A flight for the purpose of: returning an aircraft to base, delivering an aircraft from one location to another, or moving an aircraft to and from a maintenance base. They do not carry revenue passengers.

Actual height above the surface of the earth, either land or water.

Civil aircraft operated in accordance with 14 CFR 91, 121, or 135 for the mutual benefit of DOI and the affiliated party at no cost to DOI.

An AMD-approved aircraft that is available for Intermittent, short-term use under an AMD Basic Ordering Agreement (BOA). Orders for use of agreement aircraft are subject to the small purchase limitation established under the Federal Acquisition Regulations unless otherwise authorized by the Contracting Officer.

The term "aircraft" is used to refer to both airplanes and helicopters.

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 death or serious injury, or in which the aircraft receives substantial damage.

Obtaining an aircraft through either purchase or transfer (excess), or through lease, rental or loan, the operating cost of which can reasonably be expected to exceed $25,000 per year. (Any aircraft secured on a fully vendor operated basis is specifically excluded from this definition.)

An objective determination is made by the first line supervisor that an additional crewmember is required to be on board the aircraft to ensure the successful outcome of the mission. (Example: loadmaster accompanying bulk fuel).

A near mid-air collision, intrusion, or violation of airspace rules.

An aircraft used for the dispensing of a substance (normally fire retardant or water) on a wildfire.