А еще можно вот так(кто-то упоминал здесь про подачу флайт-плана в полете):
3.3.1.4 Unless otherwise prescribed by the appropriate
ATS authority, a flight plan for a flight to be provided with air
traffic control service or air traffic advisory service shall be
submitted at least sixty minutes before departure, or, if submitted
during flight, at a time which will ensure its receipt by the
appropriate air traffic services unit at least ten minutes before
the aircraft is estimated to reach:
a) the intended point of entry into a control area or advisory
area; or
b) the point of crossing an airway or advisory route.