NATIONAL

TRANSPORTATION

SAFETY BOARD

WASHINGTON, D.C. 20594

SAFETY STUDY

PB2001-917004

NTSB/SS-01/01

Public Aircraft Safety

7393

Safety Study

Public Aircraft Safety

NTSB/SS-0101

PB2001-917004 National Transportation Safety Board

Notation 7393 490 LíEnfant Plaza, S.W.

Adopted October 23, 2001 Washington, D.C. 20594
National Transportation Safety Board. Public Aircraft Safety. Safety Study NTSB/SS-01/01.

Washington, DC: NTSB, 2001.

Abstract: ìPublic aircraftî are aircraft operated for the purpose of fulfilling a government function that

meet certain conditions specified under Title 49 United States Code, Section 40102(a)(37). The Safety

Board identified 341 public aircraft accidents that occurred during the years 1993ñ2000. Using activity

data from the Federal Aviation Administration (FAA) (for the period 1996ñ1999), 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 1996ñ1999), 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 Part 14 CFR 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 FAAís nonairline activity estimates made it impossible for the 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 FAAís

Civil Aircraft Registry, which is known to contain many outdated or inaccurate records. As a result of these

findings, the Board made safety recommendations to the Federal Aviation Administration and the General

Services Administration.

The National Transportation Safety Board is an independent Federal agency dedicated to promoting aviation, railroad, highway, marine,

pipeline, and hazardous materials safety. Established in 1967, the agency is mandated by Congress through the Independent Safety Board

Act of 1974 to investigate transportation accidents, determine the probable causes of the accidents, issue safety recommendations, study

transportation safety issues, and evaluate the safety effectiveness of government agencies involved in transportation. The Safety Board

makes public its actions and decisions through accident reports, safety studies, special investigation reports, safety recommendations, and

statistical reviews.

Recent publications are available in their entirety on the Web at <http://www.ntsb.gov>. Other information about available publications also

may be obtained from the Web site or by contacting:

National Transportation Safety Board

Public Inquiries Section, RE-51

490 LíEnfant Plaza, S.W.

Washington, D.C. 20594

(800) 877-6799 or (202) 314-6551

Safety Board publications may be purchased, by individual copy or by subscription, from the National Technical Information Service. To

purchase this publication, order report number PB2001-917004 from:

National Technical Information Service

5285 Port Royal Road

Springfield, Virginia 22161

(800) 553-6847 or (703) 605-6000

The Independent Safety Board Act, as codified at 49 U.S.C. Section 1154(b), precludes the admission into evidence or use of Board reports

related to an incident or accident in a civil action for damages resulting from a matter mentioned in the report. 
iii Safety Study

Contents

Acronyms and Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv

Executive Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v

Chapter 1: Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Oversight of Public Aircraft Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

FAA Analysis of Public Aircraft Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Chapter 2: Accident and Exposure Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Accident Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Exposure Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

All Public Aircraft Operations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Federal Public Use Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Chapter 3: Accident Rates. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Chapter 4: Accident Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Accident Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Trends and Seasonal Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Aircraft Category . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Local Versus Point-to-Point. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

First Occurrence. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Phase of Flight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Causes or Contributing Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Pilot Certification. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Chapter 5: Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Recommendations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Appendixes

A: Partial List of Federal Aviation Safety Regulations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

B: Statutory Definition of “Public Aircraft” . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

C: Effect On the Public Aircraft Accident Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

D: Selected Portions of 14 CFR Part 47 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
iv Safety Study

Acronyms and Abbreviations

Abbreviated Terms

Air-21 Wendell H. Ford Aviation Investment and Reform Act 

for the 21st Century

CAP Civil Air Patrol

CFR Code of Federal Regulations

FAA Federal Aviation Administration

FAIRS Federal Aviation Interactive Reporting System

FAMIS Federal Aviation Management Information System

GA general aviation

GADIT General Aviation Data Improvement Team

GA survey General Aviation and Air Taxi Activity Survey

GSA General Services Administration

ICAP Interagency Committee for Aviation Policy

OMB Office of Management and Budget

PCIE Presidentís Council on Integrity and Efficiency

USPS United States Postal Service

VIS Vital Information Statistics
v Safety Study

Executive Summary

Section 702 of Public Law 106ñ181, the Wendell H. Ford Aviation Investment and

Reform Act for the 21st Century, directed the National Transportation Safety Board to

ìconduct a study to compare the safety of public aircraft and civil aircraft,î and to review

safety statistics on aircraft operations since 1993. ìPublic aircraftî 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 ìcivilî (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 1993ñ2000. Using activity data from the Federal Aviation

Administration (FAA) (for the period 1996ñ1999), 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 1996ñ

1999), 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 FAAís 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 FAAís 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.

1 Safety Study

Chapter 1

Background

Section 702 of Public Law 106ñ181, the Wendell H. Ford Aviation Investment and

Reform Act for the 21st Century (Air-21), directed the National Transportation Safety

Board to ìconduct a study to compare the safety of public aircraft and civil aircraft,î and

to review safety statistics on aircraft operations since 1993. ìPublic aircraftî 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

ìcivilî (or civilian) aircraft. (Appendix A provides a partial listing.)1 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.2

The Independent Safety Board Act Amendments of 1994 narrowed the definition

of public aircraft, expanding the number of nonpublic government aircraft operations

(considered ìcivilî by the Federal Aviation Administration (FAA)). The act specified that,

among other things, public aircraft status did not attach to government-owned aircraft

transporting passengers (other than those persons required to be on board the aircraft to

accomplish the government function for which the aircraft is operated, such as search and

rescue or in-flight research), unless the aircraft was operated by the Armed Forces or a

United States intelligence agency.3

 Air-21 further redrafted the definition of public

aircraft, modifying the statutory language to more clearly specify requirements for public

aircraft status.

1 Although all aircraft must follow certain sections of 14 CFR Part 91, public aircraft operators do not

have to comply with safety regulations, including maintenance rules under 14 CFR Part 43 or pilot

certification standards under 14 CFR Part 61.

2 Aircraft used by the Department of Defense are also public aircraft, but this study considered only

nonmilitary, nonintelligence aircraft.

3 P.L. 103ñ411. The 1994 amendments also bestowed upon NTSB, for the first time, specific

jurisdiction to investigate all accidents involving public aircraft, except those public aircraft operated by the

Armed Forces or by a United States intelligence agency. Prior to the 1994 amendments, however, the NTSB

had in place memoranda of understanding with many government operators that enabled NTSB

investigation of a number of public aircraft accidents.
2 Safety Study

The term ìpublic aircraftî is actually somewhat misleading because the phrase

refers not to a specific population of aircraft, but to government-sponsored flights meeting

specific criteria laid out in the Code of Federal Regulations (CFR). Essentially, public

aircraft operations are a subset of government-sponsored aircraft operations (figure 1).

The regulations determining whether a particular flight qualifies for public aircraft

status are complicated. Appendix B presents the current statutory definition of ìpublic

aircraft.î In this report, the term ìpublic aircraft operationsî will be used to describe flight

operations meeting the statutory definition of public aircraft detailed in appendix B.

ìPublic aircraftî will describe aircraft performing these operations. ìGovernment aircraft

operationsî will describe the larger set of flight operations conducted to perform a

government function (of which public aircraft operations are a part).

Oversight of Public Aircraft Operations

Because public aircraft operators are exempted from certain aviation safety

regulations, government organizations conducting public aircraft operations supervise

their own flight operations without oversight from the FAA. Oversight policies are most

clearly specified at the Federal level. A circular issued by the U.S. Office of Management

and Budget (OMB) has guided aircraft management at executive agencies of the Federal

government since 1983.4 A 1989 revision of the circular directed the U.S. General

Figure 1. Government aircraft operations 

versus ìpublic aircraftî operations.

4 OMB Circular A-126 ìImproving the Management and Use of Government Aircraft.î

Government Aircraft

Operations

"Public Aircraft"

Operations

Background
3 Safety Study

Services Administration (GSA) to create and maintain a single office responsible for

oversight of Federal aircraft management and to establish a single interagency committee

for assisting the GSA in this role. This led to the creation of the Interagency Committee

for Aviation Policy (ICAP).5 A 1992 revision of the circular specified, among other

things, requirements for aviation safety programs within Federal agencies, adding the

responsibility for collecting accident and incident data. In addition, the revision

recommended that Federal agencies adhere voluntarily to portions of the Federal Aviation

Regulations from which they were exempted.

The United States Senate Committee on Governmental Affairs, Subcommittee on

General Services, Federalism, and the District of Columbia, chaired by Senator Jim Sasser

(DñTN), began a study of the Federal governmentís management of its civilian aircraft

fleet in August 1991. In its report, Management of Federal Civilian Aircraft: Findings and

Recommendations, presented to President William J. Clinton in April 1993, the

subcommittee reported that information concerning inventory and usage of aircraft was

inaccurate or incomplete, that many aircraft were underutilized, and that there were no

binding safety standards in effect. In addition, the subcommittee concluded that the GSA

had been hampered in dealing with other executive agencies by a perception that the GSA

lacked adequate authority and aviation-related expertise. In response to these findings, the

subcommittee proposed a blueprint for reforming the management of government aircraft.

Executive agencies responsible for government aircraft operations were directed to

cooperate with an audit conducted by the GSA inspector general. In addition, the

subcommittee recommended that Congress consider eliminating ìthe exemption of

Federal civilian aircraft from commercial aviation safety requirements, providing for

specific exemptions only after the demonstration of unusual or extraordinary government

needs.î6

Three well-publicized public aircraft accidents in a 14-month period in 1992 and

1993 also brought scrutiny on government aircraft operations, and public aircraft

operations in particular. On August 7, 1992, a State-owned Sikorski S-76A helicopter

crash-landed near Graefenburg, Kentucky, seriously injuring five of the six persons

aboard, including the Governor of Kentucky.7

 The Safety Board reported that the probable

cause of this accident was an inadequate preflight inspection by the flight crew who failed

to ensure that all four of the engine cowling latches were properly secured, which resulted

in subsequent failure of section II of the tail rotor drive shaft after the cowling contacted

the main rotor blades and tail rotor drive shaft.

On April 19, 1993, a State-owned Mitsubishi MU-2B-60 crashed near Zwingle,

Iowa, following the in-flight loss of a propeller blade at 24,000 feet, killing South Dakota

5 The GSA established the ICAP in 1989 at the direction of the OMB. The GSA chairs the committee.

About 17 Federal agencies are members, although this number varies from year to year. With advice from

ICAP, GSA makes policy for Federal aviation management.

6 United States Senate Committee on Governmental Affairs, Subcommittee on General Services,

Federalism, and the District of Columbia [Jim Sasser, Chairman], Management of Federal Civilian Aircraft:

Findings and Recommendations (Washington, DC: U.S. Senate, April 2, 1993).

7 NTSB Accident No. NYC92GA147.

Background
4 Safety Study

Governor George Mickelson and eight others.8 The Safety Board reported that the

probable cause of this accident was fatigue cracking and fracture of the propeller hub arm.

The resulting separation of the hub arm and the propeller blade damaged the engine,

nacelle, wing, and fuselage, thereby causing significant degradation of aircraft

performance and control that made a successful landing problematic. The cause of the

propeller hub arm fracture was a reduction in the fatigue strength of the material because

of manufacturing and time-related factors, that reduced the fatigue resistance of the

material, probably combined with exposure to higher-than-normal cyclic loads during

operation of the propeller at a critical vibration frequency which was not appropriately

considered during the airplane/propeller certification process.

On October 26, 1993, a Beechcraft 300-F owned and operated by the FAA crashed

into a mountain near Front Royal, Virginia, while on an airport inspection trip, killing

three persons.9 In its accident report, the Safety Board faulted the FAA flying program for

inadequate management oversight, stating that the probable cause of this accident

encompassed not only the failure of the pilot-in-command to ensure that the airplane

remained in visual meteorological conditions over mountainous terrain, but also the

failure of the FAA executives and managers responsible for the FAA flying program to:

(1) establish effective and accountable leadership and oversight of flying operations; (2)

establish minimum mission and operational performance standards; (3) recognize and

address performance-related problems among the organizationís pilots; and (4) remove

from flight operations duty pilots who were not performing to standards.

