WordNet (r) 3.0 (2006):

flight path
    n 1: the path of a rocket or projectile or aircraft through the
         air
    2: a designated route followed by airplanes in flying from one
       airport to another [syn: air lane, flight path, airway,
       skyway]

Moby Thesaurus II by Grady Ward, 1.0:

28 Moby Thesaurus words for "flight path":
   air lane, amplitude, beat, camber, circuit, course, itinerary,
   line, orbit, path, primrose path, road, round, route, run,
   sea lane, shortcut, skin effect, skin friction, slip, stagger,
   tour, track, trade route, traject, trajectory, trajet, walk