The first step in the development of this standard was to identify and define several critical
terms. The terms are listed here in alphabetical order, and, where possible, the source of the
definition has been identified.
Air Carrier: As defined by the Federal Aviation Administration (FAA), the commercial system of
air transportation consisting of certificated air carriers, air taxis (including commuters),
supplemental air carriers, commercial operators of large aircraft, and air travel clubs.
Air Taxi: As defined by the FAA, a classification of air carriers that transports persons,
property, and mail using small aircraft (under 30 seats or a maximum payload capacity of less
than 3401 kg [7,500 lb]) in accordance with 14 CFR 135.
Airborne Release Fraction (ARF): The coefficient used to estimate the amount of radioactive
material suspended in air as an aerosol and thus available for transport due to physical stresses
from a specific accident.
Aircraft Accident: As defined by the National Transportation Safety Board (NTSB), an
occurrence associated with the operation of an aircraft that takes place between the time any
person boards the aircraft with the intention of flight until such time as all such persons have
disembarked, and in which any person suffers a fatal or serious injury as a result of being in or
upon the aircraft or by direct contact with the aircraft or anything attached thereto, or in which
the aircraft receives substantial damage.
Aircraft Category: The broadest, most general level of classification for aircraft and aviation
used in this standard. There are three categories: (1) commercial aviation, (2) military aviation,
and (3) general aviation.
Aircraft Crash: For the purpose of this standard, any aircraft accident that results in
destruction of or substantial damage to the aircraft. Fatal or serious injury sustained as a
result of the aircraft accident by itself, without related destruction or substantial damage to the
aircraft, does not make an aircraft accident qualify as an aircraft crash.