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

53 Pages·2002·2.16 MB·English

https://ntrs.nasa.gov/search.jsp?R=19770004090 2019-04-04T18:30:08+00:00Z
N A S A TECHNICAL NOTE,
M
00
N
O?
n
z
c
4
w
4
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 El. Mayo
Langley Research Center
Hanipton, Vu. 23665
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION WASHINGTON, 0. C. OCTOBER 1976
TECH LIBRARY KAFB, NM
1. Report No. I 2. Government Accession No. 11l#l1l1l1l1lI1111111111111111111111~1l11l1
NASA TN D-8283
~~~4~~~ . Title and Subtitle 013405b
LANDING PRACTICES OF GENERAL AVIATION PILOTS IN October 1976
SINGLE-ENGINE LIGHT AIRPLANES 6. Performing Organization Code
7. Author(s) 8. Performing Organization Report No.
Maxwell 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
NASA 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 available on request.
6. Abstract
The methods and techniques used by a group of general aviation pilots during
the landing phase of light airplane operations have been documented. This report
contains the results of 616 landings made by 22 pilots in 2 modern, four-place,
single-engine, light airplanes (one having a low wing and the other, a high wing).
The landings were made on both a long runway (1524 m (5000 ft)) and a short runway
(762 m (2500 ft)); both runways were considered typical of those used in general
aviation. The results generally show that most of the approaches were fast with
considerable floating during the flares and with touchdowns that were relatively
flat or nose-low.
7. Key-Words (Suggested by Authoris) ) 18. Distribution Statement
-
Light aircraft landing Unclassified Unlimited
Light aircraft pilot performance
9. Security Classif. (of this report) 20. Security Classif. (of this page) 21. No. of Pages 22. Price'
Unclassified Unc lass i f i ed 48 $3 75
-
LANDING PRACTICES OF GENERAL AVIATION PILOTS
I N SINGLE-ENGINE LIGHT AIRPLANES
Maxwell W. Goode, Thomas C. O'Bryan,
Kenneth R. Yenni, Robert L. Cannaday,
and Marna H. Mayo
Langley Research Center
SUMMARY
The methods and techniques used by a group of general aviation
p i l o t s during the landing phase of l i g h t airplane operations have
been documented. This report contains the r e s u l t s 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
airplanes (one having a low wing and the other, a high wing). The
land'ings were made on both a long runway (1524 m (5000 f t > >a nd a
short runway (762 m (2500 f t ) ) ; both runways were considered typi-
cal of those used i n general aviation. The r e s u l t s generally show
that most of the approaches were fast with considerable floating
during the flares and with touchdowns that were relatively flat or
nose-low.
INTRODUCTION
The National Aeronautics and Space Administration (NASA) has
undertaken a research program t o document methods and techniques
used by general aviation p i l o t s t o land airplanes. This effort was
prompted by the general aviation safety records included i n refer-
ence 1. These reports indicate t h a t most accidents under visual
f l i g h t rules (VFR) occur during t h e landing phase of single-engine,
l i g h t airplanes flown f o r pleasure. I n t h e vast majority of these
accidents, the p i l o t is the cause or a t least a contributing factor.
Many factors influence p i l o t performance t o varying degrees; some
of these factors are defined i n reference 2 with the degree of
influence for each factor.
For t h i s study, two modern, four-place, single-engine, l i g h t
airplanes (one having a low wing and the other, a high wing) were
leased from a fixed-base operator (FBO). A cadre of general avi-
ation p i l o t s with various backgrounds and experiences was provided
by the FBO t o perform a series of landings both on a long runway
(1524 m (5000 f t ) ) and a short runway (762 m (2500 f t ) ) . Approach
and landing data were collected f o r approximately 150 landings on
each runway f o r each airplane with ground-tracking and airborne
data systems. A summary of the r e s u l t s of t h i s landing progPam is
presented t o characterize typical private p i l o t performance during
the landing phase of f l i g h t i n daylight VFR conditions. Prelimi-
nary results for the low-wing airplane phase of t h i s program are
presented i n reference 3.
A motion-picture f i l m supplement has been prepared and is
available on loan. A request card form and a description of the
f i l m w i l l be founb at the back of t h i s report.
