cent of pilots under each heading. The number
in parenthesis is the average number of hours
flown.

When the midair accident group was com-

TABLE VI

ACCIDENT AIRMEN FLIGHT TIME
LAST SIX MONTHS

pared Nie ane nonaceident group, od midair cc orowns: [ s-sowrs- | sttoo ness [tor nes & uP
group own significantly more. ere was 17:8 3% 1) 20% (38) 5% (100) 40% (204)
TABLE WW 30-39 2% (5) | 36% (31) | 6% (93) | 29% (304)
VISUAL CORRECTIONS: bed Wee) atm (au) | 2% (| 2a (326)
s 5058 29% (9) | 28% (35) | 14% (85) | 26% (293)
NON-ACCIDENT AIRMEN conove | 2m 10 | 20% 95) | sow (04 .
CORRECTIONS” “U1 AVERAGE NO. HRS. FLOWN
NOE OSTANT ‘WEAR ‘NEAR /DISTANT ‘HOME
me wm . 1% ah TABLE VII
3039 1% - TM% mu
40-49 5% 23% 5% 6% MID-AIR COLLISION
50-59 TM 26% 60% Mm AIRMEN FLIGHT TIME
sokove | - a bala - LAST SIX MONTHS- 1970-1973
"FAA RECORDS: ME 0-10 HRS* ‘11-50 HRS” ‘51-100 HRS* YOU HRS & UP
1729 25% (4) | 20% (28) | 15% (67) | 40% [429]
0-39 20% (3) | 15% (29) | 21% (90) 44% (323)
TABLE Iv 40-49 28% 15} | 29% (37) | 6% (65) | 37% (340)
50-59 10% (2) | 37% (31) | 16% (85) | 37% (425)
VISUAL CORRECTIONS soxover | 20% (10) | 20% (40) | 20% (60) | 40% (225)
ACCIDENT AIRMEN
(L| AVERAGE WO, HRS. FLOWW
CORRECTIONS* . . . . . .
ME STANT WEAR WEAR STANT 3 no significant difference in total flight time be-
1728 1% 15% 8% tween the three groups.
30-39 Bh - &% TM% Since it appears that visual corrections had no
40-49 a% 1% 28% 4% effect on midair collisions and the pilots involved
50-59 T% 36% 50% TM had flown more in the last 6 months than the
60. OVER = bad 80% = nonaccident pilots, the question arose as to pilot
us fatigue contributing to the midair accidents. To
try to get some indication as to whether this was
the case, the amount of flight time on the flight
TABLEV that the accident occurred was reviewed. The
NON-ACCIDENT AIRMEN FLIGHT TIME average flight time prior to the collision was 45
LAST SIX MONTHS minutes. However, this varied from take-off to
over 7 hours. Sixty percent of these pilots on
AE oxo wns: | isons: | st-tooMRs” | ror Rs & UP the fateful flight had been airborne 30 minutes
1729 50% (3) | 25% (24) 5% (60) 2% (400) or less. In fact 33% had been up only 10 min-
30-39 29% (4) | 39% (32) 6% (100) | 26% (417) utes or less. Eighty percent had been up one
40-49 ame ty | 19% (31) 1% (83) 28% (334) hour or less. Only 6% had been flying longer
50-59 14% (1) | 43% (33) 14% (70) 29% (290) than 2 hours (see Table VIII).
60 & OVER 20% (2) | 80% (15) - 20% (130) From these results, it would appear that fa-
tigue was not a major factor in the collisions,

|) AVERAGE NO. HRS. FLOWN

at least fatigue from the flights that the acci-





Figure 2 shows that the accidents occurred
generally throughout the year, for this four-year
period, with the exception of March, April and
May. Only 8% of the accidents occurred during
this three-month period.

The fatal midair collisions occurred in 27
states (see Figure 3).

Tables II, III, and IV depict visual correc-
tions for pilots. Table II shows pilots involved
in midair collisions, Table III shows nonaccident
pilots and Table IV shows accident pilots. As

FATAL MID-AIR COLLISIONS

1970-1973

© Fy

st 4
gal 4
ae
i“) |
Sap 1

oh 6 . 7

‘ [ 2 Cl

AM. PM. DUSK DAWN NIGHT
‘TIME OF DAY

Ficure 1. Percent of fatal midair collisions occurring
at different times of day.

FATAL MID-AIR COLLISIONS
1970-1973

1% OF MI-AR COLLISIONS
a

le clOlalh

wont

Ficure 2. Percent of fatal midair collisions occurring
in each month.

FATAL MID-AIR COLLISIONS
1970-1973

Ficure 3. States in which fatal midair collisions
occurred,

TABLE ll
VISUAL CORRECTIONS:
PILOTS IN MID-AIR COLLISIONS

CORRECTIONS ~
AGE DISTANT WEAR WEAR /DISTANT NONE
17:29 5% - 6% 89%
30-39 6% - 18% 78%
4049 % 4% M% 69%
50-53 - 1% 61% 229
60 & OVER - 20% 80% -
“FAA RECORDS

expected, in all three groups the nonaccident,
the accident and pilots involved in midair colli-
sions, most visual corrections occurred in pilots
40 years of age or more. However, 62% of the
pilots involved in midair collisions had no visual
corrections. Fifty-four percent of the nonacci-
dent pilots had no visual corrections as did 51%
of the pilots involved in other types of accidents.
From this, it appears that visual corrections
were not a factor in the midair accidents. In
fact, it appears that the pilots involved in mid-
air collisions had fewer visual corrections than
the other two groups.

