Tunstall-Pedoe describes an approach involving the application of
age-specific mortality data to estimation of incapacitation among pilots. He
also observes that a nonfatal attack can be disabling, thus rendering the pilot
incapable of performing the coordinated activity required by flying (9).
Conversely, it is well known that many people have carried on normal activity
for some time while experiencing a heart attack. Keele found 30% of cases
studied to have continued normal activities while experiencing cardiac pain (5).

Utilizing the age distribution of known incapacitation over the 8 years of
the study to distribute the 13 cases per year of incapacitation estimated by
the 1975-77 FAA Autopsy Study yields the rates contained in Table 2.

Clearly, the older age groups experience higher rates and contribute more
to the total cardiovascular incapacitations expected in general aviation
annually. While estimates of incapacitation are subjective at best, these

findings emphasize, as have other studies, the need for special medical
scrutiny of older age groups.

It is important to recognize the relative importance of incapacitation to
accident causation. During the 8 years involved in this study, a total of
30,447 general aviation accidents occurred, of which 5,163 involved one or
more fatalities. All known causes of incapacitation amount to 92 cases for a
rate of 3 accidents per thousand and 15 accidents per thousand fatal accidents
due to incapacitation. Even based on the higher estimated incapacitation
rates contained in Table 2, recognized medical factors still only account for
2% of all fatal accidents. It is known from other studies that only half of
sudden death victims have overt disease. However, the impact of evolving
medical certification criteria should be closely monitored for adverse trends
since we also know that sudden death occurs about nine times more frequently
among the same age groups with overt cardiovascular disease (4). At present,
it seems likely that greater impact could be achieved by convincing airmen not
to fly when experiencing any symptoms which might affect performance.

SUMMARY

Accident rates for cardiovascular incapacitation are low compared to other
factors known to contribute to general aviation accidents. Older age groups
experience higher incapacitation rates and contribute more to the total
incapacitations expected in general aviation. Greater education efforts
concerning the importance of medical fitness in the aviation environment are
likely to be more productive in reducing medical factors involvement in
general aviation accidents than are stricter medical criteria.



60 +

50-59

40-49

30-39

20-29

Age

(4.9)

(2.9)

a

P (0)
t 1 1 ' i}
1 2 3 4 5

Cases Per Year

FIGURE 3. EXPECTED ANNUAL CARDIOVASCULAR INCAPACITATIONS

BY AGE GROUP



——

Table 2

Estimated Annual Rates of
Cardiovascular Incapacitation in General Aviation

Cardiovascular Incapacitation Expected

Estimated Mid-year Annualized Cardiovascular

Age Frequency Population Rate/100 ,000 Incapacitation
20-29 0 280 ,676 0 0
30-39 11.5 238 ,083 0.6 1.4
40-49 28.9 166 ,550 2.2 3.7
50-59 23.1 104 236 2.8 2.9
60 + 40.4 24,497 20.6 4.9
TOTAL 104.0 814 ,042 1.6 13.0



Tabl-~ *

General Aviation Aircraft Accidents
Involving Pilot Incapacitation (All Causes)

1975 - 1982
Total Fatal Known Accidents Involving Incapacitation
Year Accidents Accidents Total Fatal
1975 3,995 633 19 18
1976 4,018 658 4 2
1977 4,079 661 11 7
1978 4,216 719 1 8
1979 3,818 631 6 5
1980 3,590 618 13 i
1981 3,500 654 10 9
1982* 3,231 589 8 7
TOTAL 30,447 5,163 92 77

*Last year for which complete data are available.

Source: National Transportation Safety Board; Washington, D.C.



Rate Per 100,000

25r

Isr

lor

— I H 4 J
20-29 30-39 40-49 50-59 60 +

Age

FIGURE 2. ESTIMATED ANNUAL RATES OF COMPLETE CARDIOVASCULAR
INCAPACITATION IN GENERAL AVIATION BY AGE GROUP



Acknowledgment

Special thanks are extended to Ms. Leslie Downey and Ms. Theresa Mengers for
their assistance in review and preparation of this manuscript.



REFERENCES.

Aviation Toxicology Laboratory, FAA Civil Aeromedical Institute,
Statistics provided by, October 1986.

Booze CF, Pidkowicz JK, Davis AW, Bolding FA. Postmortem Coronary
Atherosclerosis Findings In General Aviation Accident Pilot Fatalities:
1975-77. Aviat. Space Environ. Med. January 1981, 24-7,

Chapman PJC, The Consequences of In-Flight Incapacitation In Civil
Aviation, Aviat. Space Environ, Med. June 1984, 497-500.