In December 1996, the Presidentís Council on Integrity and Efficiency (PCIE)

issued a report on the Federal civilian agenciesí aircraft management programs.10 A series

of audit reports (20 reports covering 11 different agencies) prepared by the GSA inspector

general were included in the PCIE report. These audits confirmed the safety-related,

operational, and administrative shortcomings described in the Sasser report. The GSA

found frequent and significant instances where agency safety standards (generally less

stringent than FAA safety regulations) were not being met. The authors of the PCIE report

lauded the provision of the Independent Safety Board Act Amendments of 1994 requiring

government aircraft operations involving carriage of passengers or cargo to comply with

FAA standards. The report also acknowledged the provision giving the Safety Board the

responsibility and authority to investigate all nonmilitary, nonintelligence public aircraft

accidents, commenting, ìthese actions go a long way towards addressing the concerns

relating to aircraft safety.î

In 1997, the Associate Administrator, Office of Governmentwide Policy, GSA,

established an independent Aircraft Management Policy Advisory Board to examine all

aspects of the management of federally sponsored aviation programs, including safety

aspects. In June 1998, the advisory board reported that, although progress had been made

8 NTSB Accident No. DCA93GA042.

9 NTSB Accident No. DCA94GA010.

10 Presidentís Council on Integrity and Efficiency, Combined Report on the Federal Civilian Agenciesí

Aircraft Management Programs, Report No. A43006/O/W/F97011 (Washington, DC: PCIE, December 16,

1996).

Background
5 Safety Study

on the issues raised in the Sasser and PCIE reports, fundamental problems remained, and

these problems stemmed from a lack of independent safety oversight of Federal aircraft

operations. In addition, the advisory board referred to ìa continuing questioning of GSAís

role in Federal public aircraft management,î stating, ìthere is widespread uncertainty

about who is in charge, and there is no clear enforcement authority.î As a result of these

findings, the advisory board recommended: (a) the revision of OMB Circular A-126 to

better define GSAís authority to set aircraft management policy and safety guidelines, (b)

the proposal of statutory language to Congress that would place the responsibility for

regulation, oversight, and enforcement of all Federal government aircraft operations on

the FAA, and (c) the allocation of resources to the FAA commensurate with this increase

in responsibilities.11 The advisory board also recommended that the GSA associate

administrator be designated chair of the ICAP, and that ICAP member agencies appoint

representatives of equivalent stature to ease GSAís dealings with the member agencies on

matters involving aircraft management.

Since the release of the advisory boardís recommendations, GSA has assisted the

OMB in drafting a revision of Circular A-126. GSA also drafted a revision of its own

regulations, to be contained in 41 CFR 102-33, to better define its authority for aircraft

management. Both revisions are being reviewed by OMB and have yet to be formally

approved. The GSA deputy associate administrator met with representatives of the FAA

and congressional staff members in mid-1998 to discuss the advisory boardís

recommendation that GSA propose statutory language to Congress placing the

responsibility for regulation, oversight, and enforcement of all Federal government

aircraft operations on the FAA. According to a representative of the GSAís Aircraft

Management Policy Division, neither the FAA nor congressional staff members present at

that meeting were receptive to the recommendation. No further action has been taken. In

other developments, the GSA has designated its associate administrator as the chair of

ICAP, and some of ICAPís member agencies have appointed representatives of equivalent

stature to ease GSAís dealings with those agencies.

FAA Analysis of Public Aircraft Safety

The FAA performed an analysis of public aircraft safety in 1997.12 This study,

which explored the legislative history and the characteristics of government-owned or

government-operated aircraft and examined available safety data, was never published. It

was, however, used as the basis for a briefing of the U.S. General Accounting Office,

which was examining the issue of public aircraft safety in response to the conclusions and

recommendations published in the report of the GSAís Aircraft Management Policy

Advisory Board. The number of aircraft engaged in government aircraft operations was

estimated in the FAA study using preliminary data from the ICAP, which had begun to

11 U.S. General Services Administration, Report of the Aircraft Management Policy Advisory Board

(Washington, DC: GSA, 1998).

12 Federal Aviation Administration Office of Accident Investigation, Safety Analysis Branch, ìAn

Analysis of Public Aircraft Safetyî (Washington, DC: FAA, 1997, unpublished document).

Background
6 Safety Study

build a list of aircraft owned or operated at all levels of government,13 and data from the

FAAís National Vital Information Statistics (VIS) database.14 The FAA compared

accident characteristics for government versus general aviation (GA) operations, and

across levels of government. The resulting FAA analyses were of limited value because

the FAA lacked activity statistics for government aircraft operations.

Since that time, the FAA has begun publishing public aircraft flight hour

estimates. The FAA first released estimates in 1997 for the 1996 calendar year. In its

study, the Safety Board used these data to compare the safety of public and civil aircraft

operations.15 The Board calculated accident rates for the period 1996ñ1999 rather than

1993ñpresent because FAA estimates of public aircraft activity were available only for

these years. Furthermore, the Board was not responsible for investigating most public

aircraft accidents prior to mid-1995. Before 1996, the Boardís public aircraft accident

record is less complete. In short, the period 1996ñ1999 was the time frame for which

complete data were available. The remainder of the report discusses the calculation of

these rates, comparison of accident characteristics, and data limitations encountered by

Safety Board staff during the course of this effort to compare the safety of public and civil

aircraft.

13 This data collection effort, performed primarily by the Department of Energy, an ICAP member, has

since been discontinued because of difficulties in maintaining the currency of the data set.

14 The FAA uses the VIS database to track commercial and government certificates.

15 Accident rates are calculated by dividing accidents by some measure of transportation activity, such

as trips taken, miles traveled, or hours spent in transit. This adjustment is sometimes called ìnormalization.î

The rationale for normalization is as follows: travelers and system operators run the risk of experiencing a

transportation accident primarily when they travel. The more people travel, the more they are exposed to

risk, and the more likely they are to be involved in a transportation accident.

Background
7 Safety Study

Chapter 2

Accident and Exposure Data

Accident Data

The Safety Board maintains the official government census of civil aviation

accidents and, as of April 23, 1995, certain public aircraft accidents as well.16 The

Independent Safety Board Act Amendments of 1994 required most public aircraft

operators to report accidents to the Safety Board. The Board relies on its investigators to

identify incoming reports of public aircraft accidents, and to distinguish these from civil

aircraft accidents. Investigators code accident-involved public aircraft ìpublic useî or

ìinvestigation of a government agencyî as they enter accident data in the Boardís

Aviation Accident/Incident Database. Based on these codings, Safety Board staff

identified over 300 accidents that occurred between January 1993 and December 2000.

Staff reviewed a brief report of each accident in the sample. The case-by-case

review of the public aircraft accident sample could not ensure that every accident flight

was operated in a manner consistent with the statutory definition of public aircraft in

effect at the time the accident occurred. The statutory definition of public aircraft status

takes many factors into account that are not documented in a typical aircraft accident

record (for example, length of the lease agreement for State governments, presence of

nonessential crewmembers, and so on). The purpose of the review was merely to look for

cases where the information in the accident record was clearly inconsistent with

classification of an aircraft operation as public.

Staff inspected each case to determine whether the owner or the operator of the

accident aircraft was a nonmilitary, nondefense government organization. If so, the case

was retained. If not, the long narrative and the accident docket for that accident were

examined for other information suggesting that the aircraft was on a governmentsponsored mission. If such evidence was found, the case was retained. If no such

information was found, the case was discarded. Eleven accidents (3 percent of the

accident set) were eliminated from the sample based on these criteria. Three additional

accidents were discarded during the review process because they involved aircraft

operated by non-U.S. governments that crashed outside U.S. territory.17 Although they

were on a mission sponsored by a military organization, two privately owned aircraft

operating under contract to the U.S. Coast Guard and seven privately owned aircraft

operating under contract to the Department of Defense were included in the accident

sample because the operators were civilian. These aircraft are excluded from the accident

sample used for calculating the Federal aircraft accident rate later in this report.

16 The Safety Board does not maintain official records of military or intelligence aircraft accidents.

17 NTSB Accident Nos. FTW97RA314, IAD00RA033, and SEA00WA163.
8 Safety Study

During the review, staff noticed one systematic error made by the Safety Boardís

investigators: Civil Air Patrol (CAP) accidents were coded public use, despite the fact that

CAP flights are not technically considered public aircraft. CAP aircraft were left in the

accident sample because the FAA includes CAP flight hours in its estimate of public use

flight activity. (Appendix C gives a more detailed explanation.)

The final sample consisted of 343 public aircraft involved in 341 accident events

(table 1). These accidents resulted in 167 deaths and 220 injuries. Each record contained

information on a variety of event-, aircraft-, and occupant-related variables. Staff

classified the accidents in terms of severity using a four-category classification system

developed by the Board for classifying air carrier accidents (table 2).18 Staff also classified

accident-involved public aircraft according to the level of government served (table 3).

The majority of the missions (51 percent) were Federal. The rest were divided evenly

between State and local governments. Five pre-1996 accident aircraft could not be

categorized by level of government because their accident records lacked sufficient

detail.19

18 This classification system was developed by the Safety Board in response to congressional direction

under the Federal Aviation Reauthorization Act of 1996 to develop a system that was more informative than

the traditional fatal/nonfatal dichotomy.

19 NTSB Accident Nos. ATL93T#A01, MIA93T#A02, FTW94T#A03, SEA94T#A05, and

ANC95T#A01.

Accident and Exposure Data
9 Safety Study

Table 1. Accident-involved public aircraft and associated injuries, 1993ñ2000.a

Accident severity Injuries

Type of operation Year

Accident

aircraft Fatal Nonfatal

Persons 

killed

Persons 

injured

Persons 

uninjured

Public Aircraft 1993 36 8 28 23 25 50

1994 46 10 36 24 48 42

1995 45 9 36 19 18 49

1996 42 6 36 12 20 42

1997 41 9 32 15 34 43

1998 46 15 31 25 23 46

1999 41 6 35 22 31 54

2000 46 15 31 27 21 36

Total 343 78 265 167 220 362

General Aviation b 1993 2,059 405 1,654 740 1,020 2,227

1994 2,014 410 1,604 730 1,052 2,188

1995 2,077 420 1,657 734 964 2,242

1996 1,939 368 1,571 634 898 1,944

1997 1,873 362 1,511 641 914 1,928

1998 1,930 377 1,553 628 892 1,937

1999 1,938 349 1,589 630 925 2,032

2000 1,870 356 1,514 630 844 1,990

Total 15,700 3,047 12,653 5,367 7,509 16,488

Air Taxi 1993 87 23 64 42 24 41

1994 96 29 67 63 32 36

1995 88 26 62 52 14 23

1996 102 30 72 63 22 23

1997 100 20 80 39 23 31

1998 86 17 69 45 10 40

1999 87 17 70 38 14 31

2000 92 23 69 71 10 43

Total 738 185 553 413 417 1,296

a Statistics for general aviation and air taxi operations are provided as context for the public aircraft accident statistics. 

Accident-involved public, general aviation, and air taxi aircraft were identified by Safety Board staff using the Boardís 

Aviation Accident/Incident Database.

b The Boardís policy has been to include public aircraft accidents that are investigated by the Board in the category 

ìgeneral aviationî for press releases containing aviation safety statistics and for the Annual Review of Aircraft Accident 

Data. This practice was continued here to maintain consistency with aviation safety statistics previously published by 

the Board. As a result, 285 public accident aircraft and related injuries were included in the general aviation statistics 

presented in this table. Most of these accidents occurred during 1995 and later years.

Accident and Exposure Data
10 Safety Study

Exposure Data

The Safety Board gathered government aircraft flight hour data from two sources:

the FAA Office of Aviation Policy and Plans, and the GSA Aircraft Management Policy

Division. The FAA publishes activity estimates for ìpublic useî aircraft operations, a

category that is similar to but less restrictive than the statutory definition for public

aircraft.20 The GSA collects flight hour data from executive agencies of the Federal

government that operate aircraft. The two sets of exposure data cover overlapping sets of

operations, but they are collected independently. The FAA estimates activity for all levels

Table 2. Classification of public, general aviation, and air taxi accidents by severity.a

Public General aviation Air taxi

Severity Accidents Percent Accidents Percent Accidents Percent

Major 109 32 4,247 27 205 33

Serious 29 9 1,148 7 39 6

Injury 1 0 126 1 6 1

Damage 202 59 9,957 64 379 60

Unknown 31 0 1 0

Total 341 100 15,509 100 630 100

a Statistics for general aviation and air taxi operations are provided as context for the public aircraft accident statistics. 

Accident-involved public, general aviation, and air taxi aircraft were identified by Safety Board staff using the Boardís 

Aviation Accident/Incident Database. Multiple-aircraft accidents were counted as a single event for this table. Accident 

severity was defined as follows: major accidentóan aircraft was destroyed, more than one person was killed, or an 

aircraft was substantially damaged and one person was killed; serious accidentóno airplanes were substantially 

damaged but one person was killed, or an aircraft was substantially damaged and at least one person was seriously 

injured; injury accidentóno airplane was substantially damaged but at least one person was seriously injured; damage 

accidentóan aircraft was substantially damaged and no one was killed or seriously injured.

