On 20 December 2004, at 2340Z/1540 local time, the Mishap Aircraft (MA), F/A-22, Serial Number 00-
4014, crashed on initial takeoff from Nellis AFB. The Mishap Pilot (MP), assigned to the 422nd Test
and Evaluation Squadron, Nellis AFB, ejected safely and sustained only minor injuries. There were no
other casualties. The MA impacted the Nellis AFB airfield and was destroyed. The only other damage
was also to government property including an arresting cable, a runway sign, a runway light, and the
Immediately upon leaving the ground, the MA began a series of un-commanded and progressively
more violent yaw, roll, and pitch transients. Unable to control the aircraft, the MP ejected seconds
before the MA impacted the ground.
The Accident Investigation Board President determined the cause of the mishap, supported by clear
and convincing evidence, was an inoperative Flight Control System, resulting from a power
interruption, which made the MA uncontrollable. The MP was , unaware of this condition because he
did not perform an Initiate Built in Test (IBIT), the only means of detecting the problem. Failure to
perform the IBIT was the result of ambiguous Technical Orders and a mistaken belief in continuous
RSA power availability.
During the mishap sequence, the MP started engines, performed an IBIT, and had a fully functioning
Flight Control System. Subsequently, the MP shut down engines to allow maintenance personnel to
service the Stored Energy System. During engine shut down, the MA’s Auxiliary Power System (APU)
was running. The MP believed the APU provided continuous power to the Flight Control System, and
therefore another IBIT after engine restart was unnecessary. This belief was based on academic
training, technical data system description, and was shared by most F/A-22 personnel interviewed
during the investigation.
In fact, the MA’s Flight Control System did experience a brief power interruption during the engine
shut down sequence. The interruption produced an unforeseen catastrophic Flight Control System
failure that rendered the MA un-flyable.
Under 10 U.S.C. 2254(d), any opinion of the accident investigators as to the cause of, or the factors
contributing to, the accident set forth in the accident investigation report may not be considered as
evidence in any civil or criminal proceeding arising from an aircraft accident, nor may such information
be considered an admission of liability by the United States or by any person referred to in these
conclusions or statements.