While the number and rates of those being exposed to general aviation are in a constant state of flux, the amount of general aviation exposure is and has been increasing for decades. (http://www.faa.gov) Currently, the FAA reports all accident data in raw numeric form and per 100,000 flight hours. This reporting allows for tracking over time, some international comparisons, and direct comparisons of general aviation and commercial flight. However, comparison with other forms of transportation is more difficult because automobile, railroad and nautical travel tend to have more even risk throughout a trip than does flight. (http://www.ntsb.gov/default.htm) This problem is well recognized in the field of injury epidemiology and was outlined by Robertson in his text Injury Epidemiology on page 41: Aircraft usually crash during attempts to take off or land. In the same make and model of airplane, a person who flies the same number of hours over shorter distances is at greater risk per hour flown than when flying the same number of hours over longer distances. (1)
Number of Aircraft:
Below in Table 1 is a detailed listing of the estimated number of registered general aviation aircraft in the United States in 1999. The total was an incredible 208,114. Commercial Aviation was estimated to have only 5,325 aircraft in 1999 (source: http://api.hq.faa.gov/forca00/tabl-2.pdf), while there were 212,685,000 registered automobiles in the United States during the same year. (http://www.ntsb.gov/Surface/highway/highway.htm)
General Aviation Registered Aircraft in 1999 as adapted from 2001 Nall Report FAA data (http://www.aopa.org/asf/publications/01nall.pdf )
||Number for General Aviation Type
*Experimental is occasionally used interchangeably with homebuilt, however I also found statements on the FAA website stating that the two terms are not synonymous and that experimental aircraft are not categorized under general aviation
Number of Flight Hours:
The FAA tracks and compiles flight hours for all types and subtypes of aircraft. Table 2 and 3 below showed detailed exposure data from AEROSPACE FACTS AND FIGURES 2001/2002. A detailed breakdown by general aviation craft sub-type (Table 2) and primary use (Table 3) is shown. The FAA estimate of flight hours for general aviation for 2000 was 30.8 million. (http://www.aopa.org/asf/publications/01nall.pdf ) These numbers can be compared with a total of 13,900,000 flight hours in for commercial aviation (http://www.nasdac.faa.gov/bts/btsfrm41.html ) and a total of 2,767,363million miles of travel for automobiles in the United States in 2000. (http://www.ntsb.gov/Surface/highway/highway.htm )
Number of Accidents and Fatalities:
Accident data has been collected for aviation in the United States since 1938.
Statistics concerning the total number and cause of accidents for aviation often lags behind by a number of years, because a professional team of regional or federal FAA investigators carefully investigates all aviation accidents. (Nall) A federal team generally investigates commercial accidents, while a regional team more commonly investigates general aviation accidents. (Regional office) Graph 2, Graph 3 and Table 4, which contain summary accident statistics for general aviation, are listed below. These were taken from the 2001 Nall report. (http://www.aopa.org/asf/publications/01nall.pdf )
The most recent data is for 2000 and the original data source is the FAA.
Graph 2 and 3 and Table 4
As shown above, the United Stated general aviation accident rate was 5.96 per 100,000 flight hours in 2000 and the fatal accident rate was 1.11 per 100,000 flight hours. (http://www.aopa.org/asf/publications/01nall.pdf ) There were 593 general aviation fatalities during 30,975,000 flight hours in 2000. (http://www.bts.gov/publications/nts/html/table_general_aviation_profile.html This corresponds to a fatality rate of 1.91 per 100,000 flight hours. By comparison the US experienced 37,526 fatal automobile accidents and 41,945 fatalities over 2,767,363 million miles in 2000. This corresponds to a fatal accident rate of 1.5 per 100 million miles and a fatality rate of 1.51 per 100 million miles. (http://www.ntsb.gov/Surface/highway/highway.htm ) Commercial aviation (part 121) had 51 accidents in 2000 (http://www.bts.gov/publications/tsar/2000/chapter3/commercial_aviation_fig1.html ), 3 fatal accident in 2000 and 92 fatalities during that same year. (http://www.bts.gov/publications/tsar/2000/chapter1 ) This corresponds to an accident rate of 1.0 per 100,000 flight hours, a fatal accident rate of 0.022 per 100,000 flight hours and a fatality rate of 1.9 per 100,000 flight hours.