TEST EQUIPMENT
The airplanes used i n t h i s study (fig. 1) were chosen as being
representative of the most widely used airplanes i n general aviation
private flying. Both airplanes were leased from FBO and were used
i n h i s f l i g h t training and r e n t a l programs. The test vehicles were
single-engine, four-place airplanes with fixed t r i c y c l e landing gear.
One of the airplanes had a low wing and the other had a high wing.
The d e t a i l s and specifications for each airplane were obtained from
the respective airplane owner's manuals and are presented i n tables I
and 11. Other than wing location, there are several basic differ-
ences between the two airplanes: ( 1 ) the longitudinal control system
for the low-wing airplane used a stabilator, whereas t h e high-wing
airplane used a conventional fixed horizontal s t a b i l i z e r and eleva-
tor; (2) the low-wing airplane was equipped with rudder t r i m and t h e
2
high-wing one was not; and (3) the low-wing airplane had manually
operated f l a p s with four discrete s e t t i n g s (Oo, IOo, 25O, and 40°),
whereas the high-airplane had e l e c t r i c a l l y operated f l a p s with
i n f i n i t e s e t t i n g s between Oo and 40'.
The airplanes were instrumented t o measure and record 21 dif-
ferent f l i g h t parameters including airspeed, pitch a t t i t u d e , f l a p
position, and altitude. The instrumentation system cons-isted of
sensors located throughout the airplane, a signal conditioning
package, and a central tape recorder. I n the low-wing airplane,
the instrumentation package was located i n the baggage compartment;
i n the high-wing airplane, the package was located i n the rear pas-
senger compartment. The only modification t o the instrument panel
was the installation of control switches for the recording system;
these switches were centrally located i n the panel. The only obvi-
ous change i n the external appearance of the airplanes was the test
boom protruding from t h e left wing t i p . This boom was approximately
75 percent of the wing chord i n length and was installed t o measure
airspeed, angle of attack, and angle of sideslip. A weight was
added inside the right wing t i p t o counterbalance the weight of the
test boom. The complete airborne data system increased the basic
weight of the test airplane approximately 86.2 kg (190 l b ) .
The f l i g h t characteristics of both airplanes were investigated
by NASA research p i l o t s before and after the modifications f o r
instrumentation. The qualitative r e s u l t s of these tests indicated
that the installation of the instrument systems had negligible
effects on t h e handling characteristics of both airplanes. A i r -
speed calibrations were conducted t o correlate the p i l o t ' s indi-
cated airspeed with the recorded indicated airspeed as measured
by the test boom. The airspeed calibration curves for each air-
plane are presented i n figure 2. The recorded indicated airspeed
was chosen as the common basis for comparison; therefore, unless
otherwise stated, a l l airspeeds referred t o i n t h i s report are
expressed i n terms of the recorded indicated airspeed. I n addition,
the wings-level, power-off, stall speed range of each airplane was
documented f o r various f l a p settings. These tests were conducted
3
i n accordance with t h e procedures specified i n part 23.201 of t h e
Federal Aviation Regulations (ref. 4). The stall speeds used i n
the figures are t h e measured stall speeds of t h e respective air-
planes a t t h e nominal test weight, whereas t h e stall speeds i n
the tables reflect t h e manufacturers' specified values.
A ground-tracking system was used t o obtain t h e flight-path
data during-the f i n a l stages of t h e approaches and the touchdown
data. This system, shown i n figure 3, consisted of a 16-mm
motion-picture camera and a large photographic grid. The grid
was located p a r a l l e l t o t h e runway and between t h e camera and
the runway so t h a t both the airplane and portions of the grid
were photographed simultaneously during t h e f i n a l approach and
landing. The exact location of t h e system was surveyed with
respect t o t h e landing end of t h e runway. The grid consisted of
a series of v e r t i c a l and horizontal p l a s t i c s t r i p s fastened a t
the intersections t o form squeres with sides 0.6 m (2 f t ) i n
length. The t o t a l system consisted of ten 6.7-m-long (22-ft-
long) sections with r i g i d aluminum poles between each section.
