s g i v e n i n t a b l e V . O t h e r d i s - c r e p a n c i e s s u c h a s s l o w a n d p o r p o i s i n g were n o t e d l e s s t h a n 2 p e r - c e n t of t h e time a n d h a v e n o t b e e n i n c l u d e d .

The r e s u l t s o f t h e q u a l i t a t i v e e v a l u a t i o n s g i v e n i n terms o f t h e p e r c e n t a g e o f l a n d i n g s i n w h i c h each o f ' t h e d i s c r e p a n c i e s was n o t e d by each r e v i e w e r were a v e r a g e d a n d a r e p r e s e n t e d i n f i g u r e 1 4 .

The s h o r t - r u n w a y l a n d i n g s w i t h t h e low-wing a i r p l a n e were n o t e v a l - u a t e d s i n c e t h e l i m i t e d f i e l d o f v i e w d i d n o t a f f o r d t h e r e v i e w e r s s u f f i c i e n t time t o e v a l u a t e t h e a p p r o a c h e s t o t h e l a n d i n g s .

The q u a l i t a t i v e e v a l u a t i o n s s h o w t h a t t h e m a j o r i t y o f t h e a p p r o a c h e s was f a s t , r e g a r d l e s s o f t h e a i r p l a n e o r t h e r u n w a y .

T h i s was f o l l o w e d by c o n s i d e r a b l e f l o a t i n g d u r i n g t h e f l a r e a n d by t o u c h d o w n s t h a t were r e l a t i v e l y f l a t o r n o s e - l o w . T h e s e r e s u l t s a r e i n d i r e c t a g r e e m e n t w i t h t h e a n a l y s i s o f t h e q u a n t i t a t i v e d a t a .

The f l o a t i n g , n o s e - l o w t o u c h d o w n t e n d e n c i e s were m o s t p r o b - a d i r e c t r e s u l t of t h e f a s t a p p r o a c h e s . A l t h o u g h n o t s p e c i f - a b l y i c a l l y shown by t h e d a t a i n f i g u r e 1 4 , 30 t o 40 p e r c e n t o f t h e f a s t a p p r o a c h e s were a l s o h i g h , s t e e p a p p r o a c h e s . T h e f l a r e d i s c r e p a n - c i e s may v e r y w e l l h a v e a l s o b e e n a s s o c i a t e d w i t h t h e f a s t a p p r o a c h e s b u t were m o r e p r o b a b l y a s s o c i a t e d w i t h b o t h t h e d e v i a t i o n s f r o m a s t a b i l i z e d , s t e a d y f l i g h t p a t h a n d t h e h i g h , s t e e p a p p r o a c h e s . Q u i t e o b v i o u s l y , f l i g h t - p a t h d e v i a t i o n s d u r i n g t h e l a s t p o r t i o n o f a n a p p r o a c h p r i o r t o t h e f l a r e w i l l d i s t r a c t t h e p i l o t a n d w i l l i m p a i r h i s j u d g m e n t a s t o when t o f l a r e t h e a i r p l a n e . H i g h , s t e e p a p p r o a c h e s w i t h h i g h r a t e s o f d e s c e n t a r e a l s o d i f f i c u l t t o f l a r e w i t h c o n s i s - t e n c y s i n c e a c o n s i d e r a b l e f l a r e i s r e q u i r e d t o a r r e s t t h e r a t e o f d e s c e n t .

1 6 G e n e r a l Comments The r e v i e w e r s who e v a l u a t e d t h e l a n d i n g s from t h e g r o u n d - t r a c k i n g f i l m s made c e r t a i n p o i n t s a b o u t t h e o b s e r v . e d p i l o t i n g p r a c t i c e s . T h e s e v i e w s a r e e x p r e s s e d i n t h e f o l l o w i n g comments: ( 1 ) A l t h o u g h s e v e r a l p i l o t s c o n s i s t e n t l y a c h i e v e d r r g o o d l f l a n d i n g s , t h e r e were n u m e r o u s d e f i c i e n c i e s n o t e d i n a major p o r - t i o n of t h e a p p r o a c h e s a n d l a n d i n g s made by t h e o t h e r p i l o t s .

The d e f i c i e n c i e s a p p e a r t o b e p r i m a r i l y a s s o c i a t e d w i t h p i l o t i n g t e c h n i q u e s r a t h e r t h a n w i t h t h e a i r p l a n e s ; t h e c a t e g o r y o f t h e p i l o t s d i d n o t seem t o h a v e a n y b e a r i n g o n p e r f o r m a n c e .

