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Annual Review of Aircraft Accident Data
U.S. General Aviation, Calendar Year 1999

NTSB Number NTSB/ARC-02/03
NTIS Number PB2002-109241
PDF Document(1.8 MB)

Introduction

Purpose of the Annual Review

The 1999 Annual Review of Aircraft Accident Data: U.S. Air Carrier Operations presents a statistical compilation and review of accidents that occurred in 1999 involving aircraft operated by U.S. air carriers.  In addition to providing accident statistics for 1999, the review also includes general economic and aviation indicators that may have influenced aircraft activity for 1999 as well as contextual accident data from several years preceding the reporting period.

Which Aircraft Are Included in this Review?

This review covers accidents involving aircraft operated by U.S. air carriers under Title 14, Parts 121 and 135, of the Code of Federal Regulations (CFR).  Air carriers are generally defined as operators that fly aircraft in revenue service.  Title 14, also known as the Federal Aviation Regulations (FARs), describes operating requirements in Part 121 and Part 135.  Briefly stated, Part 121 applies to major airlines and cargo carriers that fly large transport-category aircraft while Part 135 applies to commercial air carriers commonly referred to as commuter airlines (i.e., scheduled Part 135) and air taxis (i.e., nonscheduled Part 135).

In March 1997, the definition of Part 121 operations changed.  Prior to the change, scheduled aircraft with 30 or more seats were operated under Part 121 and those with less than 30 seats were operated under Part 135.  After the change, scheduled aircraft with 10 or more seats were classified as Part 121 operations; therefore, since 1997, most carriers that once were popularly known as “commuters” now operate under Part 121.

In this review, the presentation of data for scheduled and nonscheduled Part 135 operations is separated due to the distinct operating characteristics of these groups.  According to 14 CFR 119.3, a scheduled operation refers to, “any common carriage passenger-carrying operation for compensation or hire conducted by an air carrier or commercial operator for which the certificate holder or its representative offers in advance the departure location, departure time, and arrival location.”

By contrast, a nonscheduled operation refers to, “any operation for compensation or hire that is one of the following:

(1) Passenger-carrying operations conducted as a public charter under Part 380 of this title or any operations in which the departure time, departure location, and arrival location are specifically negotiated with the customer or the customer’s representative that are any of the following types of operations:

 (i) Common carriage operations conducted with airplanes, including turbo-  jet-powered airplanes, having a passenger-seat configuration of 30 seats or   fewer, excluding each crewmember seat, and a payload capacity of 7,500   pounds or less, except that operations using a specific airplane that is also   used in domestic or flag operations and that is so listed in the operations   specifications as required by Sec. 119.49(a)(4) for those operations are   considered supplemental operations;
(ii) Noncommon or private carriage operations conducted with airplanes having a passenger-seat configuration of less than 20 seats, excluding each crewmember seat, and a payload capacity of less than 6,000 pounds; or
(iii) Any rotorcraft operation.
(2) Scheduled passenger-carrying operations conducted with one of the following types of aircraft with a frequency of operations of less than five round trips per week on at least one route between two or more points according to the published flight schedules:
(i) Airplanes, other than turbojet powered airplanes, having a maximum passenger-seat configuration of 9 seats or less, excluding each crewmember seat, and a maximum payload capacity of 7,500 pounds or less; or
(ii) Rotorcraft.
(3) All-cargo operations conducted with airplanes having a payload capacity of 7,500 pounds or less, or with rotorcraft.”

In addition to the regulatory differences between scheduled and nonscheduled Part 135 operations, there are other general characteristics that distinguish these two groups.  Carriers operating under scheduled Part 135 typically fly aircraft with single/twin turbine engines or single/twin reciprocating engines.  They are more likely to fly short routes and a majority of operators are based in Alaska.  By contrast, nonscheduled Part 135 operators are more evenly distributed throughout the United States and represent a diverse group, ranging from operators with one small aircraft to those with multiple large corporate jets.

While there are many differences in the operating rules for scheduled and nonscheduled Part 135 operations, there are fewer factors that differentiate the operating rules for scheduled and nonscheduled Part 121 operators.  In addition, while activity data for scheduled and nonscheduled Part 135 operators are collected using different methods, all Part 121 operations are required to report activity data on a regular basis. Therefore, data for scheduled and nonscheduled Part 121 operations have been combined for analysis.

Which Aircraft Are Not Included in this Review?

• General aviation aircraft (A separate review, published annually by the NTSB, summarizes accident statistics for these aircraft);
• Military aircraft;
• Foreign-operated aircraft;
• Certain public use aircraft as defined in 49 CFR 830.5;
• Ultralight vehicles;
• Experimental aircraft; and
• Commercial space launches.

Organization of the Annual Review

The 1999 Annual Review is organized into three parts:
1. The first part presents an overview of the state of the economy and the aviation industry in 1999 as well as contextual statistics from previous years.  It also includes a historical overview of both the number of accidents and accident rates between the years 1990 and 1999.

