Safety Study

Public Aircraft Safety

NTSB Number SS-01/01
NTIS Number PB2001-917004

Abstract: Section 702 of Public Law 106181, the Wendell H. Ford Aviation Investment and Reform Act for the 21st Century, directed the National Transportation Safety Board to "conduct a study to compare the safety of public aircraft and civil aircraft," and to review safety statistics on aircraft operations since 1993. "Public aircraft" refers to certain government aircraft operations. Public aircraft status means, among other things, that an aircraft will not be subject to some of the regulatory requirements applicable to "civil" (or civilian) aircraft. Although the precise statutory definition has changed over the years, public aircraft operations generally include law enforcement, low-level observation, aerial application, firefighting, search and rescue, biological or geological resource management, and aeronautical research.

For this study, the Safety Board identified 341 public aircraft accidents that occurred during the years 19932000. Using activity data from the Federal Aviation Administration (FAA) (for the period 19961999), the Board calculated an accident rate of 3.66 accidents per 100,000 flight hours for nonmilitary, nonintelligence public aircraft. Using activity data from the General Services Administration (also for the period 19961999), the Board calculated an accident rate of 4.58 per 100,000 flight hours for nonmilitary, nonintelligence Federal aircraft. Both rates were lower than the general aviation accident rate (7.2 accidents per 100,000 flight hours), but higher than the accident rate for air taxis (3.47), scheduled 14 CFR Part 135 operations (1.06), or 14 CFR Part 121 operations (0.30). Comparisons between public and general aviation accidents revealed similar proportions of broad causal factors. However, accidents in these two sectors differed in other ways. A higher proportion of public aircraft crashed during local flights, at off-airport locations, and during maneuvering phases of flight. Also, accident-involved public aircraft pilots were more likely than accident-involved general aviation pilots to hold advanced ratings.

Limitations and flaws associated with the FAA's nonairline activity estimates made it impossible for the Safety Board to make carefully controlled comparisons of the safety of public versus civil aircraft. The data were not sufficiently detailed to support the calculation of public and civil aircraft accident rates for specific purposes of flight (for example, aerial observation, aerial application, and so on). Furthermore, FAA flight hour estimates are potentially biased because they are based on a survey that is administered to a sample of aircraft owners listed in the FAA's Civil Aircraft Registry, which is known to contain many outdated or inaccurate records.

As a result of this study, the Safety Board issued eight safety recommendations to the Federal Aviation Administration and two safety recommendations to the General Services Administration.