The support poles were adjustable t o compensate f o r uneven t e r r a i n
and t o set t h e desired elevation of t h e grid. The overall grid
system was 3.05 m (IO f t ) high and 67.06 m (220 f t ) long.
Normal photogrammetric techniques were used t o obtain the
trajectory data from the f i l m . All measurements were based on
the positions of t h e t i p of t h e airplane nose and t h e vertical
t a i l with respect t o the position of the photographic grid seen
i n each picture frame. These measurements were converted t o the
a t t i t u d e of the airplane and the location of its center of gravity
with respect t o t h e runway threshold. For photographic analysis
purposes, a l l landings were assumed t o be on t h e center l i n e of the
runway. Errors resulting from t h i s assumption were found t o be
negligible f o r the purpose of t h i s study. A f i e l d survey of a
typical grid i n s t a l l a t i o n indicated a tracking accuracy within
k0.3 m (&I f t ) .
Wind direction and velocity at 3.05 m (IO f t ) and a t 9.14 m
(30 ft) above ground level were measured and recorded for each
4
I
landing. A portable weather s t a t i o n with wind detection equipment
was located near t h e runway for t h i s purpose. (See fig. 4.)
TEST SUBJECTS
A cadre of 22 p i l o t s selected by FBO and approved by NASA per-
formed the landings i n t h i s program. The test subjects' experience
and background ranged from student p i l o t s with 30 hours f l i g h t time
t o a commercial p i l o t with about 1000 hours f l i g h t time. A complete
list of the test subjects with experience, f l i g h t time, and number
of landings performed is presented i n table 111. A l l t h e subject's
were qualified t o operate t h e test airplane i n accordance with cur-
rent Federal Aviation Administration rules and regulations. .Ten of
the p i l o t s flew i n t h e low-wing airplane phase of t h e program and
12 flew i n the high-wing phase. The original i n t e n t was f o r each
p i l o t t o perform landings on both the long and short runways for
the phase of the program i n which he was involved; however, f o r
various reasons, t h i s i n t e n t w a s not completely m e t , as can be
noted, from table 111.
AIRPORTS AND RUNWAYS
The airports chosen f o r t h i s program were selected primarily
because they were considered representative of a i r p o r t s used by gen-
eral aviation p i l o t s , and secondly, because they had a clear area
adjacent t o t h e landing runway t o accommodate t h e ground-tracking
system.
The a i r p o r t chosen for t h e long-runway landings w a s a large
controlled f i e l d serving a metropolitan area. A photograph of t h i s
f i e l d (fig. 5) shows two, hard-surface runways (2-20 and 6-24).
A l l landings were made on runway 2-20 which was 1524 m (5000 f t )
long and 45.7 m (150 f t ) wide with significant clear areas leading
t o the thresholds. Field elevation was 12.5 m (41 f t ) . The airport
handled a significant amount of traffic, both c i v i l and military.
A t t i m e s the traffic was heavy; t h i s necessitated modifications of
5
the standard traffic patterns, usually an extended downwind with
a long straight-in f i n a l .
The short-runway airport was a small uncontrolled f i e l d serv-
ing a r u r a l area. The photograph of t h e f i e l d (fig. 6) shows a
single, hard-surface runway (18-36). A l l landings were made on
runway 18 which was 762 m (2500 f t ) long and 15.2 m (50 f t ) wide
with an elevation of 9.1 m (30 f t ) . The approach t o the runway
was over water with a tree l i n e approximately 402 m (1/4 mile)
from the threshold. The area between t h e tree l i n e and the
threshold was an open f i e l d under cultivation. The airport had
very l i g h t traffic; consequently, the test subjects could f l y
t h e pattern without interference.