( 2 ) The n o r m a l o p e r a t i n g e n v i r o n m e n t may h a v e h a d a d e f i n i t e b e a r i n g o n p i l o t p e r f o r m a n c e . T h e p i l o t s n o r m a l l y o p e r a t e d o u t o f t h e l a r g e m e t r o p o l i t a n a i r p o r t w i t h t h e l o n g runway u s e d d u r i n g t h e s e tests. A t s u c h a n a i r p o r t , w i t h l o n g , w i d e r u n w a y s a n d o b s t r u c t i o n - f r e e a p p r o a c h e s , t h e r e i s n o r e q u i r e m e n t t o l a n d a t a p r e c i s e p o i n t o n t h e r u n w a y t o p r e v e n t o v e r r u n n i n g t h e r u n w a y a s may b e n e c e s s a r y o n a s h o r t , n a r r o w r u n w a y w h e r e t h e m a r g i n f o r e r r o r w o u l d b e r e d u c e d o r a l m o s t n o n e x i s t e n t . T h i s s i t u a t i o n may l e a d t o c o m p l a c e n c y a n d may p e r m i t t h e a c c e p t a n c e o f l e s s t h a n optimum p e r f o r m a n c e .

( 3 ) F a i l u r e o f m o s t o f t h e p i l o t s t o f l y t h e a i r p l a n e s s l o w l y i s q u i t e a p p a r e n t . T h i s may b e a t t r i b u t e d t o s e v e r a l f a c t o r s . It c o u l d b e a s s u m e d t h a t t h o s e p i l o t s were f e a r f u l o f s t a l l i n g t h e a i r p l a n e s a n d were o v e r c o m p e n s a t i n g w i t h e x c e s s s p e e d . W h i l e e x c e s s s p e e d may p r e c l u d e t h e s t a l l , i t o b v i o u s l y i n t r o d u c e s o t h e r u n d e s i r a b l e c h a r a c t e r i s t i c s s u c h a s f l o a t i n g , n o s e - l o w t o u c h d o w n s , a n d b o u n c i n g t e n d e n c i e s . A n o t h e r e x p l a n a t i o n c o u l d b e t h a t t h e p i l o t s were a t t e m p t i n g t o make e x t r e m e l y smooth l a n d i n g s a n d t h o u g h t t h a t t h e e x c e s s s p e e d w o u l d h e l p " g r e a s e " t h e a i r p l a n e s o n t h e r u n w a y . It c o u l d a l s o b e a s s u m e d t h a t t h e p i l o t s were r e l u c t a n t t o a c c e p t t h e r e d u c e d a i r p l a n e r e s p o n s e c h a r a c t e r i s t i c s a s s o c i a t e d w i t h r e d u c e d a i r s p e e d s .

( 4 ) Even t h o u g h most o f t h e l a n d i n g s o b s e r v e d u n d e r t h e c o n - d i t i o n s o f t h i s s t u d y were j u d g e d t o b e a d e q u a t e , t h e y were n o t c o n s i d e r e d d e s i r a b l e . I f t h e p i l o t s e x h i b i t e d t h e same p i l o t i n g t e c h n i q u e s u n d e r o t h e r o p e r a t i n g c o n d i t i o n s s u c h as - moderate t o h e a v y t u r b u l e n c e , g u s t i n g c r o s s w i n d s , l e s s t h a n i d e a l r u n w a y c o n d i t i o n s , a n d h i g h e r ' p e r f o r m a n c e - l e s s t o l e r a n t a i r p l a n e s , many of t h e o b s e r v e d l a n d i n g s c o u l d h a v e r e s u l t e d i n u n s a f e s i t u a t i o n s n e c e s s i t a t i n g a " g o - a r o u n d " o r p o s s i b l y r e s u l t i n g i n a l a n d i n g a c c i d e n t .