Table 3. Level of government served by accident-involved public aircraft, 1993ñ2000.a

Year of accident Federal State Local Unknown Total

1993 18 7 9 2 36

1994 22 10 12 2 46

1995 22 11 11 1 45

1996 27 9 6 42

1997 19 12 10 41

1998 27 9 10 46

1999 14 13 14 41

2000 25 10 11 46

Total 174 81 83 5 343

a Accident-involved public, general aviation, and air taxi aircraft were identified by Safety Board staff using the Safety 

Boardís Aviation Accident/Incident Database. Level of government mission was determined by examining the aircraft 

operator and the narrative information contained in Board accident records. Five accident aircraft (cases ATL93T#A01, 

MIA93T#A02, FTW94T#A03, SEA94T#A05, and ANC95T#A01) could not be categorized. All five of these aircraft 

crashed prior to 1996, and these accidents were not investigated by Safety Board personnel.

20 The FAA defines ìpublic useî aircraft operations on its flight hour survey questionnaire as ìFederal,

state, or local government owner or leased aircraft used for the purpose of fulfilling a governmental

function.î

Accident and Exposure Data
11 Safety Study

of government; the GSA reports activity only for the Federal government.21 Both sets of

activity statistics describe populations of government aircraft operations that are broader

than the population of operations qualifying for public aircraft status. However, they are

the best data currently available.

The Safety Board could not find independent estimates of State or local public

aircraft activity. The PCIE report in 1996 acknowledged the difficulty in finding such

information, as did the FAAís unpublished analysis of public aircraft safety in 1997.

During the search for data on State and local public aircraft operators, the Safety Board

could not locate even a comprehensive list of State or local government aircraft operators.

The National Association of State Aviation Officials provided a list of 165 aircraft

involved in State executive transportation. Since the statutory change in 1994, however,

executive travel has not been categorized as a public aircraft operation. The U.S.

Department of Agriculture provided a list of State forestry contacts. However, this list of

contacts included county agencies, local agencies, Federal employees, and private

citizens, with no clear means to distinguish among the operators in terms of level of

government. The Airborne Law Enforcement Association indicated that the organization

did not maintain a comprehensive list of operators or operational data. After repeated

efforts yielded no useful information, the Safety Board proceeded with the study using the

best approximations of public aircraft activity available: flight hour estimates from the

FAA and the GSA.

All Public Aircraft Operations

The FAA Office of Aviation Policy and Plans obtains its public use aircraft

activity estimates from the FAA-sponsored General Aviation and Air Taxi Activity

Survey (GA survey). The first GA survey took place in 1978,22 collecting data on flight

activity during the 1977 calendar year. Since 1978, the name of the survey has changed,

but the FAAís overall approach to estimating nonairline flight activity has remained the

same, with some minor changes in the design of the sampling process. Questionnaires for

the 1999 survey were mailed to the registered owners of over 30,000 nonairline aircraft

(about 12 percent of the fleet).23 The FAA selected these aircraft from all aircraft records

in the FAAís Civil Aviation Registry, using a stratification procedure based on 19 aircraft

categories and 9 geographic regions. Combining these two dimensions yielded 172

different aircraft groups from which samples were drawn at random. In statistical terms,

these groups are referred to as cells of the sample frame matrix. Within each cell, a

predetermined number of aircraft were selected for inclusion in the survey. The number of

21 These activities do not include military or intelligence aircraft operations.

22 Prior to 1978, the FAA used the Aircraft Registration Eligibility, Identification, and Activity Report,

AC Form 8050, to collect data on GA activity and avionics. The form was sent to all owners of civil aircraft

in the United States and served two purposes: Part 1 was a mandatory aircraft registration revalidation form,

and Part 2 was voluntary and applied to GA aircraft only, asking questions on the owner-discretionary

characteristics of the aircraft such as flight hours, avionics equipment, base location, and use. This

information was used by the FAA to estimate aircraft activity.

23 The FAA surveys aircraft owners, not pilots, because the GA survey is also used to acquire

information on aftermarket avionics equipage and because pilots commonly fly multiple aircraft. 

Accident and Exposure Data
12 Safety Study

aircraft selected were chosen to minimize sampling error and to ensure that individual

aircraft owners were surveyed as infrequently as possible.

Each aircraft owner selected for inclusion in the 1999 survey received a

standardized 19-question GA survey form. This form requested the following information:

hours flown by the aircraft during the calendar year, lifetime airframe hours, percentage of

flight hours that the aircraft operated while rented or leased, and proportion of flight hours

under different flight plans and weather conditions. In addition, owners were asked to

estimate the percentage of hours flown for each of 15 different purposes (table 4). ìPublic

useî was included as a response category for 1996 and subsequent years. Beginning with

the 1996 survey data, the FAA estimated public aircraft flight hours by multiplying an

aircraftís total flight hours by the percentage of hours flown for ìpublic use,î weighting

each product by an appropriate constant related to the sample design, and summing the

results across aircraft.

While studying the FAAís public aircraft flight hour estimation process, the Safety

Board identified important weaknesses that should be discussed in this report, because the

comparison of public and civil aircraft safety contained in this report depended on the

reliability and validity of flight hour estimates.

First, as mentioned earlier, the definition of ìpublic useî provided on the GA

survey form is broader than the statutory definition for public aircraft. The definition on

Table 4. Purpose-of-flight categories for the 1999 GA survey.a

1. Personal/Recreational: Flying for personal reasons (excludes business transportation)

2. Instructional: Flying under the supervision of a flight instructor (includes student pilot solo; excludes proficiency 

flight)

3. Business Transportation: Individual use for business transportation without a paid, professional crew

4. Corporate/Executive Transportation: Business transportation with a paid, professional crew

5. Regional/Commuter: 14 CFR Part 135 scheduled passenger service only

6. Air Taxi: 14 CFR Part 135 on-demand passenger and all cargo operations (not scheduled passenger service 

or air tours)

7. Air Tours: Commercial sight-seeing conducted under 14 CFR Part 135

8. Sightseeing: Commercial sight-seeing conducted under 14 CFR Part 91

9. Public Use: Federal, state, or local government owner or leased aircraft used for the purpose of fulfilling a 

governmental function

10. Aerial Observation: Aerial mapping/photography, patrol, search and rescue, hunting, traffic advisory, 

ranching, surveillance, oil and mineral exploration, etc.

11. Aerial Application in Agriculture and Forestry: Crop and timber production and protection

12. Other Aerial Application: Public health sprayings, cloud seeding, firefighting, including forest fires, etc.

13. External Load: Operation under 14 CFR Part 133, rotorcraft external load operations, examples include; 

helicopter hoist, hauling logs, etc.

14. Air Medical Services: Air ambulance services, rescue, human organ transportation

15. Other Work Use: Construction work (not 14 CFR Part 135 operation), parachuting, aerial advertising, towing 

gliders, etc.

a These categories and associated definitions were provided on the 1999 General Aviation and Air Taxi Activity survey 

form.

Accident and Exposure Data
13 Safety Study

the survey form actually refers to all government aircraft operations. Therefore, the flight

hour estimate is an inflated substitute for actual public aircraft flying activity.

Second, the estimation of aircraft flight hours by purpose of flight depends, to a

great extent, on the record-keeping policies and memories of aircraft owners, and, in some

cases, the willingness and ability of aircraft owners to obtain needed information from the

pilots who fly their aircraft. When the owner is not the sole operator of an aircraft, the

owner may have difficulty estimating flight hours by purpose of flight. It is difficult to

know the extent to which these difficulties might distort flight hour estimates, but the

potential for error clearly exists.

Third, the FAAís Civil Aviation Registry records are used to estimate the size and

characteristics of the GA fleet and as a source of contact information for mailing surveys

to aircraft owners. After surveys are returned, registry data are used to extrapolate

reported activity to the entire GA fleet. The quality of the activity estimates derived from

the GA survey depends greatly on the accuracy and completeness of records in the

registry. However, the FAA contractor responsible for conducting the GA survey recently

estimated that the proportion of incorrect GA aircraft records in the registry lies between

19 and 40 percent.24

In order to explain how this could be possible, it is important to understand the

FAAís aircraft registration policies (as specified in 14 CFR Part 47). When someone

purchases an aircraft they intend to operate, they must submit an application for

registration to the Civil Aviation Registry. This application contains certain information

about the aircraft as well as contact information for the aircraft owner. After initial

registration, 14 CFR 47.45 requires the aircraft owner to notify the FAA aircraft registry

within 30 days of any permanent change of address. After 3 years has elapsed since receipt

of registration information from an aircraft owner, the FAA sends a Triennial Aircraft

Registration Report form. The aircraft owner is required to return this form within 60

days, verifying basic aircraft information as well as contact information for the owner.

Although 14 CFR 47.51 specifies that ìRefusal or failure to submit the Triennial Aircraft

Registration Report with the information required by this section may be cause for

suspension or revocation of the Certificate of Aircraft Registration,î the FAA has not

enforced this requirement for at least 20 years. Neither has the FAA enforced the

requirement to submit notification to the FAA within 30 days of a permanent change of

address. (Appendix D provides selected portions of 14 CFR Part 47 describing aircraft

registration requirements.)

Owner contact information and other parts of an aircraft record are outdated for

many aircraft. Evidence also suggests that the currency of the registry continues to

deteriorate. Each year, the contractor conducting the GA survey excludes aircraft owners

24 Based on analyses by the FAAís principal contractor for the GA survey, PA Consulting, as described

in a memo from Nicholas Nitka and Lark Lee to the FAA on April 6, 2001. Incorrect records were described

as GA aircraft records that did not have correct address information and GA aircraft records in the registry

that were not actually part of the active GA fleet, that is, air carriers, destroyed aircraft, museum aircraft,

military-owned aircraft, and so on.

Accident and Exposure Data
14 Safety Study

from consideration in the survey because the registry database indicates that their contact

information is outdated. The contractor also excludes aircraft owners with postmaster

returns on record from prior GA surveys they have conducted. After these known outdated

records are excluded, a sizable percentage of GA surveys (10 percent in 1999) are returned

by the U.S. Postal Service (USPS) with information indicating that the address is no

longer valid and that the USPS has no forwarding address on file. The FAA contractor

responsible for analyzing GA survey returns has estimated that the number of records in

the Civil Aviation Registry that were valid for inclusion in future GA surveys (after

known outdated records were excluded) decreased from 79 percent in 1999 to 74.8 percent

in 2000.25

In a meeting with Safety Board staff, managers at the Civil Aviation Registry

stated that a fairly constant proportion of owner addresses (currently about 10 percent)

have at least two USPS returns on record in response to triennial registration form

mailings.26 Registry staff reported that they have taken steps to prevent further

deterioration in the accuracy of aircraft records in recent years. On May 4, 1999, the

registry began biannual comparisons between the FAAís database of registered aircraft

owners and the USPSís database of change-of-address forms submitted by U.S. residents.

In cases where a match has been made, the registered aircraft owner was sent a letter

asking whether they wanted their contact information updated to reflect the new address.

About 2,000 of the 20,000 letters sent to aircraft owners under this new program were

mailed back. Some owners requested that the registry change their principal contact

information, and some requested that their principal contact information remain the same.

The reasons why the remaining 18,000 aircraft owners contacted in these mailings did not

respond to the FAA are not documented.

Another way the FAA hopes to improve the currency of its Civil Aviation Registry

is through online verification of aircraft registration information by aircraft owners. The

FAA began offering aircraft owners the capability to query and inspect aircraft

registration information online on April 4, 2001. It is now possible for aircraft owners to

look up their own aircraft on the Internet and examine the accuracy of the aircraft record.

The FAA provides a downloadable form that can be mailed to the registry for correction

of any inaccuracies. Interest in the Web site appears to be high. According to registry

managers, the site had over 300,000 ìhitsî within 2 months of its debut. The managers

hope that this new capability will lead many aircraft owners to submit updated registration

information, thereby improving the currency of the registry. They plan to run ads in

industry magazines encouraging pilots to take advantage of this new method of verifying

the accuracy of their aircraft registration information.

In an interview with Safety Board staff, registry managers stated that they were

opposed to the imposition of civil penalties for violation of aircraft registration

regulations. They felt it would damage the cooperative relationship they have attempted to

25 Memo from Nicholas Nitka and Lark Lee, PA Consulting, to Arthur Salomon, Federal Aviation

Administration, April 6, 2001.

26 Meeting conducted with Mark Lash, Manager, Civil Aviation Registry, and Julie Stanford, Manager,

Aircraft Registration Branch, Civil Aviation Registry, on May 30, 2001.

Accident and Exposure Data
15 Safety Study

cultivate with aircraft owners. They cited an attempt in 1978 to enforce aircraft

registration requirements which resulted in the deletion of 15,323 aircraft records from the

registry before the effort was halted. According to registry personnel, many of these

aircraft were never re-registered. The number of these aircraft that remained active is

unknown. The only real result of this attempt at enforcement, the managers argued, was a

reduction in the number of aircraft records contained in the registry.