This data can be compared with FAA NTSB data reports for 1996In that year part 121 (airlines) had 32 accidents and 342 fatalities during a total of 13,188,000 hours of flight in 1996. This corresponds to an accident rate of 0.24 per 100,000 flight hours, an fatal accident rate of 0.026 per 100,000 flight hours and a fatality rate of 2.59 per 100,000 flight hours. In the same report the FAA reported that there were 1,906 accidents and 359 fatalities in 24,100,000 flight hours. This corresponds to an accident rate of 7.90 per 100,000 flight hours and a fatal accident rate of 1.49 per 100,000 and a fatality rate of 2.62 per 100,000 flight hours. Add 1996 Automobile data. (http://www.bts.gov/publications/nts/html/table_02_17.html ) These figures are summarized below in Table 5.
|From available 2000 data
||Commercial Aviation (per 100,000 flight hours)
(per 100,000 flight hours)
(per 100 million miles)
|Fatal Accident Rate
|From available 1996 data
|Fatal Accident Rate
||Unable to access
Accident Numbers for Experimental Aircraft:
The only data I was able to find directly addressing crash rates for Experimental Aircraft was through the EAA website. The source of this information should therefore be viewed with some caution. The EAA reports the following:Amateur-Built/Custom-Built aircraft have an accident rate less than one percentage point higher than the general aviation fleet. In fact, the accident rate for these aircraft is dropping. The total number of registered homebuilt aircraft is increasing by about 1,000 per year, while the total number of accidents has stayed virtually the same. Another good barometer of safety is insurance rates. Companies that insure both home-builts and production aircraft charge about the same rates for owners of either type of airplane. That indicates a similar level of risk.Source: http://www.eaa.org/education/learn.html#SAFE
Accident Numbers for Helicopters in the US (Helicopter Study):
Three detailed representations of the number and causes for helicopter crashes between 1990 and 2000 are given below in Tables 6 and 7 and Pie Chart 1. I have included the numbers for all aviation, part 91 and part 135 to help in analysis. Unfortunately no rates were given. Next three taken from https://www.nasdac.faa.gov/aviation_studies/ntsb_helicopter_accident_study/helicopter_accident_study.html
||General Aviation (FAR Part 91/103/129)
||Air Taxi/Commercial (FAR Part 135)
Accident Causes for General Aviation:
Four main categories of accident causes are pilot-related, mechanical/maintenance, other and unknown. In 1998, 80% of accidents were attributed to pilot-related causes, 16% to mechanical/maintenance, 2% to other and 2% to unknown. Pilot-related causes can be further subcategorized. The 2001 Nall report for 1999 and 2000 pilot-related causes is listed below.
A breakdown of accidents in general aviation by operation type is presented below in Table 8 from the 2001 Nall Report. A breakdown of pilot-related causes from the 2001 Nall Report is presented subsequently in Graph 4.
Mechanical/Maintenance causes are broken down in the following distribution: 70% Engine/Propeller, 15% Gears/Brake, 5% Oil system, 2% Controls/Airframe, 3% Fuel System, 3% Electrical/Ignition, and 2% Vacuum System/Instruments. Weather- related causes are attributed to pilot-error.
Distributions of weather-related causes in table and graph format can be access at the following links: (These links are all part of the FAA Weather Study.)
Over 22% of accidents between 1989 and 1999 were weather related. Generally this data shows that the majority of these had no record of a weather briefing. Having received a weather briefing from a Flight Service Station was a close second. Other weather briefing sources made up a minority of reports. Over 62% were related to wind and over 35% to visibility/ceiling problems. Examples of visibility/ceiling problems are fog, haze/smoke, low ceiling, obscuration, clouds and sand or dust storms. Over 70% of weather related accidents occurred during personal use type flying. Overall the number of weather-related accidents is decreasing, but the proportion of accidents attributable to weather is staying relatively constant.