Work-Related Aviation Fatalities -- Alaska, 1990-1994

During 1990-1994, the annual occupational fatality rate in Alaska was 29.1 deaths per 100,000 workers, nearly six times the annual rate for the United States (5.1 per 100,000). In the United States, aviation-related fatality is the seventh leading cause of fatal occupational injury (1); however, in Alaska, this category is the second leading cause of occupational death. To characterize occupational aviation fatalities in Alaska, CDC analyzed all fatal occupational aviation crashes in Alaska during 1990-1994 (the most recent year for which complete data were available) and compared findings with overall patterns for the United States. This report summarizes the results of that study, which indicate that workers in Alaska are at increased risk for being killed in aircraft crashes when compared with all U.S. workers.

For all aircraft crashes during the study period, National Transportation Safety Board (NTSB) Accident Briefs were abstracted to obtain information about flight purpose, weather, aircraft, pilot, and probable cause. These reports were merged with records from the Alaska Occupational Injury Surveillance System, a database established and maintained by CDC's National Institute for Occupational Safety and Health, which includes information about cause of death, occupation of decedent, and circumstances associated with the crash. This study includes all occupational deaths related to commercial, military, and general aviation (i.e., all flying not involving military aircraft, scheduled airlines, and commuter or air-taxi service). For this analysis, an aircraft crash was defined as an incident in Alaska in which an aircraft in motion sustained substantial damage or an incident that resulted in injury or death to an aircraft occupant. An aircraft crash was categorized as occupational if at least one of the occupants in the aircraft was 1) working for pay or compensation; 2) working as a volunteer emergency medical technician, firefighter, or law enforcement officer; 3) traveling on business, including to and from customer/business contacts; or 4) engaging in a work activity in which the aircraft is the work environment. Denominator data for rates were based on 1990 U.S. Bureau of the Census and Alaska Department of Labor estimates.

During 1990-1994, a total of 876 aircraft crashes occurred in Alaska; of these, 405 (46%) were occupational. Overall, 106 (12%) crashes resulted in at least one fatality, and 69 (65%) of these were classified as occupational. Of these, 62 (90%) involved fixed-wing aircraft, and seven (10%) involved helicopters. Nearly all (61 {98%}) of the fixed-wing crashes involved propeller-driven aircraft; 54 (89%) were single-engine aircraft. No occupational fatalities occurred on scheduled commercial airline operations.

A total of 192 occupants were on board the 69 aircraft involved in the fatal occupational crashes; 149 (78%) of these occupants were killed. Of the 149 fatalities, 99 (66%) were occupation-related. The annual occupational fatality rate for pilots in Alaska was 268 per 100,000, 2.1 times higher than the U.S. pilot-specific rate of 126 per 100,000 (1). For all workers in Alaska, regardless of occupation, the death rate for work-related aircraft crashes was 8.3 per 100,000, 27.1 times higher than the U.S. rate of 0.3 per 100,000 (1).

The mean number of persons on board the aircraft was 2.8 (range: one-11); in 23 (33%) of these crashes, only the pilot was on board at the time of the crash. The mean age of the occupational decedents was 39 years (range: 20-68 years), and most (58 {59%}) were aged 30-44 years. In addition, nearly all (96 {97%}) deaths occurred among men. The most common cause of death was multiple impact injuries (48 {48%}), followed by head injuries (27 {27%}) and injuries to the chest (11 {11%}).

The takeoff and landing phases of flight together accounted for 228 (56%) occupational crashes, but for only eight (12%) of the fatal occupational crashes. Most (137 {60%}) of these crashes were associated with unimproved, off-airport sites (e.g., sandbars, mountain ridges, and meadows). Controlled flight into terrain during the cruise phase of flight (i.e., straight and level flying) or the maneuvering phase of flight (i.e., changing altitude or direction) together accounted for 46 (67%) fatal occupational crashes. The most common (28 {41%}) impact sites of fatal crashes were mountain sides and passes.

The Federal Aviation Administration (FAA) defines two categories of flying conditions based on meteorologic considerations. Instrument Meteorological Conditions (IMC) exist when visibility is less than 1 mile or the aircraft cannot be operated clear of clouds or overcast; in IMC, pilots must rely on instrumentation for navigation. Visual Meteorological Conditions (VMC) exist when visibility is greater than or equal to 1 mile and pilots can use visual cues for navigation. In Alaska, crashes occurring under IMC were 5.3 times (95% confidence interval=3.5-7.9) more likely to be associated with a death than crashes in VMC.

