Pilot error has been identified as the primary cause of a mid-air collision between two US Air Force Boeing F-15C fighters early this year, and a previous lengthy grounding order imposed on the type was not a contributory factor, according to an Accident Investigation Board report into the mishap.

One pilot was killed when the aircraft, assigned to the 33rd Fighter Wing at Eglin AFB, crashed during a 20 February training sortie off the Florida coast. The other ejected and suffered only minor injuries.

"Both pilots failed to clear their flightpaths and failed to anticipate their impending mid-air collision," says the Air Combat Command report. The aircraft - worth a combined $83.3 million - were both destroyed.

"Other possible contributing factors investigated by the board included a loss of flight proficiency during the November 2007-January 2008 stand-down of the F-15A-D fleet," says the 28 August report, along with the lack of a robust risk management programme and training rule violations. "There was insufficient evidence to determine that any one or combination of these factors directly contributed to the mishap," it concludes.

Maintenance and the airworthiness issues were also eliminated as possible factors.

Source: Flight International