TEST PROCEDURES
A l l t h e p i l o t s were briefed on t h e purpose of t h e study and
the operation of the equipment prior t o participating i n the pro-
gram. They were asked t o make normal landings based on t h e i r
training and experience. They were a l s o asked t o turn t h e airborne
data system on j u s t p r i o r t o or j u s t after turning onto t h e f i n a l
approach; however, the operation of the airplane and the piloting
techniques were left completely t o t h e discretion of t h e individual
pilot. Each p i l o t was scheduled t o make a maximum of s i x landings
i n any one day without p r i o r practice on t h a t day. This situation
was imposed t o minimize practice effects and t o obtain data f o r
each p i l o t under different wind conditions. If f o r some reason
the p i l o t f a i l e d t o turn the airborne data system on during some
of the landings, t h e maximum was extended t o cover s i x data land-
ings. I n order t o help a l l e v i a t e traffic congestion on the long
runway, touch-and-go landings with a significant ground r o l l were
permitted. These landings were permitted on the assumption t h a t
t h i s procedure would not significantly affect t h e normal landing
performances. A l l the landings on the short runway were completed
t o a f u l l stop.
6
RESULTS AND DISCUSSION
The r e s u l t s of t h i s landing performance study cover a t o t a l
of 616 landings made i n both airplanes at both runways. A t o t a l
of 299 landings were made i n t h e low-wing airplane (144 on the
long runway and 155 on the short runway) and 317 landings were
made i n the high-wing airplane (163 on t h e long runway and 154
on the short runway).
Flight Conditions
A l l landings were made essentially a t sea level with an
ambient temperature range from 21' C t o 32' C (70' F t o 90' F).
The wind conditions f o r each landing are presented i n figure 7.
The data were recorded a t the time of each landing r e l a t i v e t o
the active runway as measured at 3.05 m (10 f t ) above ground
level. These data are presented t o show t h a t the landings were
made with a wide range of wind conditions, including variable
winds that resulted i n some landings being made with a tail-wind
component. The short-runway airport was located a considerable
distance from the normal base of operations; consequently, it
was more d i f f i c u l t t o conduct tests there under favorable wind
conditions than it was a t the long runway which was the normal
base of operations. A s a result, more landings with a tail-wind
component were made at the short runway than a t t h e long runway.
The p i l o t s were informed of the wind conditions at the time, and
tests were continued only when the p i l o t s judged that the t a i l
winds did not adversely affect their landing performance.
Traffic Patterns
A l l the p i l o t s were familiar with the airport used for the
long-runway landings since it was t h e i r normal base of. operation.
The approaches were a l l Itleft-hand" traffic patterns and entry
was nominally 244 m (800 f t ) above ground level. Generally, the
7
patterns could be characterized as being standard (ref. 5). How-
ever, as mentioned previously, t h e a i r p o r t handled a significant
amount of traffic which occasionally necessitated modifying t h e
traffic pattern t o provide spacing between airplanes. These pat-
tern modifications occurred only about 10 percent of the time.
Most of t h e p i l o t s were unfamiliar with t h e a i r p o r t used for
the short-runway landings. The airport was uncontrolled, with an
insufficient volume of traffic t o affect t h e landing patterns t o
any significant degree. Most of the p i l o t s stated t h a t they based
t h e i r landing pattern geometry on experience i n judging distance
from the runway without specific reference t o ground features. The
traffic patterns were a l l left hand and entered a t t h e standard
244-m (800-ft) a l t i t u d e . It was noted t h a t the tree l i n e approxi-
mately 402 m (1/4 mile) from t h e threshold usually provided enough
turbulence t o s l i g h t l y upset the airplanes on f i n a l approach. How-
ever, some of t h e approaches were made inside t h e tree l i n e and
were not subjected t o the upset.
Trajectories
Profiles of t h e approach t r a j e c t o r i e s measured with the
ground-tracking system f o r a l l landings of both airplanes a t both
runways are presented i n figure 8. These profiles were obtained
from the airplane position data taken i n increments of about 67 m
(220 f t ) along the ground track of the f i n a l approach and touch-
down. The long-runway data were i n i t i a t e d approximately 305 m
(1000 f t ) before the runway threshold for both airplanes. The
short-runway data for t h e low-wing airplane were limited t o about
61 m (200 f t ) before the threshold because of a limited f i e l d of
view created by a group of trees. However, f o r t h e short-runway
landings with the high-wing airplane, the ground-tracking system
was relocated; thereby, a f i e l d of view out t o approximately 198 m
(650 f t ) before t h e threshold was provided. Shown i n figure 8 are
t h e median and the 5- t o 95-percentile spread of t h e data f o r the
height of the airplane a t the threshold and f o r t h e touchdown
8