C O N C L U D I N G R E M A R K S T h e r e s u l t s o f 616 l a n d i n g s made by 22 p i l o t s i n 2 m o d e r n , f o u r - p l a c e , s i n g l e - e n g i n e , l i g h t a i r p l a n e s ( o n e h a v i n g a low w i n g a n d t h e o t h e r , a h i g h w i n g ) h a v e b e e n d o c u m e n t e d . The l a n d i n g s were made o n b o t h a l o n g r u n w a y ( 1 5 2 4 m ( 5 0 0 0 f t ) ) a n d a s h o r t runway ( 7 6 2 . m ( 2 5 0 0 f t ) ) ; b o t h r u n w a y s were c o n s i d e r e d t y p i c a l o f r u n w a y s u s e d i n g e n e r a l a v i a t i o n . T h e f o l l o w i n g comments a r e b a s e d on t h e d a t a c o l l e c t e d d u r i n g t h e s t u d y : ( 1 ) The f i n a l a p p r o a c h t r a j e c t o r i e s s h o w e d c o n s i d e r a b l e v a r i a t i o n s from s t a b i l i z e d , s t e a d y f l i g h t p a t h s .

( 2 ) The a v e r a g e a p p r o a c h s p e e d s were g e n e r a l l y h i g h e r t h a n t h e recommended s p e e d s f o r t h e r e s p e c t i v e a i r p l a n e s .

( 3 ) The p i l o t s t e n d e d t o f l y d e c e l e r a t i n g a p p r o a c h e s d u r i n g t h e f i n a l a p p r o a c h r a t h e r t h a n m a i n t a i n i n g a s t a b i l i z e d s p e e d .

(4) C o n s i d e r a b l e f l o a t i n g d u r i n g t h e f l a r e was n o t e d .

( 5 ) The a v e r a g e t o u c h d o w n s p e e d s were w e l l a b o v e t h e m e a s u r e d s t a l l s p e e d r a n g e s o f t h e r e s p e c t i v e a i r p l a n e s , a n d a l a r g e p e r - c e n t a g e of t h e t o u c h d o w n s were made a t s p e e d s i n e x c e s s o f t h e recommended a p p r o a c h s p e e d s .

( 6 ) The t o u c h d o w n p i t c h a t t i t u d e s o f t h e a i r p l a n e s were g e n - e r a l l y f l a t o r n o s e - l o w .

( 7 ) Runway l e n g t h a p p e a r e d t o i n f l u e n c e t h e a p p r o a c h a n d l a n d i n g t e c h n i q u e s o f t h e p i l o t s o f b o t h a i r p l a n e s .

( 8 ) The l a n d i n g s g e n e r a l l y were c o n s i d e r e d t o b e a d e q u a t e a n d a l l were c o m p l e t e d w i t h o u t damage t o t h e a i r p l a n e s . H o w e v e r , many o f t h e l a n d i n g s e x h i b i t e d c h a r a c t e r i s t i c s t h a t r e d u c e d t h e m a r g i n o f s a f e t y a n d p r e s e n t e d t h e p o t e n t i a l f o r a n a c c i d e n t .

L a n g l e y R e s e a r c h C e n t e r N a t i o n a l A e r o n a u t i c s a n d S p a c e A d m i n i s t r a t i o n Hampton, V A 2 3 6 6 5 J u l y 1 4 , 1 9 7 6 REFERENCES 1 . A i r c r a f t A c c i d e n t R e p o r t s - B r i e f F o r m a t , U.S. C i v i l A v i a t i o n , I s s u e Number 2 , 1 9 7 0 A c c i d e n t s . Rep. No. NTSB-BA-71-3, Nat.

T r a n s p . S a f e t y B o a r d , Oct. 1 , 1 9 7 1 .

2 . H o l l i s t e r , Walter M . ; L a P o i n t e , A r t h u r ; Oman, C h a r l e s M . ; a n d R . : I d e n t i f y i n g a n d D e t e r m i n i n g S k i l l D e g r a d a t i o n s T o l e , J o h n of P r i v a t e a n d Commercial P i l o t s . FAA-RD-73-91, S e p t . 1 9 7 3 .

3. O ' B r y a n , T . C . ; G o o d e , M . W . ; a n d Harris, R . L . : A S t u d y o f L i g h t A i r p l a n e P i l o t L a n d i n g P e r f o r m a n c e . [ P r e p r i n t ] No. 7 4 0 3 5 0 , S O C . A u t o m o t . E n g . , A p r . 1 9 7 4 .

4 . 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 Cate- g o r y . F e d e r a l A v i a t i o n R e g u l a t i o n s , p t . 2 3 , FAA, J u n e 1 9 7 4 .

5. J e p p e s e n P r i v a t e P i l o t C o u r s e . J e p p e s e n T i m e s M i r r o r , c . 1 9 7 1 .

6 . S e c k e l , Edward: The L a n d i n g F l a r e : An A n a l y s i s o f F l i g h t - T e s t I n v e s t i g a t i o n . N A S A CR-2517, 1 9 7 5 .

