The force of the impact on an aircraft depends on the weight of the animal and the speed difference and direction at the point of impact. The energy of the impact increases with the square of the speed difference. High-speed impacts, as with jet aircraft, can cause considerable damage and even catastrophic failure to the vehicle. The energy of a bird moving at a relative velocity of approximately equals the energy of a weight dropped from a height of . However, according to the FAA only 15% of strikes (ICAO 11%) actually result in damage to the aircraft.