* Flight crews, responsible for the operation of the aircraft. Flight crew members include:

* Pilots (Captain and First Officer: some older aircraft also require a Flight Engineer)

* Flight attendants, (led by a purser on larger aircraft)

* In-flight security personnel on some airlines (most notably El Al) Groundcrew, responsible for operations at airports. Ground crew members include:

 * Aerospace and avionics engineers responsible for certifying the aircraft for flight and management of aircraft maintenance