Fourth, the GA survey produces imprecise public use flight hour estimates because

of a relatively high level of sampling error. Sampling error estimates provide an indication

of the degree to which random errors associated with the sampling process influence flight

hour estimates. The level of sampling error is partly a function of the number of aircraft

included in the survey sample. As sample size increases, sampling error decreases.

Estimates of sampling error can be used to calculate confidence intervals for flight hour

estimates within a particular category of flight operations. Estimated sampling error for

1999 public use flight activity (expressed in terms of a percent standard error) was 9.7,

compared with much lower standard errors for personal (1.7), business (4.3), instructional

(3.1), or corporate flight hours (5.5).27 As a result, public use activity is being monitored

with less accuracy than other major categories of aviation, reducing the accuracy with

which trends in public aircraft accident rates can be examined.

Fifth, because of the way in which aircraft owners are asked to break down flight

hours according to purpose of flight, the purpose of flight categories provided on the GA

survey form are a mixture of flying tasks and administrative purposes of flight. Therefore,

the categories are not mutually exclusive. For example, a private contractor performing

aerial application work must choose between ìaerial applicationî and ìbusiness

transportation.î Similarly, a government aircraft operator performing public health

sprayings for mosquito control faces a choice between ìother aerial applicationî (which

includes public health spraying) and ìpublic use.î No instructions are provided to help the

respondent choose between categories. It is doubtful that all aircraft owners faced with the

same choice would make the same classification.

The limitations of the GA survey are recognized by those close to the sampling

and activity estimation process but are less apparent to other users of the data, such as

researchers acquiring accident rate statistics through the U.S. Department of

Transportationís Bureau of Transportation Statistics. In an effort to improve the quality of

GA data, a joint government/industry committee, the General Aviation Data Improvement

Team (GADIT) was organized in April 2000. GADIT was organized into several breakout

groups, one of which (the Activity Data Task Group) was directed to examine current

FAA procedures for estimating GA activity data and to look for ways to improve the

quality and timeliness of these estimates.28 The Activity Data Task Group presented

recommendations to the FAA Safer Skies Joint Steering Committee (a

government/industry working group) in May 2001. However, due to differences in

opinion among members of the committee, consideration of these recommendations was

27 Federal Aviation Administration Office of Aviation Policy and Plans, General Aviation and Air Taxi

Activity Survey (Washington, DC: FAA, 1999).

28 There have been previous efforts by industry to improve the data. The General Aviation Coalition

submitted recommendations to the FAA in 1997.

Accident and Exposure Data
16 Safety Study

deferred. No action was taken and no date was set for further consideration of these

recommendations.

Most of the GADIT Activity Data Task Groupís recommendations focused on the

improvement of existing survey process (clarifying purpose-of-flight definitions, adding

questions, increasing sample size). There were, however, three recommendations to

ìenhanceî the Civil Aviation Registry. These included asking each owner to periodically

respond to address verification requests, even if the address had not changed; making

registration mandatory every 3 years (one-third of the owners each year) and requiring

completion of the GA survey when registration is filed; or having the registry provide

voluntary revalidation of aircraft registration. The task group did not favorably assess

alternate data collection methods. These included a suggestion supported by a minority

opinion filed with the groupís report that would require FAA airworthiness inspectors to

submit a record of flight hours on an aircraft when it receives an annual inspection.

Federal Public Use Operations

The Safety Board obtained Federal aircraft activity data from the GSA Aircraft

Management Policy Division. The GSA has been responsible for collecting information

on Federal aircraft ownership, utilization, and cost accounting since 1989, as directed by

OMB Circular A-126. Rather than surveying by mail, the GSA collects complete records

of activity from Federal agencies. Seventeen Federal agencies currently report these data

to the GSA (table 5).29 In recent years, these agencies have submitted total annual flight

hours statistics, broken down according to whether the aircraft used were federally owned,

leased, or chartered. However, the GSA began collecting more detailed Federal aircraft

activity data using a new Internet-based reporting system called the Federal Aviation

Interactive Reporting System (FAIRS) in April 2000. FAIRS will provide easily

accessible quarterly reports of cost and utilization data, as well as flight hours coded

according to aircraft class and mission characteristics. The first complete year of FAIRS

activity data will be available after the end of calendar year 2001. The FAIRS system will

also contain a complete census of Federal aircraft by the end of 2001. Eleven mission

category codes are being used to categorize flight hours in the FAIRS system (table 6),

with more detailed subcategories available within these categories.

29 The number of reporting agencies can change from year to year depending on aircraft utilization.

Accident and Exposure Data
17 Safety Study

Table 5. Federal agencies reporting aircraft activity data to the U.S. General Services 

Administration for the year 1999.a

Agency or Department

Number of 

governmentowned aircraft

Hours flown: 

government 

aircraft

Hours flown: 

contract, 

charter, rental

Hours 

flown: total

1. Department of Agriculture 365 19,920 78,348 98,268

2. Department of Commerce 14 3,708 3,708

3. Department of Energy 29 8,980 1,047 10,027

4. Department of Health and Human 

Services

 1,371 1,371

5. Department of Housing and Urban 

Development

6. Department of Justice 321 102,094 10,449 112,543

7. Department of State 98 19,933 19,933

8. Department of the Interior 107 21,574 52,852 74,426

9. Department of the Treasury 145 36,009 36,009

10. Department of Transportation 46 21,398 22,347 43,745

11. Department of Veterans Affairs 7 7

12. Environmental Protection Agency 678 678

13. Federal Emergency 

Management Agencyb

14. National Aeronautics and Space 

Administration

 104 2,310 2,310

15. National Transportation Safety 

Board

 21 21

16. National Science Foundation 14 4,002 1,858 5,860

17. Tennessee Valley Authority 11 2,486 81 2,567

Total 1,254 242,414 169,059 411,473

a These data are preliminary. They were obtained from the U.S. General Services Administration, Aircraft Management 

Policy Division. These flight hour data were collected prior to the implementation of GSAís Federal Aviation Interactive 

Reporting System (FAIRS) in April 2000, making it impossible to subdivide hours according to the type of aircraft flown 

or purpose of flight.

b Flight hours for the Federal Emergency Management Agency were unavailable for calendar year 1999.

Table 6. Purpose-of-flight codes used to categorize Federal aircraft flight activity in 

U.S. General Services Administrationís Federal Aviation Interactive Reporting System 

(FAIRS).a

Category

1. Fire fighting and disaster response

2. Flight inspection / calibration

3. Law enforcement

4. Mission support

5. Research and development, including scientific experimentation

6. Resource management

7. Search and rescue

8. Surveillance

9. Training

10. Transportation of cargo

11. Transportation of passengers

a This list of mission categories was obtained from the U.S. General Services Administration (GSA), Aircraft 

Management Policy Division. The GSA began using these categories for collection of aircraft activity data during the 

2000 calendar year. The first complete calendar year of FAIRS data will be 2001.

Accident and Exposure Data
18 Safety Study

Prior to the implementation of FAIRS, Federal agencies submitted brief annual

activity reports to the GSA for the years 1998 and 1999. These reports categorized flight

hours according to the type of financial arrangement (government-owned aircraft,

contract, charter, or rental). However, these reports provided no categorization of flying

activity by aircraft class or mission type. Prior to 1998, Federal agencies reported flight

hours to the GSA using the Federal Aviation Management Information System (FAMIS).

FAMIS records provided much of the same information that will now be reported through

FAIRS, but the FAMIS information was stored in a way that made it very difficult to

access and analyze. In addition, FAMIS data were generally inaccurate, incomplete, and

late.30

Federal government aircraft activity figures are shown in table 7. For the purposes

of this study, the Safety Board collected Federal public aircraft activity data for the years

1996ñ1997 from agency FAMIS submissions and for 1998ñ1999 from the annual flight

hour summaries submitted to the GSA by Federal agencies after the FAMIS was shut

down. The GSA collects activity data on all aircraft operations sponsored by Federal

executive agencies without distinguishing which flight hours were accrued as part of

qualifying public aircraft missions. Therefore, flight hours for Federal government

aviation operations are an inflated substitute for the Federal public aircraft flight hours

they include. The GSA flight hour data, however, are currently the closest available

estimate of Federal public aircraft activity.

30 Presidentís Council on Integrity and Efficiency, Combined Report on the Federal Civilian Agenciesí

Aircraft Management Programs, Report Number A43006/O/W/F97011 (Washington, DC: PCIE, December

16, 1996).

Table 7. Public aircraft flight hours, 1996ñ1999.

a

Year

Public use flight hours

(all levels of government)

Federal aircraft flight hours

(Federal aircraft only)

1996 1,047,000 341,000

1997 1,096,000 383,000

1998 1,373,000 417,000

1999 1,107,000 411,000

Total 4,623,000 1,552,000

a

Activity estimates for all levels of government were obtained from the Federal Aviation Administration Office of 

Aviation Policy and Plans. Activity estimates for Federal aircraft were obtained from the General Services 

Administration Office of Aircraft Management Policy. Federal aircraft hours were adjusted for the years 1996ñ1998 by 

subtracting hours flown by the U.S. Coast Guard, which were included in GSA estimates during this period. U.S. Coast 

Guard flight hours were obtained from the U.S. Department of Transportation Office of Surface Transportation.

Accident and Exposure Data
19 Safety Study

Chapter 3

Accident Rates

Safety Board staff calculated an accident rate of 3.66 per 100,000 flight hours for

all public aircraft operations, and 4.58 per 100,000 flight hours for Federal aircraft

operations, for the period 1996ñ1999 (tables 8 and 9). Although the 4-year accident rate is

higher for all public aircraft than for Federal aircraft, it is difficult to draw firm

conclusions about the difference between the rates. The activity estimates used to

calculate each accident rate contain unknown proportions of nonpublic government

aircraft flight hours. In addition, as described in chapter 2, there are several aspects of the

FAAís processes for estimating public use flight hours that are likely to introduce

nonsampling error to the FAAís public use activity estimates. Furthermore, during the

most recent year for which data were available (1999), the Federal public aircraft accident

rate (2.92) was lower than the overall public aircraft accident rate (3.70).

Table 8. Public aircraft accident rates (all levels of government), 1996ñ1999.a

Year

Flight

hours Accidents

Fatal 

accidents

Nonfatal 

accidents

Accidents 

per 100K 

hours

Fatal 

accidents per 

100K hours

Nonfatal 

accidents per 

100K hours

1996 1,047,000 42 6 36 4.01 0.57 3.44

1997 1,096,000 41 9 32 3.74 0.82 2.92

1998 1,373,000 45 14 31 3.28 1.02 2.26

1999 1,107,000 41 6 35 3.70 0.54 3.16

Total 4,623,000 169 35 134 3.66 0.76 2.90

a Public and general aviation aircraft accidents were identified by the Safety Board using the Safety Boardís aviation 

accident/ incident database. Multiple-aircraft accidents were counted as a single event. Public aircraft flight hours were 

obtained from the U.S. Federal Aviation Administration Office of Aviation Policy and Plans.

Table 9. Federal aircraft accident rates, 1996ñ1999.a

Year

Flight 

hours Accidents

Fatal 

accidents

Nonfatal 

accidents

Accidents 

per 100K 

hours

Fatal 

accidents per 

100K hours

Nonfatal 

accidents per 

100K hours

1996 341,000 22 1 21 6.46 0.29 6.16

1997 383,000 14 5 9 3.65 1.31 2.35

1998 417,000 23 8 15 5.52 1.92 3.60

1999 411,000 12 1 11 2.92 0.24 2.68

1996ñ1999 1,550,000 71 15 56 4.58 0.97 3.61

a Federal and aircraft accidents were identified by the Safety Board using the Safety Boardís aviation accident/incident 

database. Multiple-aircraft accidents were counted as a single event. Accidents involving the Civil Air Patrol and 

privately owned aircraft contracted to the Department of Defense were excluded from this table, because the flight 

activity of these operators was not included in Federal flight activity estimates. Federal aircraft flight hours were obtained 

from the U.S. General Services Administration, Office of Governmentwide Policy. Federal aircraft hours were adjusted 

for the years 1996ñ1998 by subtracting hours flown by the U.S. Coast Guard, which were included in GSA estimates 

during this period. U.S. Coast Guard flight hours were obtained from the U.S. Department of Transportation Office of 

Surface Transportation.
20 Safety Study

Safety Board staff calculated 1996ñ1999 accident rates for several categories of

civil aviation (GA, air taxi operations, scheduled 14 CFR Part 135 operations, and

scheduled 14 CFR Part 121 operations) to provide context for interpreting the public

aircraft accident rates. Subrates were also calculated within some of these sectors for four

combinations of aircraft category (rotorcraft versus fixed-wing) and accident severity

(fatal vs. nonfatal) (table 10). Subrates were not calculated by aircraft category for

scheduled Part 135 or scheduled Part 121 operations because activity data were not

available at this level of detail from the FAA.