Kannel WB, McGee DL. Epidemiology Of Sudden Death: Insights From The

Framingham Study. In: Josephson, ME and Brest AN, eds. Sudden cardiac
deaths, F.A. Davis Co, PA, 1985: 93-104.

Keele KD. Pain Complaint Threshold in Relation to Pain of Cardiac
Infarction. Br Med J 1968; 1: 670-3.

Kulak LL, Wick RL, Billings CE. Epidemiological Study of In-Flight
Airline Pilot Incapacitation., Aerospace Med. June 1971, 670-2,

Lane JC. Risk of In-Flight Incapacitation of Airline Pilots. Aerospace
Med. December 1971; 319-21.

NTSB, Data provided by, April 1967 and January 1986,

Tunstall-Pedoe H. Risk of a Coronary Heart Attack in the Normal Population

and How it Might be Modified in Flyers. European Heart Journal; 1984,
5(Sup A), 43-9,



Rate Per

100,000
60
a (57.1)
a
“a”
15
10
5
0
20-29 30-39 40-49 50-59 60 +
Age

FIGURE 1. KNOWN CARDIOVASCULAR INCAPACITATION AMONG GENERAL
AVIATION PILOTS BY AGE GROUP 1975 - 1982



accounts for approximately 20% of all deaths due to cardiovascular disease.
Alcohol and drug involvement in general aviation accidents, while fluctuating
greatly over the years of the study, is currently found in 7.7% of accidents (1).

The implications of sudden complete, or even partial, incapacitation in
the general aviation environment are likely to be more ominous since it is
unlikely that a second qualified pilot would be on board, whereas incapac-
itation in the multi-crew commercial aviation environment has repeatedly been
shown to result in a low probability of accident outcome (3,6,7). Records
maintained by the NTSB show a total of 37 fatal general aviation accidents due
to incapacitation in the United States from 1959 to 1965; approximately 6
known cases per year (8). A breakdown of more recent NTSB data for all causes
of pilot incapacitation is provided in Table 1. From 1975 to 1982 the total
number of accidents where incapacitation was recognized equaled 92.
Thirty-six of these cases were due to cardiovascular conditions (approximately
5 per year). Alcohol and a variety of other reasons ranging from pesticide
poisoning to fire in the cockpit were cited as causes of incapacitation in the
other cases (8). These known cases of incapacitation are no doubt a conserv-
ative estimate of accidents involving incapacitation given that trauma, fire,
and inattention to detail mask medical factors involvement in some accidents.

Autopsy studies conducted by FAA have found an average of 5 cases per year
involving cardiovascular incapacitation with an autopsy rate of 38%, or 13
cases per year when extrapolated to the entire fatal general aviation accident
population (2). As in the Framingham follow-up and other general population
studies, this study also indicates a higher probability of cardiovascular
incapacitation with age (see Figure 1) (4). The overall likelihood of
complete cardiovascular incapacitation, based on extrapolated values, is 1.6
recognized cases per 100,000 airmen per year, or 0.037 cases per 100,000 hours
flown in general aviation (1 incapacitation per 2,683,629 hours flown), These
estimates, of course, assume an accident outcome for each case of
incapacitation, a reasonable assumption for the cases indentified in this
instance.

Chapman has documented a cardiovascular incapacitation rate resulting in
accident of 1 per 8,307,082,800 (0.000012 per 100,000 hours flown) from
International Air Transport Association data (3). We further reports this
rate to be at least 10 times better than is required by Airworthiness Criteria
(European Joint Airworthiness requirements and Federal Aviation Regulations)
for comparably vital aircraft systems. Obviously, the multi-crew environment
is much safer than general aviation by comparison.

Earlier FAA studies also indicate a prevalence of severe coronary artery
disease in some 5% of autopsied general aviation pilots in command for the
years 1975 through 1977 (4).

How many of these latter victims were either partially or completely
incapacitated by their disease is unknown from autopsy or other findings,
representing an important point to ponder.



SUDDEN IN-FLIGHT INCAPACITATION IN GENERAL AVIATION

INTRODUCTION

The subject of incapacitation involving a crewmember in the flight
environment has been of intense interest to the aviation medical community
since the early days of aviation, This interest and concern for the
possibility of sudden incapacitation have been the foundation for deve lopment
of medical standards and the subject of much controversy concerning the
implied dangers of allowing airmen with various medical problems to fly.
Incapacitation in the general aviation flight environment is a matter of
utmost concern to the Federal Aviation Administration (FAA) since the
likelihood of accident is greater due to a lack of redundant pilot skills in
most instances, This study of general aviation accident data was accomplished
to address those ongoing interests and concerns based upon the latest
information available.

