 The aircraft then descended in a nose-down attitude and disappeared from sight behind trees near the airport.One witness told investigators that they saw a puff of smoke emanate from the aircraft prior to or subsequent to the airplane rolling to the left.Others reported loud engine noises described as a squeal, whine, or an overspeeding or accelerating engine during the last moments of the flight, although they said that these noises seemed to have stopped, or at least faded before the aircraft impacted with flat ground two miles short of the runway.