At the broadest level of analysis, the accident rate for all public aircraft for the

years 1996ñ1999 (3.66 accidents per 100,000 flight hours) lies between the rate for GA

(7.20 accidents per 100,000 flight hours) and the rates for scheduled Part 135 and Part 121

operations (1.06 and 0.27, respectively). The accident rate for public aircraft (3.66) was

almost identical to the rate for air taxis (nonscheduled Part 135 operations, 3.47 accidents

per 100,000 flight hours) (table 10 and figure 2). Again, any conclusions about the

differences between these accident rates must be considered tentative because it is

Table 10. Accident rates by aviation sector, aircraft category, and accident severity, 

1996ñ1999.a

Aviation sector

Aircraft category, accident severity Accidentsb Flight hoursb Accidents per 100,000 flight hours

General aviation: 7,578 105,190,000 7.20

Rotorcraft, fatal accidents 115 4,991,000 2.30

Rotorcraft, nonfatal accidents 561 4,991,000 11.24

Fixed-wing, fatal accidents 1,268 89,442,000 1.42

Fixed-wing, nonfatal accidents 5,376 89,442,000 6.01

Public aircraft: 169 4,623,000 3.66

Rotorcraft, fatal accidents 16 1,929,000 0.83

Rotorcraft, nonfatal accidents 77 1,929,000 3.99

Fixed-wing, fatal accidents 18 2,536,000 0.71

Fixed-wing, nonfatal accidents 54 2,536,000 2.13

Air taxi: 322 9,290,000 3.47

Rotorcraft, fatal accidents 14 2,201,000 0.64

Rotorcraft, nonfatal accidents 33 2,201,000 1.50

Fixed-wing, fatal accidents 59 6,690,000 0.88

Fixed-wing, nonfatal accidents 217 6,690,000 3.24

Scheduled Part 135:c d 48 4,545,000 1.06

Fatal accidents 11 4,545,000 0.24

Nonfatal accidents 37 4,545,000 0.81

Scheduled Part 121:c 166 60,513,000 0.27

Fatal accidents 9 60,513,000 0.01

Nonfatal accidents 157 60,513,000 0.26

a Aircraft accidents were identified by the Safety Board using the Safety Boardís aviation accident/incident database. 

Multiple-aircraft accidents were counted as a single event. Aircraft flight hours were obtained from the U.S. Federal 

Aviation Administration, Office of Aviation Policy and Plans, Planning Analysis Division.

b Gliders, lighter-than-air craft, and ultralights were not included in fixed-wing accident totals. Autogyros were not 

included in rotorcraft accident totals. In addition, multiple aircraft accidents within a sector sometimes involved both a 

rotorcraft and a fixed-wing aircraft. In these cases, the accident was counted once in each aircraft category. For these 

reasons, the sum of fixed-wing and rotorcraft accidents does not add to the total number of accidents within each sector.

c Flight hours were not available by aircraft category for scheduled 14 CFR Part 135 and scheduled 14 CFR Part 121 

operations.

d Many scheduled 14 CFR Part 135 operators transitioned to operation under 14 CFR Part 121 in 1997 because of a 

change in the Federal Aviation Regulations governing passenger service.

Accident Rates
21 Safety Study

difficult to estimate the combined effects of sampling and nonsampling error that affect

FAA flight hour estimates within these categories.

To examine how much the public aircraft flight hours might be affected by

sampling error alone, Safety Board staff calculated a 90-percent confidence interval using

sampling error statistics from the FAAís 1999 flight activity estimates.31 The confidence

interval for public use flight hours ranges ± 16 percent (between 930,000 and 1,284,000).

This means that the confidence interval for the 1999 public aircraft accident rate (3.70)

actually ranges from 3.19 to 4.41. Staff lacked adequate data to calculate confidence

intervals for the GA or air taxi accident rates because sampling error figures published by

the FAA were not available at the desired level of analysis.32 Even if the Board had been

able to calculate confidence intervals for all of these accident rates, it would still be

difficult to draw conclusions about the differences between public and civil aircraft

accident rates because of the numerous sources of nonsampling error the Board believes

may be influencing the FAA hour estimates (as discussed in chapter 2). Nevertheless, the

effects of nonsampling error would have to be quite large to change the ranked order of

the broad accident rates in each sector (as shown in figure 2), with the exception of the

public and air taxi accident rates, which are quite similar.

The more detailed public, GA, and air taxi accident rates shown in table 10

generally show the same ordering as the overall rates, with public aircraft and air taxi rates

both being substantially lower than GA. There is one exception, however. Although the

rates for nonfatal public and GA rotorcraft accidents are both substantially lower than the

rate for nonfatal GA rotorcraft accidents (2.12 for public and 4.93 for air taxi, compared

with 13.55 for GA), the rate for nonfatal public rotorcraft accidents is more than double

the rate for nonfatal air taxi rotorcraft accidents. Again, it is difficult to assess the

significance of this difference due to the lack of data available for the calculation of

confidence intervals for the rates involved.

Figure 2. Accident rates by aviation sector, 1996ñ1999

31 A 90-percent confidence interval represents the range within which one can be 90 percent confident

that a statistic would lie if sampling could be performed without error.

32 For example, three separate activity figures are routinely combined by the FAA and the NTSB to

estimate air taxi flight activity: air taxi, air tours, and sightseeing. The FAA publishes an estimate of

sampling error for each of these categories individually, but not for all three combined. The Board faced a

similar dilemma when seeking to calculate confidence intervals for GA activity.

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

General Aviation Public Aircraft Air Taxi Scheduled Part

135

Scheduled Part

121

Accidents per 100,000 flight hours

Accident Rates

23 Safety Study

Chapter 4

Accident Characteristics

This chapter describes characteristics of public aircraft accidents. The reader is

cautioned that the statistics presented in this chapter are not representative of all public

aircraft flight operations, only accident flights. Accident flight characteristics likely differ

from the nonaccident flight characteristics.

Statistics describing GA accident flights are presented alongside public aircraft

accident statistics in some of the tables that follow. In addition, some tables provide more

detailed breakdowns within each sector for rotorcraft versus fixed-wing aircraft.

The time frame for most of the analyses covers the period 1995ñ1998 rather than

the period 1996ñ1999, because many of the variables analyzed in this chapter are not

entered in the Safety Board database until an accident investigation is completed and

many of the accident investigations begun in 1999 had not yet been completed at the time

this report was prepared.

Accident Location

Safety Board staff ranked States according to the number of public aircraft

accidents reported during the 1993ñ2000 period. This ranking indicated that California,

Alaska, Florida, and Texas were in the top four. These four States accounted for 46

percent of all public aircraft accidents. These were also the top four States for GA

accidents during the 1993ñ2000 period.

The concentration of nearly half of all public aircraft accidents in four States

probably reflects the magnitude of flying activity within those States. Since the FAA does

not estimate aircraft activity by State, it would be very difficult to analyze the extent to

which the concentration of accidents is merely a function of flight activity. The percentage

of public aircraft accidents by State is shown graphically in figure 3.
24 Safety Study

Trends and Seasonal Components

Staff analyzed trends and seasonal patterns affecting public aircraft accidents

during the study period as well. These analyses indicated that the annual number of public

aircraft accidents has remained stable over the last 8 years. No significant upward or

downward trend was evident (figure 4). The analyses revealed substantial seasonal

influences that affected public aircraft accident totals from month to month, with accidents

peaking in June and reaching their seasonal low in December. The seasonal pattern looks

very similar to that of GA (figure 5).

Figure 3. Percent of all U.S. public aircraft accidents occurring within each State.

10% Plus 5-9% 2-4% 1% 0%

Accident Characteristics
25 Safety Study

Figure 4. Public aircraft accident trend, July 1993ñJune 2000. Trend line based on a 

13-month moving average, which removes seasonal effects. The first and last data 

points were not plotted, due to distortion from the averaging process.

Figure 5. Public versus general aviation accidentsñseaonal factors. Data shown are 

the number of accidents occurring within each calendar month from January 1993 

through December 2000. Accidents involving multiple aircraft were counted as a single 

event.

1

1.5

2

2.5

3

3.5

4

4.5

5

5.5

6

Jan-93

Jul-93

Jan-94

Jul-94

Jan-95

Jul-95

Jan-96

Jul-96

Jan-97

Jul-97

Jan-98

Jul-98

Jan-99

Jul-99

Jan-00

Jul-00

Month

13 Month Moving Average

0

5

10

15

20

25

30

35

40

45

50

Jan

FebMar

Apr

May

Jun

Jul

AugSep

Oct

Nov

Dec

Public Use Accidents 

0

500

1000

1500

2000

2500

General Aviation Accidents 

Public Aircraft General Aviation Aircraft

Accident Characteristics
26 Safety Study

Aircraft Category

Accident aircraft are totaled by category (for example, airplane with single

reciprocating engine, airplane with multiple reciprocating engines, etc.) in table 11. A

higher proportion of public accident aircraft were rotorcraft (47 percent for public aircraft

versus 7 percent for GA, respectively). This likely reflects the higher proportion of

helicopters performing public use flights, which, according to the 1999 GA survey,

generated 49 percent of all public use flight hours, but only 1.6 percent of GA flight hours.

Local Versus Point-to-Point

Accident aircraft totals are presented in table 12 according to whether the accident

flight was local versus point-to-point. Approximately 64 percent of public accident

aircraft were engaged in local flying, compared to only 48 percent of GA accident aircraft.

Furthermore, local public aircraft accident flights were more likely than local GA accident

flights to have crashed at an off-airport location. Neither of these findings is particularly

surprising, considering the kinds of missions flown by public aircraft operators.

Table 11. Public versus general aviation accident aircraft by category.a

Public aircraft General aviation aircraft

Aircraft category Aircraft Percent Aircraft Percent

Airplanes:

Single reciprocating 69 40 5,903 77

Multiple reciprocating 10 6 537 7

Turboprop 6 3 209 3

Turbojet 1 1 73 1

Unknown airplane 4 2 84 1

Total 90 52 6,806 89

Rotorcraft:

Reciprocating 21 12 324 4

Turboshaft 58 33 238 3

Unknown rotorcraft 2 1 5 0

Total 81 47 567 7

Other aircraft 3 2 270 4

All Aircraft 174 100 7,643 100

a Accident aircraft were identified using the Safety Boardís aviation accident/incident database. Data for the period 

1995ñ1998 were included in this analysis. Some percent columns may not add to 100 because of rounding.

Accident Characteristics
27 Safety Study

First Occurrence

When accidents investigated by the Safety Board are entered into the database,

ìoccurrencesî (categories of events leading to the damage or injury) are coded. Staff

sorted occurrence codes into broad categories and counted the number of public versus

GA accident aircraft associated with each category. These aircraft were further grouped in

terms of their involvement in fatal versus nonfatal accidents (table 13). The only

noteworthy difference between the two sectors involved in-flight collisions. A higher

proportion of fatal public aircraft accidents began with an in-flight collision (46 percent

for public aircraft versus 29 percent for GA aircraft (table 13). Followup analyses did not

reveal any obvious difference between the two sectors in terms of the type of collision (for

example, collision with terrain, tree, power line, utility pole, and so on). However, when

broken down to this level of detail, the number of accidents in each category was too small

to make valid comparisons.

Table 12. Type of flight.a

Public aircraft General aviation aircraft

Type of flight Aircraft Percent Aircraft Percent

Local

At airport 28 16 1,642 21

Off airport 83 48 2,113 27

Total 111 64 3,755 48

Point-to-point

Destination 39 22 1,930 25

Origin 13 7 870 11

En route 11 6 1,271 16

Total 63 36 4,071 52

Total 174 100 7,826 100

a Accident aircraft were identified using the Safety Boardís aviation accident/incident database. Data for the period 

1995ñ1998 were included in this analysis.

Accident Characteristics
28 Safety Study

Because public use aircraft accidents involve a higher proportion of rotorcraft than

accidents in other sectors of aviation, staff conducted the same analysis using two subsets

of the accident data presented in table 12 (rotorcraft only (table 14) and fixed-wing aircraft

only (table 15).

Table 13. Public versus general aviation accident aircraft by first occurrence, all 

aircraft categories.a

Public aircraft General aviation aircraft

First occurrence Fatal

Percent 

total

NonfatalPercent 

total Fatal

Percent 

total

NonfatalPercent 

total

Collision:

In-flight 18 47 18 14 425 29 801 13

On ground/water 7 5 4 0 431 7

Noncollision:

In-flight 15 39 27 21 711 49 1,140 18

Power-related 5 13 37 29 247 17 1,949 32

On ground/water 34 27 32 2 1,596 26

Miscellaneous 4 3 22 2 118 2

Gear-related 1 1 1 0 145 2

Unknown 14 1 2 0

Total 38 100 128 100 1,456 100 6,182 100

a Accident aircraft were identified using the Safety Boardís aviation accident/incident database. Data for the period 

1995ñ1998 were included in this analysis. Some percent columns may not add to 100 because of rounding.