MATERIALS AND METHODS

Review of the literature dealing with incapacitation was accomplished to
include so-called “complete” versus “partial or subtle" incapacitation in the
multi-crew airline environment as well as the usual single-crew general
aviation environment. Additionally, general aviation accident records
maintained by the FAA and the National Transportation Safety Board (NTSB) were
referenced to provide background and basis for the material developed. The
NTSB, of course, has the final responsibility for assigning the probable
causes of civil aviation accidents. The FAA's Office of Aviation Medicine
(OAM) is extensively involved in supporting the NTSB where possible, or when
called upon, in conducting medical and human factor investigation of aviation
accidents. The OAM is also interested in precrash and postcrash medical
findings to verify the appropriateness of medical standards and identify
environmental hazards to flight safety. Records maintained by the FAA have
been referenced dating back to 1975 for purposes of this study. Estimates of
the probability of sudden incapacitation and probability of accident given
incapacitation in general aviation were developed based on literature,
historical, and current FAA/NTSB findings.

RESULTS AND DISCUSSION

The definition of incapacitation may vary considerably based on the
interest and perspective of the observer, the population being studied, and
the likelihood of reporting. To be sure, any change in the ability of a
flight crew member to function appropriately, whether due to physiological or
psychological reasons, may be appropriately labeled incapacitation, This
definition includes all possible disease states, as well as other temporary
and traumatic causes of sudden incapacitation. Practically speaking, however,
the most probable causes of incapacitation, in terms of likelihood of subse-
quent discovery in general aviation, are cardiovascular/cerebrovascular,
alcohol, and drugs, Food poisoning and other gastrointestinal disorders,
while representing an important cause of incapacitation in studies of
multi-crew environments, are unlikely to be discovered in general aviation
should a fatal accident ensue, Clearly, the most important cause of sudden
incapacitation or death among those diseases likely to be discovered in
general aviation accidents is coronary heart disease. United States
population mortality data further suggest that cerebrovascular disease



Technical Report Documentation Page

| ‘V. Report No. 2. Goverament Accession No. 3, Recipient's Catalog No.

DOT/FAA/AM/87/7

4, Title and Subtitle 5. Report Date

SUDDEN IN-FLIGHT INCAPACITATION IN GENERAL August _1987

AVIATION 6. Performing Organizotion Code

|. Performing Organization Report No.

. 7, Author! s)

Charles F. Booze, Jr.

9. Performing Orgonizotion Nome ond Address 10. Work Unit No. (TRAIS)
. FAA Civil Aeromedical Institute

P.O. Box 25082 TI. Contract or Grant No.

Oklahoma City, Oklahoma 73125

13. Type of Report and Period Covered

12, Sponsoring Agency Name ond Address

Office of Aviation Medicine FINAL REPORT
Federal Aviation Administration

800 Independence Avenue, SW. 14. Sponsoring Agency Code
Washington, D.C. 20591 AAM-132

TS. Supplementary Notes

16. Abstract

Incapacitation in the general aviation flight environment is a matter of utmost
concern to the Federal Aviation Administration since the likelihood of accident
is greater due to a lack of redundant pilot skills in most instances. The

purpose of this study was to appraise the adequacy of medical standards in mini-
mizing the risk of sudden incapacitation.

This study considered NTSB data and postcrash medical data received by the
Medical Statistical Section of the Civil Aeromedical Institute (CAMI), Oklahoma
City, Oklahoma, during the time period from 1975 to the present and other related
literature to estimate the probability of incapacitation in general aviation.

Data for the years studied indicate that approximately 3 accidents per thousand
(15 per 1,000 fatal accidents) are known to result from the incapacitation of
the pilot for all causes. Results further suggest that the likelihood of
incapacitation increases with age.

The occurrence of incapacitation for obvious medical reasons is less than would
be expected based on general population morbidity/mortality data; however, the
. need for continued vigilance in certification and education regarding flying
with known or suspected medical problems is emphasized.

17. Key Words 18, Distribution Statement

Incapacitation Document is available to the public

Accidents through the National Technical

Cardiovascular Incapacitation Information Service, Springfield,
Virginia 22161

19. Seeurity Classil, (of this report) 20. Security Clossif. (of this page) FI. No. of Poges | 22. Price

Unclassified Unclassified 13
Form DOT F 1700.7 (8-72) Reproduction of completed poge cuthorized

a