The recency of flight experience was also
examined. Tables V, VI, and VII show the
flight time for the last six months with the per-



TABLE VIL
LENGTH OF FLIGHT PRIOR TO
MID-AIR COLLISION’

fiowmures on tess] ao mmures | sso mmures | si-t2ommures |t21 manuTES & ABOVE

33% (6) 27% (23) 20% (48) 14% (68) 6% (231)

“4 PERCENT OF ACCIDENTS THAT OCCURRED WITHIN THIS TIME PERIOO.
(1 = AVERAGE MO. OF MINUTES I FLIGHT PRIOR TO ACCIDENT.

dents occurred. However, this does not eliminate
the possibility of the pilot being fatigued prior
to take-off.

Ill. SUMMARY

Records of airmen involved in fatal midair
collisions from 1970 through 1973 were examined
and compared with two other groups of pilots:

(1) pilots involved in other types of accidents,
and (2) pilots without any accident records.
There is nothing in the results to indicate that
the pilots with visual corrections are a greater
risk. In fact, the pilots involved in midair col-
lisions as a group were better off visually.

The analysis of the pilot’s flight time for the
last six months, showed that pilots involved in
midair accidents had flown the greater number
of hours than the pilots in the nonaccident
group. There was no significant difference in
other accident pilot group.

There was no significant difference in total
flight time in the three groups.

It can be concluded from the results of this
study that visual impairment if corrected in ac-
cordance with out present medical standards,
does not constitute a midair collision risk for
USS. civil aviation pilots.


Technical Report Documentation Page

Report No. 2. Government Accession No. 3.

FAA-AM-75-5

. Recipient's Cotalog No.

, Title and Subtitle 5.

TO SEE OR NOT TO SEE: VISUAL ACUITY OF PILOTS

. Report Date

INVOLVED IN MIDAIR COLLISIONS 6

- Author's) Teonard C. Ryan, S.J. Gerathewohl,
Stanley R. Mohler, and Charles F. Booze, Jr.

~ Performing Organization Code

fe.

AAM-110

Performing Organization Report No.

}. Performing Organization Name ond Address
Aeromedical Applications Division

. Work Unit No. (TRAIS)

Research Planning Branch
Federal Aviation Administration

> Contract or Grant No.

Washington D.C. 20591

|. Sponsoring Agency Name and Address
Office of Aviation Medicine
Federal Aviation Administration

Type of Report and Period Covered

OAM Report

800 Independence Avenue, S.W.
Washington, D.C. 20591

Sponsoring Agency Code

. Supplementary Notes

. Abstract

The Medical records of airmen involved in midair collisions from 1970

through 1973 were reviewed and compared with two other
(1) pilots involved in other types of accidents ,
any accident records. There is nothing in the results

the pilots with visual corrections are a greater risk.

and (2) pilots without

groups of pilots:

to indicate that

Key Words

Midair Collision
Aircraft Accidents

18, Distribution Statement

Document is available to the public
through the National Technical Informatio)

Visual Service, Springfield, Virginia 22151
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TO SEE OR NOT TO SEE: VISUAL ACUITY OF PILOTS
INVOLVED IN MIDAIR COLLISIONS

I, INTRODUCTION

Midair collisions remain an area of great
concern in aviation safety. Midair collisions are
unlike other types of aircraft accidents, in that
jn almost 50% of all cases, there is at least one
death.

Various methods and techniques have been
tried and some are presently in use to enable the
pilot to avoid the potential midair collision.
Various studies have been performed on visual
collision avoidance techniques. New and dif-
ferent lighting systems have been tested. The
Federal Aviation Administration, Department
of Transportation, adopted new rules requiring
all powered U.S. civil aircraft with a standard
airworthiness certificate to be equipped with ap-
proved anticollision lights for night operations
after August 11, 1972, as an aid in preventing
midair collisions. With the sky becoming more
and more crowded and aircraft flying at higher
speeds, it is conceivable that the problem of pre-
venting midair collisions will be worse in the
future. The most often probable cause of the
midair collision cited by the National Transpor-
tation Safety Board is “pilot in command failed
to see and avoid other aircraft.” From the
above, one can begin to realize the importance
of vision in avoiding a collision in the see-and-
be-seen system.

In order to answer the question of whether
there is a correlation between visual acuity and
midair collision, all available medical records of
US. civil pilots involved in fatal midair colli-
sions from 1970 through 1973 were reviewed and
analyzed as to visual functions, impairments and
corrections as to visual acuity and compared with
two groups of pilots: (1) Pilots who had no
aircraft accidents, and (2) pilots involved in
other types of aircraft accidents.

Since we were unable to study all of the pilots
involved in other types of accidents and all of
the pilots who had no aircraft accidents, it was
desirous to select representative samples from
these two groups. For this reason, random
samples were selected using systematic sampling
techniques. If the airman’s medical record
stated that he needed glasses for near, distant,
or near and distant vision, the pilot was placed
in the visual correction group. No consideration
was given to the degree of visual impairment.

Il RESULTS AND DISCUSSION

Table I shows there were 118 midair collisions
from 1970 through 1973. At least one fatality
occurred in 66 of these accidents. There were
221 fatalities in all and 28 serious injuries.

These midair collisions occurred generally dur-
ing daylight hours. Figure I depicts the percent.
of accidents that occurred at various times of
day. . Fifty-six percent of the accidents occurred
in the afternoon, 32% in the morning, with the
remaining 12% occurring at night, dusk and
dawn. Most occurred in weather conditions
when the visibility was acceptable (3 miles or
more).

TABLE I
MID-AIR ACCIDENTS - INJURIES
U.S. CIVIL AVIATION: 1970-1973"

FATAL ‘SEROUS,
ACCIOONTS MCIDENTS FATALITES URES
18 66 ma 2B
“NTS RECORDS