Table 14. Public versus general aviation accident aircraft by first occurrence, rotorcraft only.a

Public rotorcraft General aviation rotorcraft

First occurrence Fatal

Percent 

total

NonfatalPercent 

total Fatal

Percent 

total

NonfatalPercent 

total

Collision:

In-flight 3 21 10 16 30 30 94 18

On ground/water 5 8 12 2

Noncollision:

In-flight 8 57 17 27 47 47 169 32

Power-related 3 21 22 34 18 18 160 30

On ground/water 7 11 3 3 80 15

Miscellaneous 2 3 1 1 15 3

Gear-related 1 2 2 0

Unknown 

Total 14 100 64 100 99 100 532 100

a Accident aircraft were identified using the Safety Boardís aviation accident/incident database. Data for the period 

1995ñ1998 were included in this analysis. Some percent columns may not add to 100 as a result of rounding error.

Accident Characteristics
29 Safety Study

Phase of Flight

Staff also examined the frequency with which public aircraft accident sequences

began in different phases of flight (see table 16). Staff observed the following significant

differences between the two sectors. Both fatal and nonfatal public aircraft accidents were

more likely than GA accidents to have occurred during a maneuvering phase of flight (42

percent of public aircraft versus 26 percent for GA aircraft involved in fatal accidents, 20

percent for public aircraft versus 10 percent for GA aircraft for nonfatal accidents).

Table 15. Public versus general aviation accident aircraft by first occurrence, fixedwing aircraft only.a

Public fixed-wing aircraft General aviation fixed-wing aircraft

First occurrence Fatal

Percent 

total

NonfatalPercent 

total Fatal

Percent 

total

NonfatalPercent 

total

Collision:

In-flight 15 63 6 10 390 30 641 12

On ground/water 2 3 4 0 398 7

Noncollision:

In-flight 7 29 9 15 633 48 901 17

Power-related 2 8 15 25 227 17 1,783 33

On ground/water 27 44 28 2 1,471 27

Miscellaneous 2 3 19 1 78 1

Gear-related 1 0 142 3

Unknown 14 1 2 0

Total 24 100 61 100 1,316 100 5,416 100

a Accident aircraft were identified using the Safety Boardís aviation accident/incident database. Data for the period 

1995ñ1998 were included in this analysis. Some percent columns may not add to 100 because of rounding.

Accident Characteristics
30 Safety Study

Again, staff performed the same analysis after limiting the sample first to

rotorcraft, then to fixed-wing aircraft. Again, sample size and statistical power were

limited. Analyses failed to confirm the same result in these more restricted samples,

although the proportions lay in the same direction (tables 17 and 18).

Table 16. Public versus general aviation accident aircraft by phase of flight for first 

occurrence, all aircraft categories.a

Public aircraft General aviation aircraft

Phase of flight Fatal Percent

Nonfatal Percent Fatal PercentNonfatal Percent

Cruise 12 32 15 12 385 26 869 14

Maneuvering 16 42 26 20 384 26 607 10

Approach 4 11 9 7 228 16 762 12

Takeoff 3 8 22 17 212 15 1,346 22

Climb 1 3 1 1 84 6 160 3

Descent 45 3 148 2

Landing 37 29 34 2 1,892 31

Hover 1 3 9 7 11 1 78 1

Standing 5 4 9 1 71 1

Other 1 1 8 1 6 0

Taxi 4 3 3 0 205 3

Uncontrolled descent 2 0 9 0

Emergency landing 1 0 16 0

Holding 1 0

Unknown 1 3 50 3 12 0

Total 38 100 129 100 1,456 100 6,182 100

a Accident aircraft were identified using the Safety Boardís aviation accident/incident database. Data for the period 

1995ñ1998 were included in this analysis. Some percent columns may not add to 100 because of rounding.

Accident Characteristics
31 Safety Study

Table 17. Public versus general aviation accident aircraft by phase of flight for first 

occurrence, rotorcraft only.a

Public rotorcraft General aviation rotorcraft

Phase of flight Fatal Percent

Nonfatal Percent Fatal PercentNonfatal Percent

Cruise 2 14 10 16 27 27 87 16

Maneuvering 7 50 19 30 34 34 126 24

Approach 1 7 2 3 5 5 44 8

Takeoff 2 14 9 14 9 9 66 12

Climb 1 7 3 3 9 2

Descent 4 4 7 1

Landing 10 16 1 1 91 17

Hover 1 7 9 14 11 11 77 14

Standing 5 8 1 1 14 3

Other 1 0

Taxi 5 1

Uncontrolled descent 4 1

Emergency landing 1 0

Holding

Unknown 4 4

Total 14 100 64 100 99 100 532 100

a Accident aircraft were identified using the Safety Boardís aviation accident/incident database. Data for the period 

1995ñ1998 were included in this analysis. Some percent columns may not add to 100 because of rounding.

Table 18. Public versus general aviation accident aircraft by phase of flight for first 

occurrence, fixed-wing aircraft only.a

Public fixed-wing aircraft General aviation fixed-wing aircraft

Phase of flight Fatal Percent

Nonfatal Percent Fatal PercentNonfatal Percent

Cruise 10 42 5 8 353 27 760 14

Maneuvering 9 38 7 11 339 26 458 8

Approach 3 13 7 11 215 16 676 12

Takeoff 1 4 11 18 197 15 1,233 23

Climb 1 2 76 6 150 3

Descent 40 3 132 2

Landing 26 42 31 2 1,717 32

Hover 1 0

Standing 8 1 53 1

Other 1 2 8 1 5 0

Taxi 4 6 3 0 198 4

Uncontrolled descent 2 0 5 0

Emergency landing 15 0

Holding 1 0

Unknown 1 4 46 3 12 0

Total 24 100 62 100 1,318 100 5,416 100

a Accident aircraft were identified using the Safety Boardís aviation accident/incident database. Data for the period 

1995ñ1998 were included in this analysis. Some percent columns may not add to 100 because of rounding.

Accident Characteristics
32 Safety Study

Causes or Contributing Factors

The proportions of accidents due to the broadest categories of aircraft-related,

environment-related, and pilot-related factors were virtually identical for public and GA

accident aircraft. Accident aircraft counts, grouped by categories of causal factors are

shown in table 19. The most common causes or related factors reported by accident

investigators for both public and GA accident aircraft were pilot-related (83 percent for

fatal public aircraft accidents versus 88 percent for fatal GA accidents), followed by

environment-related and aircraft-related factors.

Table 19. Public versus general aviation cause and contributing factor categories by 

accident severity, all aircraft types.a

Public aircraft General aviation aircraft

Cause/contributing 

factor Fatal

Percent

total Nonfatal

Percent

total Fatal

Percent

total Nonfatal

Percent

total

All aircraft factors: 9 24 39 31 331 23 2,053 34

Propulsion controls 4 11 27 22 199 14 1,463 24

Flight controls 27 2 100 2

Airframe 1 3 1 1 51 4 72 1

Landing gear 7 6 4 0 253 4

Systems 4 11 6 5 65 5 251 4

All environment factors: 17 46 67 54 591 42 2,771 46

Weather 9 24 30 24 404 29 1,223 20

Light conditions 4 11 7 6 170 12 232 4

Object 1 3 12 10 84 6 457 8

Airport facilities 1 3 2 2 12 1 48 1

Terrain or

runway conditions

 7 19 35 28 150 11 1,410 23

All personnel factors: 35 95 106 85 1,353 96 5,150 85

Pilot 31 84 96 77 1,276 90 4,740 78

Others aboard 1 3 4 3 24 2 47 1

Others not aboard 14 38 13 10 179 13 543 9

Accidents with at least 

one known cause/factor

37 100 124 100 1,413 100 6,055 100

a Accident aircraft were identified using the Safety Boardís aviation accident/incident database. Data for the period 

1995ñ1998 were included in this analysis. Percent columns do not add to 100 because more than one category of 

causes or related factors could be counted for a single accident. However, multiple causal factors in a single category 

for a single accident were only counted once.

Accident Characteristics
33 Safety Study

The same analyses were repeated for rotorcraft (table 20) and fixed-wing aircraft

(table 21), with similar results.

Table 20. Public versus general aviation cause and contributing factor categories by 

accident severity, rotorcraft only.a

Public rotorcraft General aviation rotorcraft

Cause/contributing factor Fatal

Percent

total Nonfatal

Percent

total Fatal

Percent

total Nonfatal

Percent

total

All aircraft factors: 6 46 22 35 37 38 207 39

Propulsion controls 3 23 16 25 23 23 155 30

Flight controls 5 5 20 4

Airframe 1 8 3 3 9 2

Landing gear 2 3 7 1

Systems 2 15 6 10 7 7 35 7

All environment factors: 8 62 31 49 36 37 181 34

Weather 3 23 10 16 19 19 64 12

Light conditions 3 23 5 8 11 11 21 4

Object 6 10 8 8 35 7

Airport facilities 1 8 1 2 1 1 2 0

Terrain or

runway conditions

 3 23 17 27 11 11 94 18

All personnel factors: 11 85 49 78 89 91 440 84

Pilot 8 62 41 65 74 76 375 71

Others aboard 4 6 1 1 10 2

Others not aboard 6 46 9 14 27 28 81 15

Accidents with at least one 

known cause/factor

13 100 63 100 98 100 525 100

a Accident aircraft were identified using the Safety Boardís aviation accident/incident database. Data for the period 

1995ñ1998 were included in this analysis. Percent columns do not add to 100 because more than one category of 

causes or related factors could be counted for a single accident. However, multiple causal factors in a single category 

for a single accident were only counted once.

Accident Characteristics
34 Safety Study

Pilot Certification

Accident-involved public aircraft pilots were very different from accidentinvolved GA pilots in terms of pilot certification (table 22). Accident-involved public

aircraft pilots were more highly qualified than accident-involved GA aircraft pilots in that

they were more likely to hold a commercial pilot rating (64 percent for public versus 36

percent for GA) and they were more likely to hold an airline transport pilot rating (24

percent for public versus 12 percent for GA).

Table 21. Public versus general aviation cause and contributing factor categories by 

accident severity, fixed-wing aircraft only.a

Public fixed-wing aircraft General aviation fixed-wing aircraft

Cause/contributing 

factor Fatal

Percent

total Nonfatal

Percent

total Fatal

Percent

total Nonfatal

Percent

total

All aircraft factors: 3 13 16 26 282 22 1,810 34

Propulsion controls 1 4 11 18 173 13 1,301 24

Flight controls 18 1 73 1

Airframe 45 3 56 1

Landing gear 5 8 4 0 246 5

Systems 2 8 56 4 202 4

All environment factors: 9 38 34 56 550 42 2,478 46

Weather 6 25 20 33 380 29 1,083 20

Light conditions 1 4 2 3 159 12 207 4

Object 1 4 5 8 75 6 398 7

Airport facilities 1 2 11 1 46 1

Terrain or

runway conditions

 4 17 17 28 137 10 1,284 24

All personnel factors: 24 100 54 89 1,228 94 4,495 84

Pilot 23 96 52 85 1,168 89 4,167 78

Others aboard 1 4 22 2 27 1

Others not aboard 8 33 4 7 146 11 445 8

Accidents with at least 

one known cause/factor

24 100 61 100 1,310 100 5,359 100

a Accident aircraft were identified using the Safety Boardís aviation accident/incident database. Data for the period 

1995ñ1998 were included in this analysis. Percent columns do not add to 100 because more than one category of 

causes or related factors could be counted for a single accident. However, multiple causal factors in a single category 

for a single accident were only counted once.

Accident Characteristics
35 Safety Study

In addition, accident-involved public aircraft pilots were more likely than

accident-involved GA pilots to hold an instrument rating (78 percent for public versus 50

percent for GA) (table 23).

Table 22. Highest rating for accident-involved pilots-in-command.a

Public aircraft

Pilots-in-command

General aviation aircraft

Pilots-in-command

Highest rating Pilots Percent of pilots Pilots Percent of pilots

Airline transport pilot 41 24 877 12

Commercial 109 64 2,740 36

Private 18 11 3,419 45

Student 1 1 576 8

a Accident aircraft pilots were identified using the Safety Boardís aviation accident/incident database. Figures in this 

table were based on accident data for the period 1995ñ1998.