2. The second part investigates trends over the past 10 years in terms of various factors such as the types of flight, levels of aircraft damage, and level of human injury.  This part is divided into separate sections for Part 121, scheduled Part 135, and nonscheduled Part 135 aircraft accidents.

3. The last part focuses on accidents that occurred during the 1999 calendar year and their circumstances.  This part is divided into subsections for Part 121 and Part 135.  Part 135 is divided further to address scheduled and nonscheduled Part 135 operations.

Much of the information in the Annual Review is presented in graphical form.   For readers who wish to view the data in a tabular form or to manipulate the data used in the report, the data set is available online at <http://www.ntsb.gov/aviation/Stats.htm>.

The NTSB Investigative Process

The NTSB investigates every civil aviation accident that occurs in the United States.  It also provides investigators to serve as U.S. Accredited Representatives as specified in international treaties for aviation accidents overseas involving U.S.-registered aircraft, or involving aircraft or major components of U.S. manufacture.1   Investigations are conducted from NTSB Headquarters in Washington, D.C., or from one of the ten regional  offices in the United States (see Appendix A).

Note that there is a distinction between the population of accidents investigated by the NTSB and those that are included in the Annual Review.  While the NTSB investigates all civil aviation accidents that occur on U.S. soil (including domestic and foreign operators), the Annual Review describes accidents that occurred among U.S.-operated aircraft in all parts of the world.

The NTSB Aviation Accident/Incident Database

The NTSB is responsible for maintaining the government’s database on civil aviation accidents.  The NTSB Accident/Incident Database is the official repository of aviation accident data and causal factors.  The database was established in 1962 (by the NTSB’s predecessor agency, the Civil Aeronautics Board) and approximately 2,000 new event records are added each year.  For each record, there are over 650 fields of data concerning the aircraft, environment, engines, injuries, sequence of accident events and other topics.  The NTSB Accident/Incident Database is available to the public at <ftp://www.ntsb.gov/avdata/>.  Alternately, there is a Database Query tool at <http://www.ntsb.gov/ntsb/query.asp#query_start> that allows users to search for sets of accidents using commonly known information such as date, location, and category of aircraft.

The NTSB database is primarily composed of aircraft accidents.  An “accident” is defined in 49 CFR 830.2 as, “an occurrence associated with the operation of an aircraft which takes place between the time any person boards the aircraft with the intention of flight and all such persons have disembarked, and in which any person suffers death1  or serious injury,2  or in which the aircraft receives substantial damage. ”3  The database also contains several aviation “incidents,” defined in 49 CFR 830.2 as, “occurrences other than accidents that are associated with the operation of an aircraft and that affect or could affect the safety of operations.”

Accident investigators use the NTSB’s Accident Data Management System (ADMS) software to enter data into the Accident/Incident Database.   Within about a week of the event, a Preliminary Report, containing limited information such as date, location, aircraft operator, and type of aircraft, becomes available.  A Factual Report with additional information concerning the occurrence is available within a few months.  See Appendix B for documents showing the information available in Preliminary and Factual Reports.  A Final Report, which includes a statement of the probable cause and other contributing factors, is issued after the investigation has been completed.  Five presidential appointees serving as Members of the Safety Board, or their delegates, must approve official statements dealing with the probable cause of an accident.  Complete records are made available to the public only after this approval has been granted.

In determining the probable cause(s) of an accident, all facts, conditions and circumstances are considered.  Within each accident occurence, any information that contributes to the explanation of that event is identified as a “finding” and may be further designated as either a “cause” or “factor.”  The term “factor” is used to describe situations or circumstances that contributed to the accident cause.  The details of probable cause are coded as the combination of all causes, factors, and findings associated with the accident.  Just as accidents often include a series of occurrences, the reasons why these occurrences lead to an accident may be the combination of multiple causes and factors.  For this reason, a single accident record may include multiple causes and factors.
 

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1 For more detailed information about the criteria for NTSB investigation of an aviation accident or incident, see Title 49 Code of Federal Regulations 831.2.
2 “Fatal injury” means any injury that results in death within 30 days of the accident.
3 “Serious injury” means any injury which: (1) requires hospitalization for more than 48 hours, commencing within 7 days from the date the injury was received; (2) results in a fracture of any bone (except simple fractures of fingers, toes, or nose); (3) causes severe hemorrhages, nerve, muscle, or tendon damage; (4) involves any internal organ; or (5) involves second- or third-degree burns, or any burns affecting more than 5 percent of the body surface.
4 “Substantial damage” means damage or failure which adversely affects the structural strength, performance, or flight characteristics of the aircraft, and which would normally require major repair or replacement of the affected component. Engine failure or damage limited to an engine if only one engine fails or is damaged, bent fairings or cowling, dented skin, small punctured holes in the skin or fabric, ground damage to rotor or propeller blades, and damage to landing gear, wheels, tires, flaps, engine accessories, brakes, or wingtips are not considered “substantial damage” for the purpose of this part.
 
 
 

 
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