NTSB determined that pilot error (defined as aircrew action or inaction that became a contributing cause or factor in the crash) was a cause in 53 (77%) of the fatal occupational aviation crashes in Alaska. In addition, 23 (33%) of the aircraft involved in fatal occupational incidents were not completely destroyed; however, only 22% of the occupants of these aircraft survived.

Reported by: Alaska Field Station, Div of Safety Research, National Institute for Occupational Safety and Health, CDC.

Editorial Note

Editorial Note: When compared with risks for all U.S. workers, occupational aviation fatalities among workers in Alaska accounted for a disproportionate number of occupational fatalities in that state: workers in Alaska were 27 times more likely to be killed in an aircraft than were all U.S. workers. This increased risk reflects, in part, the greater use of aircraft for routine transportation in Alaska. Controlled flight into terrain during the transition from VMC to IMC was the most frequently identified cause of occupational crashes. This transition is a difficult flight task for pilots, and FAA regulations prohibit pilots of single-engine aircraft from flying in IMC while carrying passengers for compensation.

In Alaska, many pilots risk flying into potentially hazardous conditions because of the demand for reliable air service. In 1994, 70% of pilots in Alaska involved in the commuter and air-taxi industry reported inherent pressures in their flight operations, including self-induced pressures, mail-delivery responsibilities, and pressures from passengers, management, and other pilots (2). Approximately half of pilots surveyed reported having flown from VMC into IMC on at least one occasion, and 84% reported having inadvertently entered IMC on a VMC flight. Weather conditions in Alaska can change rapidly, and the vast distances between some weather reporting points often conceal substantial local variation in the weather. However, VMC flight into IMC usually involved poor pilot decision making (3).

The frequency of pilot error in the incidents described in this report underscores the need for the development and introduction of Alaska-specific Aeronautical Decision Making (ADM) and judgement training (3). ADM is designed to assist pilots in making better decisions during potentially hazardous conditions, to avoid situations that require skill beyond their capabilities, and to reduce the number of judgement-related crashes. The FAA has proposed requiring ADM training for all levels of pilot certification in the United States (4).

NTSB has recommended that all pilots use protective equipment to reduce aviation fatalities (5). Helmets, energy-absorbing structures, padding the occupant's immediate environment, and use of shoulder restraints could reduce the number of aircraft-related occupational fatalities (5,6).

This analysis produced a descriptive characterization of the epidemiology of occupational aviation fatalities in Alaska. Additional efforts will be required to assess the association between other potential risk factors (e.g., carbon monoxide exposure, aging aircraft, pilot fatigue, and risk-taking) and occupational aviation fatalities. One important limitation of this analysis was the lack of accurate and reliable denominator data to control for exposure (i.e., flight hours). Fatal aircraft incident rates provided by the NTSB generally are presented as fatal incidents per 100,000 aircraft flight hours; however, these rates are based on national estimates, and these estimates cannot be applied to occupational aviation in Alaska.

In response to this study, the Alaska Interagency Working Group for the Prevention of Occupational Injuries has formed an aviation working group (including representatives from industry and state and federal agencies), to determine strategies for reducing such crashes. Ongoing activities include data collection and dissemination of information to local news media, industry, and educational and flight-safety organizations in Alaska.

References

1. Toscano G, Windau J. Compensation and working conditions. Washington, DC: Bureau of Labor Statistics, National Census of Fatal Occupational Injuries, 1995.

2. National Transportation Safety Board. Aviation safety in Alaska: safety study. Washington, DC: National Transportation Safety Board, 1995; document no. NTSB/SS-95/03.

3. National Transportation Safety Board. Safety recommendation. Washington, DC: National Transportation Safety Board, 1995; document no. A-95-121-136.

4. Federal Aviation Administration. Notice of proposed rule-making: 95-11, human factors and aeronautical decision making. Part 61 B, Human Factors (paragraph 28) and ADM (paragraph 29). Federal Register 1995;60:41160.

5. National Transportation Safety Board. General aviation crashworthiness project: impact severity and potential injury prevention in general aviation accidents. Springfield, Virginia: National Technical Information Service, 1985; document no. NTSB/SR-85/01.

6. Desjardins SF, Laananen DH, Singley GT. Aircraft crash survival design guide: design criteria and checklist. Vols 1-4. Springfield, Virginia: National Technical Information Service, 1980; document no. AD-A093784.

   
   

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