7 . P r i v a t e P i l o t - A i r p l a n e . F l i g h t T e s t G u i d e [ P a r t 6 1 R e v i s e d ] , A C 6 1 - 5 4 , FAA, 1 9 7 3 .

8 . F l i g h t T r a i n i n g H a n d b o o k . A C 6 1 - 2 1 , FAA, 1 9 6 5 .

1 9 TABLE I.- LOW-WING AIRPLANE C H A R A C T E R I S T I C S [ A i r p l a n e O w n e r ' s Manual]

Wing a r e a , m2 ( f t 2 ) . . . . . . . . . . . . . . . . . 1 4 . 9 ( 1 6 0 )

Wing s p a n , m ( f t ) . . . . . . . . . . . . . . . . .

9 . 1 ( 3 0 ) L e n g t h , m ( f t ) . . . . . . . . . . . . . . . . . . .

7 . 2 ( 2 3 . 5 )

H e i g h t , m ( f t ) . . . . . . . . . . . . . . . . . . . 2 . 2 ( 7 . 3 )

P o w e r , k w ( h p ) . . . . . . . . . . . . . . . . . . . 134.3 ( 1 8 0 )

Empty w e i g h t , k g ( l b ) . . . . . . . . . . . . . . . .

5 9 1 ( 1 3 0 3 )

G r o s s w e i g h t , k g ( l b ) . . . . . . . . . . . . . . . . 1089 - ( 2 4 0 0 )

N o m i n a l t e s t w e i g h t , a k g ( l b ) . . . . . . . . . . . . 9 2 5 ( 2 0 4 0 ) N e v e r e x c e e d s p e e d , k n o t s (mph) . . . . . . . . . . .

1 4 9 ( 1 7 1 )

A p p r o a c h s p e e d f o r -

F l a p s u p , k n o t s (mph) . . . . . . . . . . . . . .

7 4 ( 8 5 ) F l a p s IOo, k n o t s ( m p h ) . . . . . . . . . . . . . .

71 ( 8 2 ) F l a p s 25O, k n o t s (mph) . . . . :. . . . . . . . .

6 9 ( 7 9 )

F l a p s 40°, k n o t s (mph) . . . . . . . . . . . . . . 6 6 ( 7 6 )

S t a l l s p e e d f o r -

F l a p s u p , g r o s s w e i g h t , p o w e r o f f , k n o t s ( m p h ) . .

F l a p s 40°, g r o s s w e i g h t , power o f f , k n o t s (mph) . .

T a k e - o f f g r o u n d r u n a t sea l e v e l f o r -

F l a p s 25O, g r o s s w e i g h t , maximum e f f o r t , m ( f t ) . . . . . . . . . . . . . . . . . . . . .

L a n d i n g g r o u n d r o l l a t sea l e v e l f o r -

G r o s s w e i g h t , m ( f t ) . . . . . . . . . . . . . . . 1 8 2 . 9 ( 6 0 0 )

S i n g l e e n g i n e F o u r p l a c e T r i c y c l e l a n d i n g g e a r ( f i x e d ) Basic metal c o n s t r u c t i o n F i x e d p i t c h p r o p e l l e r ~ . ~ .. . .- a N o t Handbook v a l u e .

TABLE 11.- H I G H - W I N G A I R P L A N E CHARACTERISTICS .

[ A i r p l a n e O w n e r ' s M a n u a l ]

. 16.2 ( 1 7 4 )

a r e a , m2 ( f t 2 ) . . . . . . . . . . . . . . .

Wing

Wing s p a n , m ( f t ) . . . . . . . . . . . . . . . . 1 1 ( 3 6 )

8.2 ( 2 7 ) < L e n g t h , m ( f t ) . . . . . . . . . . . . . . . . . .

. 2 . 7 ( 8 . 7 5 )

H e i g h t , m ( f t ) . . . . . . . . . . . . . . . . . .

. 1 1 1 . 9 ( 1 5 0 )

Power, kw ( h p ) . . . . . . . . . . . . . . . . . .

. 5 9 2 ( 1 3 0 5 )

Empty w e i g h t , k g ( l b ) . . . . . . . . . . . . . .

. 1 0 4 3 ( 2 3 0 0 )

Gross w e i g h t , k g ( l b ) . . . . . . . . . . . . . .

. 8 9 4 ( 1 9 7 0 )

N o m i n a l t e s t w e i g h t a , k g ( l b ) . . . . . . . . . .