Table 23. Type of instrument rating for accident involved pilots-in-command.a

Public aircraft

Pilots-in-command

General aviation aircraft

Pilots-in-command

Instrument rating held Pilots Percent of pilots Pilots Percent of pilots

Any instrument rating 135 78 3,918 50

Airplane 114 66 3,628 46

Helicopter 49 28 338 4

No instrument rating 39 22 3,908 50

a Accident-involved pilots were identified using the Safety Boardís aviation accident/incident database. Ratings shown 

for pilots-in-command only. Figures in this table were based on accident data for the period 1995ñ1998.

Accident Characteristics

37 Safety Study

Chapter 5

Analysis

The Safety Board compared the safety of public and civil aircraft by reviewing

safety statistics on aircraft operations since 1993. The Board was hampered by a lack of

available public aircraft activity estimates for years prior to 1996 and by the unreliability

and lack of detail characterizing activity estimates published since that time. As a result,

the Board can only offer tentative conclusions about the relative safety of public and civil

aircraft. A comparison of public and GA aircraft accident rates, based on imprecise FAA

activity estimates, revealed that during the period 1996ñ1999, public aircraft experienced

fewer accidents per flight hour than GA aircraft, but more than aircraft performing

scheduled operations under 14 CFR Part 135 or Part 121.

The Safety Boardís concerns about the reliability and validity of the FAAís public

aircraft activity estimates used to calculate the accident rates in this report are fivefold:

1. The definition of ìpublic useî provided on GA survey forms used to collect the

data for estimating public aircraft flight hours is broader than the statutory

definition for public aircraft.

2. Accurate reporting of public use flight hours and purpose-of-flight information

depends on the ability of aircraft owners, who may be one or more steps

removed from the actual flying of the aircraft, to obtain detailed information

about the aircraftís flying activities during the previous year.

3. Accurate public and civil aircraft flight hour estimates depend on the currency

and accuracy of the FAA Civil Aviation Registry. However, it can be

conservatively estimated that about 19 percent of registry records are outdated

or incorrect, impeding flight activity sampling and estimation processes.

4. Too few public aircraft are sampled as part of the GA survey; as a result,

sampling error is much higher for estimates of public aircraft flight hours than

estimates for GA flying conducted for personal or business reasons.

5. The GA survey questionnaire is designed in a way that prevents the reporting

or estimation of public aircraft flight hours according to purpose of flight.

The records and processes used to generate the FAAís annual flight hour estimates

for public and civil aircraft are in need of several improvements.

First, because FAA estimates of public aircraft flight hours are based on a set of

aircraft operations broader than those meeting the statutory definition of public aircraft

operations, the FAA should revise the GA survey data collection system to more clearly

distinguish between government aircraft operations that qualify for statutory public

aircraft status and those that do not. This will allow the Safety Board and other

government organizations to calculate more accurate public aircraft accident rates.
38 Safety Study

Second, the FAA should identify and implement methods of checking the accuracy

of the information collected using the GA survey. The FAAís inability to sample as much

as a quarter of the active GA fleet raises serious questions about the organizationís ability

to accurately estimate GA or public aircraft flight activity using a sample survey

approach.33 The reliance on aircraft owners to provide the desired information is subject to

a number of weaknesses discussed in chapter 2. Although surveying owners may be the

most practical means available for collecting nonairline flight activity data, the FAA

should identify and implement methods independent of the GA survey that can be used to

check the accuracy of nonairline flight hour estimates.

Third, the FAA should improve the accuracy and currency of the Civil Aviation

Registry. The GADIT committee recently recommended that the FAA obtain address

verification every 3 years by requiring a response to the triennial aircraft registration form,

regardless of any change in an ownerís registration information. Although this would

represent a positive step, the Safety Board believes that it is insufficient to ensure the

currency of the registry. It would do nothing to improve the 28,000 aircraft records that

are known to contain outdated owner contact information. These individuals no longer

receive triennial registration report forms because the FAA cannot contact them. The

registryís effort to contact aircraft owners who have submitted a change of address form to

the USPS and request updated contact information also represents a positive step, but the

vast majority of owners so contacted fail to respond to the FAA. For these reasons, the

Board is concerned that owner contact information in the registry will continue to

deteriorate, further hampering the FAAís ability to estimate annual nonairline flight

activity. The FAA should implement a program that will (a) measure and track the

currency of aircraft owner contact information in the registry and (b) systematically

improve the currency of this information in a measurable way.

Fourth, the FAA should reduce the sampling error associated with estimates of

public use flying activity. Estimates for public use flying activity are currently less precise

than estimates for major categories of GA activity (for example, business, personal,

instructional, and so on). This results from differences in the number of aircraft sampled.

This situation can be improved by sampling an increased number of aircraft that perform

public aircraft operations. The FAA should revise the sampling strategy of the GA survey

to achieve a precision of public use flight hour estimates (in terms of sampling error) that

is equivalent to the precision of estimates for personal, business, or corporate

subcategories of GA.

Finally, the FAA should revise the GA survey form so that operators can report

public aircraft flight hours by purpose of flight. Purpose-of-flight categories should be

mutually exclusive. Current categories mix administrative purposes of flight with flying

activities. The FAA should develop a new reporting matrix on the GA survey form that

separates the administrative purpose of flight (for example, personal, business, corporate,

regional, air taxi, air tours, sightseeing, public use, air medical services, search and rescue,

33 This figureóone quarter of the active fleetóincludes known outdated or inaccurate records

combined with the number of estimated outdated or inaccurate records yet to be verified. The figure is given

in a memo written by the FAAís contractor for survey data analysis, PA Consulting, dated March 26, 2001.

Analysis
39 Safety Study

and so on) from the actual flying activity performed (for example, transport of passengers,

flight instruction, aerial observation, aerial application, external load, and so on). The

FAA should incorporate these changes in published flight hour estimates as well.

In addition, the FAA should revise the GA survey so that aircraft owners can

report public aircraft flight hours according to the level of government served (Federal,

State, or local) within each purpose-of-flight category. This will make it possible to

compare the safety of public aircraft operations sponsored by different levels of

government.

An additional issue of interest involves the FAAís inclusion of CAP flight hours in

annual public use flight activity estimates. CAP flight hours made up about 7 percent of

the FAAís 1999 estimate of public use flight hours despite the fact that CAP flights are not

considered public aircraft operations under current law. The inclusion of these hours

inflates the FAAís annual estimate of public use flight activity. The CAP returned 14

surveys to the FAA for the 1999 GA survey. On these surveys, CAP personnel classified a

total of 1,263 aircraft flight hours as public use. Based on the FAAís sample weighting

factors for these aircraft, these surveys contributed 75,324 flight hours (7 percent) to the

FAAís overall 1999 estimate of public use flight hours. The FAA should remove CAP

flight hours from future estimates of public aircraft activity so that the figures are

consistent with the current statutory definition of public aircraft.

With respect to Federal public aircraft activity data, the Safety Board applauds the

steps the GSA has taken to improve collection of Federal aircraft activity data. Although

Federal government operators have been reporting aircraft flight hours to the GSA in

recent years, these data were reported by each agency only in an aggregate fashion. The

GSAís new automated data entry and analysis system, FAIRS, should provide easily

accessible activity and cost data at the level of specific aircraft with added ability to total

flight hours according to mission characteristics and other factors. This system will

provide a complete set of data describing Federal aircraft operations for 2001 and

subsequent years. The FAIRS system, currently being deployed by the GSA, should

enhance the GSAís ability to monitor Federal government aircraft activity and should

allow the GSA to provide better information to other Federal agencies, including the

Safety Board. The Safety Board encourages the GSA to finish the implementation of this

system and take steps to ensure that it will function as intended. The Safety Board believes

that the GSA should collect and maintain aircraft flight hour data from Federal agencies in

such a way that it is possible to distinguish Federal public aircraft flight operations from

other Federal government-sponsored flight operations.

A final concern involves the parallel development of activity data collection

systems at the FAA and the GSA. It would be useful to compare the safety of Federal

public aircraft versus other aircraft engaged in the same kinds of flying activities.

However, the development of separate, independent activity data collection systems by

the FAA and the GSA is leading to the collection of flight hour data in terms of

incompatible categories of purpose of flight. This will make it difficult, if not impossible,

to compare accident rates for Federal public aircraft versus other public aircraft for

Analysis
40 Safety Study

specific kinds of flying activities. The GSA and the FAA should define purpose-of-flight

categories in the FAIRS that correspond to purpose-of-flight categories in the GA survey.

The Safety Board last addressed deficiencies in nonairline flight activity estimates

in its 1979 study, Single-Engine Fixed-Wing General Aviation Accidents.

34 In that study,

the Safety Board analyzed accident rates for specific models of GA aircraft.35 The analyses revealed large differences in model-specific accident rates, but the studyís authors

could not control for aircraft-specific differences in terms of pilot characteristics, region,

or purpose of flight. This led to difficulty interpreting differences in model-specific accident rates. As a result, the Safety Board recommended that the FAA collect more detailed

GA activity data so that more specific rates could be calculated and the safety performance of different aircraft types could be more carefully evaluated. The Boardís recommendation was phrased as follows:

Generate, through a stratified sampling of general aviation pilots, the date,

duration, aircraft make and model, the geographical location of the flight, and the

flight time in IFR, high density altitude, and wind conditions, all on a per flight

basis; the data collected should include the pilotís total time, time in each type

aircraft flown, age, occupation, certificate, and medical waivers. (A-79-44)

The FAA formed a committee in 1980 which sought to identify human

factors/exposure data and the alternatives to acquiring such data. However, after the

Safety Board attended several meetings with the FAA, it became clear that the FAA was

not likely to take meaningful action related to recommendation A-79-44. The

recommendation was classified ìClosed-Unacceptable Actionî by the Safety Board on

December 1, 1986. However, detailed, accurate statistics describing flight activity remain

crucial for monitoring the safety of general aviation and for monitoring the safety of air

taxi and public aircraft operations as well.

34 National Transportation Safety Board, Single-Engine Fixed Wing General Aviation Accidents,

Aviation Special Study, NTSB/AAS-79/01 (Washington, DC: NTSB, 1979).

35 This would not be possible today, because the FAA no longer collects flight hours for specific aircraft

models.

Analysis
41 Safety Study

Conclusions

As a result of this safety study, the National Transportation Safety Board draws the

following conclusions:

1. A comparison of public and general aviation aircraft accident rates, based on

imprecise FAA activity estimates, revealed that, during the period 1996ñ1999, public

aircraft experienced fewer accidents per flight hour than general aviation aircraft, but

more than aircraft performing scheduled operations under 14 CFR Part 135 or Part

121.

2. About 64 percent of public accident aircraft were engaged in local flying, compared

to only 48 percent of general aviation accident aircraft. Furthermore, local public

aircraft accident flights were more likely than local general aviation accident flights

to have crashed at an off-airport location.

3. A higher proportion of fatal public aircraft accidents began with an in-flight collision

(46 percent for public aircraft versus 29 percent for general aviation aircraft).

4. Both fatal and nonfatal public aircraft accidents were more likely than general

aviation accidents to have occurred during a maneuvering phase of flight (42 percent

of public aircraft versus 26 percent for general aviation aircraft involved in fatal

accidents, 20 percent for public aircraft versus 10 percent for general aviation aircraft

for nonfatal accidents).

5. The most common causes or related factors reported by accident investigators for

both public and general aviation accident aircraft were pilot-related (83 percent for

fatal public aircraft accidents versus 88 percent for fatal general aviation accidents),

followed by environment-related and aircraft-related factors.

6. Accident-involved public aircraft pilots were more highly qualified than accidentinvolved general aviation aircraft pilots in that they were more likely to hold a

commercial pilot rating (64 percent for public versus 36 percent for general aviation)

and they were more likely to hold an airline transport pilot rating (24 percent for

public versus 12 percent for general aviation).

7. Accident-involved public aircraft pilots were more likely than accident-involved

general aviation pilots to hold an instrument rating (78 percent for public versus 50

percent for general aviation).

8. The definition of ìpublic useî provided on General Aviation and Air Taxi Activity

Survey forms used to collect the data for estimating public aircraft flight hours is

broader than the statutory definition for public aircraft.
42 Safety Study

9. Accurate reporting of public use flight hours and purpose-of-flight information

depends on the ability of aircraft owners, who may be one or more steps removed

from the actual flying of the aircraft, to obtain detailed information about the

aircraftís flying activities during the previous year.

10. Accurate public and civil aircraft flight hour estimates depend on the currency and

accuracy of the FAA Civil Aviation Registry. However, it can be conservatively

estimated that about 19 percent of registry records are outdated or incorrect, impeding

flight activity sampling and estimation processes.

11. Too few public aircraft are sampled as part of the General Aviation and Air Taxi

Activity Survey; as a result, sampling error is much higher for estimates of public

aircraft flight hours than for estimates of general aviation flying conducted for

personal or business reasons.

