What is the definition of in-flight for the purposes of a fire?

Question

Reading 49 CFR 830.5 I am trying to determine the definition of "in flight" and "in-flight" used in the Immediation Notification sections 49 CFR 830.5(a)(4) "In-flight fire" and 49 CFR 830.5(a)(5) "Aircraft collision in flight".

In 49 CFR 830.2 “Aircraft accident” is defined as "...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..." which is a possible answer but this section is very specific to accidents and does not mention "in flight" at all. The other possible definition might be 14 CFR 1.1 “Flight time” "... Pilot time that commences when an aircraft moves under its own power for the purpose of flight and ends when the aircraft comes to rest after landing ..." but this seems very specific to the logging of time.

In flight does seem to have a pretty common sense definition but I due to some grey areas around taxi/start-up I can think of I am surprised I cannot find an explicit definition.

Answer 1

Other uses of "in flight" make it clear that operating on the surface does not count as "in flight." For instance, from 91.113(g):

Aircraft, while on final approach to land or while landing, have the right-of-way over other aircraft in flight or operating on the surface

So it's the common sense meaning- an aircraft is in flight when it is flying and is not in flight when it is not.