A catastrophic, cascading sequence of events, beginning with the inflight failure of the power takeoff shaft, caused a U-2S surveillance and reconnaissance aircraft to crash June 22 in Southwest Asia, killing the pilot, according to Air Force investigators.

The aircraft was returning to a forward-deployed location from a high-altitude intelligence, surveillance and reconnaissance mission at the time of the accident. It was assigned to the 9th Reconnaissance Wing at Beale Air Force Base, Calif.

The inflight failure of the power takeoff shaft resulted in an instantaneous loss of power to the airframe-mounted accessory drive, according to the Accident Investigation Board report released Oct. 6. That caused the aircraft to lose its hydraulics systems, alternating current and direct current generators, primary cockpit lighting and cockpit multifunctional displays. The failures occurred during a critical phase of flight -- a descending turn below 3,500 feet in preparation for a night landing.

The vibration and noise caused by the inflight failure of the takeoff shaft, followed by the immediate loss of multifunctional displays, led the pilot to conclude the aircraft was experiencing a serious engine malfunction when in actuality the engine was operating, board investigators said.

With the entire mishap sequence lasting only 63 seconds, human factors such as task over-saturation, channelized attention and spatial disorientation substantially contributed to the pilot's loss of situational awareness and the steady descent of the aircraft until it impacted the ground, officials said.

FMI: www.af.mil