Never e x c e e d s p e e d ( c a l i b r a t e d a i r s p e e d ) ,

k n o t s (mph) . . . . . . . . . . . . . . . . . . . 1 5 1 ( 1 7 4 )

A p p r o a c h s p e e d f o r -

7 0 ( 7 0 t o 8 0 )

F l a p s u p , k n o t s (mph) . . . . . . . . . . 6 1 t o

F l a p s down, k n o t s (mph) . . . . . . . . . 5 6 t o 65 ( 6 5 t o 7 5 )

S t a l l s p e e d f o r -

F l a p s u p , g r o s s w e i g h t , power o f f , a f t c . g . , c a l i b r a t e d a i r s p e e d ,

. . . 5 0 ( 5 7 )

k n o t s (mph) . . . . . . . . . . . . . . . . .

F l a p s 40°, g r o s s w e i g h t , power o f f , a f t c . g . , c a l i b r a t e d a i r s p e e d ,

k n o t s ( m p h ) . . . . . . . . . . . . . . . . . . . . . 4 3 ( 4 9 )

T a k e - o f f g r o u n d r u n a t sea l e v e l f o r -

. 2 6 3 . 7 ( 8 6 5 )

F l a p s u p , g r o s s w e i g h t , m ( f t ) . . . . . . . . .

L a n d i n g g r o u n d r o l l a t sea l e v e l f o r -

F l a p s 40°, g r o s s w e i g h t , m ( f t ) . . . . . . . . . 1 5 8 . 5 ( 5 2 0 )

S i n g l e e n g i n e F o u r p l a c e T r i c y c l e l a n d i n g g e a r ( f i x e d ) Basic metal c o n s t r u c t i o n F i x e d p i t c h p r o p e l l e r a N o t Handbook v a l u e .

TABLE 111.- TEST SUBJECTS ( a ) L o w - w i n g a i r p l a n e T o t a l f l i g h t N u m b e r o f N u m b e r o f P i l o t h o u r s a t L i c e n s e l a n d i n g s l a n d i n g s b e g i n n i n g h e l d m a d e o n m a d e o n of p r o g r a m l o n g r u n w a y s h o r t r u n w a y 1 P r i v a t e 2 0 115 18 2 P r i v a t e 1 8 300 18 P r i v a t e 2 2 3 8 7 18 --- 4 P r i v a t e 9 2 7 P r i v a t e 5 55 18 6 2 4 0 P r i v a t e 2 7 2 3 5 6 0 P r i v a t e 18 7 18 --- 8 S t u d e n t 3 0 1 3 --- 1 0 0 P r i v a t e 9 2 4 1 0 4 0 S t u d e n t 18 T o t a l 144 I . \ ... . . . - ( b ) H i g h - w i n g L r p i a n e T o t a l f l i g h t N u m b e r o f N u m b e r o f P i l o t h o u r s a t L i c e n s e l a n d i n g s l a n d i n g s b e g i n n i n g h e l d made o n m a d e o n o f p r o g r a m l o n g r u n w a y s h o r t r u n w a y 1 S t u d e n t 18 2 4 0 P r i v a t e 1 8 S t u d e n t 2 0 3 45 4 P r i v a t e 7 5 2 0 5 P r i v a t e 18 3 3 0 6 P r i v a t e 1 0 5 19 7 30 S t u d e n t 1 0 0 P r i v a t e 1 6 g o o t o 1000 Commercial 9 17 1 0 P r i v a t e 1 4 5 1 1 S t u d e n t 12 1 0 0 P r i v a t e T o t a l 1 6 3 1 5 4

I

1 V . - MEAN F I N A L A P P R O A C H A I R S P E E D A N D S T A N l j A I i D D E V I A T I O N T A B L E _ _ -

T i m e F i n a l a p p r o a c h a i r s p e e d , k n o t s , f o r -

. - - - _ _ - - .

b e f o r e Low-wing a i r p l a n e o n - H i g h - w i n g a i r p l a n e o n -

S h o r t r u n w a y ; o u c h d o w n , Lon; r u n w a y S h o r t r u n w a y _ _ ~- . .- -_____ Mean S t a n d a r d sec Mean S t a n d a r d Mean S t a n d a r d Mean ; t a n d a r d d e v i a t i o n d e v i a t i o n i e v i a t i o n l e v i a t i o n

