The FBI used both terms. I posted earlier where they referred to it as a plane. And while some types of helicopters may qualify as a plane (and some planes can convert to lift/land like a helicopter), most do not meet the requirements of the definition.
[
http://www.britannica.com/technology/airplane]
Airplane, also called
aeroplane or
plane[/url], any of a class of fixed-wing aircraft that is heavier than air, propelled by a screw propeller or a high-velocity jet, and supported by the dynamic reaction of the air against its wings. For an account of the development of the airplane and the advent of civil aviation
[
http://www.britannica.com/technology/helicopter]
Helicopter[/url], aircraft with one or more power-driven horizontal propellers or rotors that enable it to take off and land vertically, to move in any direction, or to remain stationary in the air. Other vertical-flight craft include autogiros, convertiplanes, and V/STOL aircraft of a number of configurations.