12. The General Aviation and Air Taxi Activity Survey questionnaire is designed in a

way that prevents the reporting or estimation of public aircraft flight hours according

to purpose of flight.

13. Civil Air Patrol flight hours made up about 7 percent of the FAAís 1999 overall

estimate of public use flight hours despite the fact that CAP flights are not considered

public aircraft operations under current statutes, inflating the FAAís annual estimate

of public use flight activity.

14. The Federal Aviation Interactive Reporting System, currently being deployed by the

General Services Administration (GSA), should enhance the GSAís ability to monitor

Federal government aircraft activity and should allow the GSA to provide better

information to other Federal agencies, including the Safety Board.

15. The development of separate, independent activity data collection systems by the

Federal Aviation Administration and the General Services Administration is leading

to the collection of flight hour data in terms of incompatible categories of purpose of

flight. This will make it difficult, if not impossible to compare accident rates for

Federal public aircraft versus other public aircraft for specific kinds of flying

activities.

Conclusions
43 Safety Study

Recommendations

As a result of this safety study, the National Transportation Safety Board makes

the following safety recommendations:

To the Federal Aviation Administration:

Revise the General Aviation and Air Taxi Activity Survey data collection

system to more clearly distinguish between government aircraft operations

that qualify for statutory public aircraft status and those that do not. (A-01-

73)

Identify and implement methods independent of the General Aviation and

Air Taxi Activity Survey that can be used to check the accuracy of

nonairline flight hour estimates. (A-01-74)

Implement a program that will (a) measure and track the currency of

aircraft owner contact information in the Civil Aircraft Registry and (b)

systematically improve the currency of this information in a measurable

way. (A-01-75)

Revise the sampling strategy of the General Aviation and Air Taxi Activity

Survey to achieve a precision of public use flight hour estimates (in terms

of sampling error) that is equivalent to the precision of estimates for

personal, business, or corporate subcategories of general aviation. (A-01-

76)

Develop a new reporting matrix on the General Aviation and Air Taxi

Activity Survey form that separates the administrative purpose of flight

(for example, personal, business, corporate, regional, air taxi, air tours,

sightseeing, public use, air medical services, search and rescue, and so on)

from the actual flying activity performed (for example, transport of

passengers, flight instruction, aerial observation, aerial application,

external load, and so on). Incorporate these changes in published flight

hour estimates. (A-01-77)

Revise the General Aviation and Air Taxi Activity Survey form so that

aircraft owners can report public aircraft flight hours according to the level

of government served (Federal, State, or local) within each purpose-offlight category. (A-01-78)

Remove Civil Air Patrol flight hours from future estimates of public

aircraft activity so that the figures are consistent with the current statutory

definition of public aircraft. (A-01-79)
44 Safety Study

In cooperation with the General Services Administration, define purposeof-flight categories in the Federal Aviation Interactive Reporting System

that correspond to purpose-of-flight categories in the General Aviation and

Air Taxi Activity Survey. (A-01-80)

To the U.S. General Services Administration:

Collect and maintain aircraft flight hour data from Federal agencies in such

a way that it is possible to distinguish Federal public aircraft flight

operations from other Federal government-sponsored flight operations. (A01-81)

In cooperation with the Federal Aviation Administration, define purposeof-flight categories in the Federal Aviation Interactive Reporting System

that correspond to purpose-of-flight categories in the General Aviation and

Air Taxi Activity Survey. (A-01-82)

By the National Transportation Safety Board

MARION C. BLAKEY

Chairman

CAROL J. CARMODY

Vice Chairman

JOHN A. HAMMERSCHMIDT

Member 

JOHN J. GOGLIA

Member

GEORGE W. BLACK, JR.

Member

Adopted: October 23, 2001

Recommendations
45 Safety Study

Appendix A

Partial List of Federal Aviation Safety Regulations

That Do Not Apply to Public Aircraft

14 CFR Description

43 Maintenance, preventive maintenance, rebuilding, and

alteration

61.5 FAA pilot and medical certification requirements

91.7 Aircraft airworthiness requirement standards

91.8 Aircraft flight manual, marking, and placard requirements

91.15 Dropping of objects requirements

91.17 Prohibition of operation of aircraft by crewmembers who might

have used alcohol or drugs within certain time frames and

circumstances

91.103 Certain preflight actions

91.105 Requirement of flight crewmembers to be at duty stations

91.107 Use of safety belts, shoulder harnesses, etc.

91.167 Fuel requirements for IFR flight

91.203 Requirements for airworthiness and registration certificates and

presence on board aircraft

91.207 Emergency locator transmitters

91.311 Towing of things by aircraft

91.401 Aircraft maintenance requirements
46 Safety Study

Appendix B

Statutory Definition of ìPublic Aircraftî

Title 49 United States Code, Section 40102(a)(37)

(as amended by Public Law 106-181):

ìpublic aircraftî means any of the following:

(A) Except with respect to an aircraft described in subparagraph (E), an aircraft used only

for the United States Government, except as provided in section 40125(b).

(B) An aircraft owned by the Government and operated by any person for purposes related

to crew training, equipment development, or demonstration, except as provided in section

40125(b).

(C) An aircraft owned and operated by the government of a State, the District of

Columbia, or a territory or possession of the United States or a political subdivision of one

of these governments, except as provided in section 40125(b).

(D) An aircraft exclusively leased for at least 90 continuous days by the government of a

State, the District of Columbia, or a territory or possession of the United States or a

political subdivision of one of these governments, except as provided in section 40125(b).

(E) An aircraft owned or operated by the armed forces or chartered to provide

transportation to the armed forces under the conditions specified by section 40125(c).

Title 49 United States Code, Section 40125:

ß40125. Qualifications for public aircraft status 

(a) Definitions. In this section, the following definitions apply:

(1) Commercial purposes. The term ìcommercial purposesî means the 

transportation of persons or property for compensation or hire, but does not 

include the operation of an aircraft by the armed forces for reimbursement 

when that reimbursement is required by any Federal statute, regulation, or 

directive, in effect on November 1, 1999, or by one government on behalf 

of another government under a cost reimbursement agreement if the 

government on whose behalf the operation is conducted certifies to the 

Administrator of the Federal Aviation Administration that the operation is 

necessary to respond to a significant and imminent threat to life or property 

(including natural resources) and that no service by a private operator is 

reasonably available to meet the threat.
47 Safety Study

(2) Governmental function. The term ìgovernmental functionî means an 

activity undertaken by a government, such as national defense, intelligence 

missions, firefighting, search and rescue, law enforcement (including 

transport of prisoners, detainees, and illegal aliens), aeronautical research, 

or biological or geological resource management.

(3) Qualified non-crewmember. The term ìqualified non-crewmemberî

means an individual, other than a member of the crew, aboard an aircraft--

(A) operated by the armed forces or an intelligence agency of the United 

States Government; or

(B) whose presence is required to perform, or is associated with the performance of, a governmental function.

(4) Armed forces. The term ìarmed forcesî has the meaning given such

term by section 101 of title 10.

(b) Aircraft owned by governments. An aircraft described in subparagraph (A),

(B), (C), or (D) of section 40102(a)(37) does not qualify as a public aircraft under such

section when the aircraft is used for commercial purposes or to carry an individual other

than a crewmember or a qualified non-crewmember.

(c) Aircraft owned or operated by the Armed Forces. 

(1) In general. Subject to paragraph (2), an aircraft described in section

40102(a)(37)(E) qualifies as a public aircraft if--

(A) the aircraft is operated in accordance with title 10;

(B) the aircraft is operated in the performance of a governmental function 

under title 14, 31, 32, or 50 and the aircraft is not used for commercial purposes; or

(C) the aircraft is chartered to provide transportation to the armed forces 

and the Secretary of Defense (or the Secretary of the department in which 

the Coast Guard is operating) designates the operation of the aircraft as 

being required in the national interest.

(2) Limitation. An aircraft that meets the criteria set forth in paragraph (1) 

and that is owned or operated by the National Guard of a State, the District 

of Columbia, or any territory or possession of the United States, qualifies 

as a public aircraft only to the extent that it is operated under the direct 

control of the Department of Defense.

Appendix B
48 Safety Study

Appendix C

Effect On the Public Aircraft Accident Rate

Of Including Civil Air Patrol Accidents

The Safety Boardís public aircraft accident set included 24 Civil Air Patrol (CAP)

accidents. Staff chose to include these accidents in the sample despite the fact that CAP

aircraft are owned by a private corporation and CAP flights are not considered public

aircraft operations under current law. This decision was made after staff learned that a

large number of CAP flight hours are included in the FAAís public use flight hour

estimates.

The CAP returned 14 surveys to the FAA for the 1999 General Aviation and Air

Taxi Activity Survey. On these surveys, CAP personnel classified a total of 1,263 aircraft

flight hours as public use. Based on the FAAís sample weighting factors for these aircraft,

these surveys contributed 75,324 flight hours (7 percent) to the FAAís overall 1999

estimate of public use flight hours. The number of CAP hours included in earlier estimates

could not be calculated. In order to avoid a bias that would result from excluding CAP

aircraft from the accident sample but leaving CAP flight hours in the activity estimate,

staff decided to leave CAP accidents in the 1993ñ2000 public aircraft accident sample.

Including CAP data probably had a negligible effect on the overall public aircraft

accident rate. Thirteen CAP accidents were reported to the Safety Board between 1996

and 1999, an average of around 3 per year. A CAP accident rate can be estimated under

the assumption that annual CAP flight activity was stable during the period 1996ñ1999

and that a consistent proportion of this flight activity was designated public use by CAP

personnel who returned GA surveys. Based on these assumptions, staff calculated an

annual CAP accident rate of 4.31 per 100,000 flight hours, which is only slightly higher

than the overall public aircraft accident rate (3.66). Furthermore, CAP data contributed a

very small proportion of the accidents (7.6 percent) and flight hours (7 percent) used to

calculate the overall public aircraft accident rate, meaning that this slight difference had

very little influence on the overall figure. For these reasons, staff believe that the inclusion

of CAP data had a negligible effect on the overall public use accident rate presented in this

report.
49 Safety Study

Appendix D

Selected Portions of 14 CFR Part 47

Describing Aircraft Registration Requirements

ß47.45 Change of address.

Within 30 days after any change in his permanent mailing address, the holder of a 

Certificate of Aircraft Registration for an aircraft shall notify the FAA Aircraft Registry of 

his new address. A revised Certificate of Aircraft Registration is then issued, without 

charge.

ß47.51 Triennial aircraft registration report.

(a) Unless one of the registration activities listed in paragraph (b) of this section 

has occurred within the preceding 36 calendar months, the holder of each Certificate of 

Aircraft Registration issued under this subpart shall submit, on the form provided by the 

FAA Aircraft Registry and in the manner described in paragraph (c) of this section, a 

Triennial Aircraft Registration Report, certifying--

(1) The current identification number (registration mark) assigned to the aircraft;

(2) The name and permanent mailing address of the certificate holder;

(3) The name of the manufacturer of the aircraft and its model and serial number;

(4) Whether the certificate holder is--

(i) A citizen of the United States;

(ii) An individual citizen of a foreign country who has lawfully been admitted for permanent residence in the United States; or

(iii) A corporation (other than a corporation which is a citizen of the United 

States) lawfully organized and doing business under the laws of the United 

States or any State thereof; and

(5) Whether the aircraft is currently registered under the laws of any foreign country.

(b) The FAA Aircraft Registry will forward a Triennial Aircraft Registration 

Report to each holder of a Certificate of Aircraft Registration whenever 36 months has 

expired since the latest of the following registration activities occurred with respect to the 

certificate holder's aircraft:
50 Safety Study

(1) The submission of an Application for Aircraft Registration.

(2) The submission of a report or statement required by ß47.9(f).

(3) The filing of a notice of change of permanent mailing address.

(4) The filing of an application for a duplicate Certificate of Aircraft Registration.

(5) The filing of an application for a change of aircraft identification number.

(6) The submission of an Aircraft Registration Eligibility, Identification, and 

Activity Report, Part 1, AC Form 8050-73, under former ß47.44.

(7) The submission of a Triennial Aircraft Registration Report under this section.

(c) The holder of the Certificate of Aircraft Registration shall return the Triennial 

Aircraft Registration Report to the FAA Aircraft Registry within 60 days after issuance by 

the FAA Aircraft Registry. The report must be dated, legibly executed, and signed by the 

certificate holder in the manner prescribed by ß47.13, except that any co-owner may sign 

for all co-owners.

(d) Refusal or failure to submit the Triennial Aircraft Registration Report with the 

information required by this section may be cause for suspension or revocation of the 

Certificate of Aircraft Registration in accordance with Part 13 of this chapter.

Appendix D