8 3 . 6 - 8 . 9 8 5 . 3 6 0 8 . 4 8 . 0 67 .-6 6 . 6

77.0 8 1 . 3 8 4 . 6 6 8 . 6 6.8 ? . 7 55 7 . 2 77.4 7 . 6 84.8 8 0 . 3 50 6.6 7 7 . 8 7 . 6 6 7 . 8 7 . 2 9 . 3 11.5 83.8 6 . 8 8 . 2 66.9 77.6 45 7 7 . 8 7 . 2 7 6 . 4 8 3 . 0 40 6 . 2 8 . 2 66.7 9 . 7 77.4 7 . 4 67.1 7 5 . 4 9.1 81.6 5 . 6 7 7 . 0 8 . 0 7 . 4

7 4 . 6 (3 . 2 81.6 6 6 . 9

30 5 . 8 7 6 . 4 7 . 6 7 . 2 7 4 . 8 7 . 8 8 1 . 5 25 7 5 . 2 7 . 4 66.1 7 . 0 5 . 1 8 0 . 3 20 6 . 6 6 . 6 7 4 . 1 7 . 0 4 . 9 7 4 . 5 65.9 6 . 6 6 . 6 6 . 6 72.9 79.1 15 4 . 3 7 3 . 3 65.3 6 . 0 10 6 . 8 64.C 71 - 9 78.9 5 . 3 71.1 5 . 8 6 8 . 8 7 4 . 8 5 6 . 6 6 0 . 3 6.4 5.4 5 . 4 6 7 . 3 6 6 . 3 0 6 . 2 60.5 5 . 6 5 8 . 7 7 . 8 4 9 . 6 7 . 0 -- ~~

I

TABLE V . - D I S C R E P A N C I E S S C O R E D D U R I N G L A N D I N G S E x p l a n a t i o n D i s c r e p a n c y F l i g h t - p a t h d e v i a t i o n s C h a n g e s i n f l i g h t p a t h a n d / o r a i r s p e e d d u r i n g a p p r o a c h D e t e r m i n e d p r i m a r i l y b y p i t c h a t t i t u d e F a s t a p p r o a c h d u r i n g a p p r o a c h A i r p l a n e t o o h i g h when e n t e r i n g camera H i g h , s t e e p a p p r o a c h f i e l d o f v i e w - f l i g h t - p a t h a n g l e s t e e p F l a r e o c c u r r e d t o o h i g h a b o v e r u n w a y H i g h f l a r e More t h a n o n e f l a r e p r i o r t.o t o u c h d o w n M u l t i p l e f l a r e O v e r f l a r e A i r p l a n e p i t c h r o t a t i o n d u r i n g f l a r e t o o m u c h ; a i r c r a f t s t a r t s t o c l i m b A i r p l a n e p i t c h r o t a t i o n d u r i n g f l a r e Late f l a r e i n c o m p l e t e b e f o r e t o u c h d o w n No f l a r e No p i t c h r o t a t i o n b e f o r e t o u c h d o w n F l o a t E x c e s s i v e d i s t a n c e c o v e r e d a f t e r f l a r e a n d b e f o r e t o u c h d o w n A i r p l a n e p i t c h a t t i t u d e t o o l o w a t N o s e - l o w t o u c h d o w n t o u c h d o w n B o u n c e L a n d i n g g e a r c l e a r s r u n w a y a f t e r i n i t i a l c o n t a c t d u r i n g t o u c h d o w n 2 4 I I . ..

L-73-2025 F i g u r e 1. - T e s t a i r p l a n e s ’ .

0 0 " Flaps

. 0 46'Flaps ----- Zero error - I I 2 0 Recorded indicated airspeed, knots ( a ) Low-wing airplane.

Figure 2.- Airspeed calibration o f test airplanes.

120- 110-

100 -

2 90- c *- U 0)

X 80-

c .- U 0) + 0 0 " Flaps B 70- a c 4 8 Flaps .- , u ) ----- c Zero error

'z 6 0 -

50 -

40t

I I I I I I I I 30 4 0 5 0 6 0 70 80 90 100 I IO 120 Recorded indicated airspeed, knots ( b ) High-wing airplane.

Figure 2. Concluded.

L - 7 2 - 4 0 7 3 . 1 F i g u r e 3.- Ground-tracking system.

..

2 9 w L-70-3711.1 Figure 5.- A i r p o r t w i t h l o n g runway.

L-72-7318.1 Figure 6 . - A i r p o r t w i t h s h o r t runway.

