Title 48, Chapter 5, Section 540
As used in this article, the term:
(1) "Operated," "operating," or "operation" means landings or
takeoffs of aircraft by any airline company.
(2) "Plane hours" means, for each type and model of aircraft, all
hours in flight and all hours on the ground including, but not
limited to, ground and air time associated with overhaul,
maintenance, flight testing, and training.