Headwind 1 I I I I I I 278 90" 4 8 12 1 6 Wind speed, knots

\

240 a,

t o

Tailwind ( a ) Low-wing a i r p l a n e o n l o n g r u n w a y .

Tailwind ( b ) Low-wing a i r p l a n e o n s h o r t r u n w a y .

F i g u r e 7.- W i n d s m e a s u r e d a t t o u c h d o w n r e l a t i v e t o a c t i v e r u n w a y .

Headwind 0 0 90" 24\ 180' J o 0 Tai I wi n d ( c ) H i g h - w i n g a i r p l a n e o n l o n g r u n w a y .

Toilwind ( d ) H i g h - w i n g a i r p l a n e o n s h o r t r u n w a y .

F i g u r e 7.- C o n c l u d e d .

m Runway threshold Runway end

f t 50r

I

I

e 9 5 Percentile

I

-5 Percentile I

I

I

I

I

I

U

A

-300 -200 -100 0 I O 0 200 500 400 1500 1 6 0 0 m I I I I I I 4 11 I -800 -400 0 400 800 1200 *'. 5000 ft Threshold distance ( a > Low-wing a i r p l a n e on l o n g r u n w a y .

F i g u r e 8.- F i n a l a p p r o a c h t r a j e c t o r i e s .

Runway end - I

I

ft 150- -95 Percentile

I

- 40 . -Median

I

I - 5 Percentile

I

E 0, .-

I

I" - 5 0

I

I O

I

'-' Median touchdown - 0 Oh - I O m I I I I I I I I -400 0 400 800 I200 1600 2000 2400 f i ( b ) Low-wing airplane on short runway.

Figure 8.- Continued.

w wl m Runway threshold Runway end I I

ft 50r

95 Percentile

I -

p h~ 100-

i

K

I

E 0, .- P 50-

I

I 0- -300 -200 -100 0 I O 0 2 00 300 400 500 600 I500 1600 m 1 I I I I I I I 411 I -800 - 400 0 400 8 00 I200 I600 2000 5000 ft Threshold distance ( c ) High-wing airplane o n long runway.

Figure 8.- Continued.

Runway end Runway threshold B \ -95 Rrcentik c -5 Percentile 2 100:- 30- g : 9 1 0 , i -

P 20

50 -

' Refei

0 k I

- 200 -100 0 100 2 00 400 50 -300 I I I I 1 I I I I - 800 -400 0 400 8 00 I200 I600 2000 2400 ft Threshold distance ( d ) H i g h - w i n g a i r p l a n e o n s h o r t r u n w a y .

F i g u r e 8 . - C o n c l u d e d .

I oc v) c S I

$ 80

Q) Q.

.- L 6 C II Measured stall speed, O'flaps 7 Q) Measured stall speed, 40°f laps 3- E Q ) .

k

0 Long runway

0 Short runway Solid symbols denote speeds 5 knots greater than the reference speed ----- Long runway reference approach speed --- Short runway reference approach speed I I I I I I

6 0 50 4 0 30 20 I O 6

Time before touchdown, sec ( a > Low-wing a i r p l a n e on b o t h r u n w a y s .

F i g u r e 9 . - F i n a l a p p r o a c h a i r s p e e d a n d f l a p d e f l e c t i o n .

u) c E Measured stall speed, 4Pflaps I 20L 0 Long runway 0 Short runway Solid symbols denote speeds 5 knots greater than the reference speed

------ Long runway reference approach speed

--- Short runway reference approach speed n n cl

20 - n n n

f-l U U n fi n n n W 1 I I 1 1 1 1 60 50 40 30 20 I O 0 Time before touchdown ,sec ( b ) High-wing a i r p l a n e o n b o t h runways.

F i g u r e 9 . - C o n c l u d e d .

- 0 Long runway - 0 Short runway - - 9 0 - c 70- 60-

.g 5 0 -

3 L 40-

c $ 30- Q .F’ 20- - V 10- 5 - 2- 1 - - .5 - .2 Measured stall speeds Reference approach speeds Cf Flaps Long runway d I . _J 1 L.

40 5 0 60 70 8 0 90 Airspeed at touchdown, knots (a) Low-wing airplane on both runways.

Figure 10.- Cumulative distribution of airspeed at touchdown.

4 0 99.9 99.81 0 Long runway 0 Short runway - - - - - c 5 70- 60- .- 50- c =I e 40- L c . : 30- c 20- - 10- 5 - 2 - I - - .5 Reference approach speeds Measured stall speeds - .2 .'

- 4 o ' ~ Y Y F l a P s Shart runway Long runway I L

30 r . - m - 1 - 5b - I 60 P-. $0--- - ' 80

( b ) High-wing airplane on both runways.

Figure 10.- Concluded.

4 1 99.9-

99.8 -

-

0 Long runway

98 -

0 Short runway

-

-

80 -

70 -

60 -

50 -

-

30 -

20 -

-

I O 5 - Pitch attitude at touchdown,deg ( a > Low-wing a i r p l a n e o n b o t h r u n w a y s .

11.- C u m u l a t i v e d i s t r i b u t i o n o f p i t c h a t t i t u d e a t t o u c h d o w n .

99.9-

-

99.8

-

-

- 90.- - E 70- 0) 60- 50- .- c

3 40-

L .a-

.- < 30-

'= 20-

-

E'

0 I O - 5 - 2 - I -

-

.5

- Main-wheels

Nose-wheel

- c

- - landing landing 1 J I I I

f I I

( b ) H i g h - w i n g a i r p l a n e on b o t h r u n w a y s .

F i g u r e 1 1 . - C o n c l u d e d .

I m ------- ----- --- -95 Percentile Limits of trucking grid I I I I

gOl

I 5 Rrcentib a l I I 3 60- c ._ I + - I a I I I I 30- I I I I I I I 1 I I I 0 - 300 400 500 600 m -1000 -500 0 500 IO00 I500 2000 ft Threshold distance Figure 12.- Final approach trajectories of two selected landings including mean approaches o f individual pilots.

1 Measured stall speed,O0fIaps 7

40, -4 ' Measured stall speed,4O0flaps

i

20 1

0 Approach A 0 Approach 8 ----- Reference approach speed - approach A --- Reference approach speed -approach B I 1 I I I I I 60 50 40 30 20 I O 0 Time before touchdown,sec F i g u r e 13.- F i n a l a p p r o a c h a i r s p e e d a n d f l a p d e f l e c t i o n o f t w o s e l e c t e d i n d i v i d u a l l a n d i n g s .

4 5 Discrepancy High, steep approach Nose-low touchdown Flight-path deviations 0 20 40 60 80 I O 0 Percentage of landings (a) Low-wing airplane on long runway.

Figure 14.- Summary of qualitative evaluations.

4 6 Discrepancy Fast approach

I

Float

High, steep approach h \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ Y

Nose-low touchdown - - - I

Flight-path deviations I I I I I 0 20 40 60 80 I00 Percentage of landings ( b ) H i g h - w i n g a i r p l a n e o n l o n g r u n w a y .

F i g u r e 14.- C o n t i n u e d .

, 4 7 Discrepancy Fast approach Float High, steep approach

- i \ \ \ \ \ \ \ \ \ \

Nose-low touchdown Multiple flare

-

Flight- path deviations No flare

-

Bounce Over flare

-

Late flare

High flare - D

I I I I I I

0 20 40 60 80 I O 0 Percentage of landings ( c ) H i g h - w i n g a i r p l a n e on short r u n w a y .

F i g u r e 1 4 . - C o n c l u d e d .

L- 1 O 8 7 8 NASA-Langley, 1976 I I1111III IIII.III~I~III11111111111 II 1 1 1 1 1 1 1 II IIIIII I 111 11111 I I 1 1 1 1 I I I A motion-picture film supplement L-1208 is available on loan.

Requests will be filled in the order received.

The film ( 1 6 mm, 4.5 min, color, sound) shows various approaches and landings with delineated discrepancies noted during each approach and landing.

Requests for the film should be addressed to: NASA Langley Research Center Att: Photographic Branch, Mail Stop 425 Hampton, VA 23665

- - - - - - - - - - - - -CUT- - - - - - - - - - -

I I I Date-.._ . . - I _ _ - I I ;Please send, on loan, copy of film supplement li-1208 to NASA TN D-8283.

I I I I . . . . . - I Name of organization I I I I . . - _ _ _ - - ;Street number I I Zip code ;Attention: Mr. ~ _ _ ~ I I I I ~~ Title ~~ I I I P l a c e I I S t a m p I I I I I I I I I I I I I NASA L a n g l e y R e s e a r c h C e n t e r I A t t : P h o t o g r a p h i c B r a n c h , Mail S t o p 425 I I I Hampton, V A 23665 I I I I I I I I I I I I I I I I I I1 I I l 1 1 l 1 l 1 1 1 1 1 1 1 1 1 IIIIIII I1 Ill.

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