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Posted 12/16/2010   Updated 12/16/2010 Email story   Print story


Release Number: 100024

12/16/2010 - HURLBURT FIELD, Fla. -- 
Air Force Special Operations Command officials released the results of their investigation into the April 9, 2010 CV-22 aircraft accident near Qalat, Afghanistan that killed four and injured 16 of the 20 onboard. The pilot, flight engineer, an Army Ranger, and a civilian contract employee were killed in the crash.

Under the authority delegated to him by the AFSOC commander, the AFSOC vice-commander convened an Accident Investigation Board (AIB) to investigate the matter and designated Brig. Gen. Donald Harvel, the Air National Guard assistant to the commander, AFSOC, Hurlburt Field, Fla. as the board president.

Concluding the investigation, the board president could not determine the cause of the mishap by the standard of "clear and convincing evidence," in part because the flight incident recorder, the Vibration Structural Life and Engine Diagnostics control unit, and the right engine were destroyed and therefore not available for analysis. After an exhaustive investigation of the available evidence, the board president ruled out multiple possible causes. Items ruled out included loss due to enemy action, environmental brownout conditions and vortex ring state. In addition, a design problem that led to the replacement of the Central De-ice Distributor (CDD) support bracket found in all Marine Corps and Air Force Ospreys, was not a factor.

The board president determined 10 factors substantially contributed to the mishap. These included inadequate weather planning, a poorly executed low visibility approach, a tailwind, a challenging visual environment, the mishap crew's task saturation, the mishap copilot's distraction, the mishap copilot's negative transfer of a behavior learned in a previous aircraft, the mishap crew's pressing to accomplish their first combat mission of the deployment, an unanticipated high rate of descent and engine power loss. Substantially contributing factors play an important role in the mishap sequence of events and are supported by the greater weight of credible evidence.

The convening authority approved the board president's report, with comments. While legally sufficient, he assessed the evidence in the AIB report did not support a determination of engine power loss as one of the 10 substantially contributing factors. The convening authority made this decision based upon the evidence in the AIB report and additional analysis of the evidence in the report. The convening authority concluded the preponderance of credible evidence did not indicate engine power loss as a substantially contributing factor of the mishap.

After a review of the original AIB report, the convening authority's statement of opinion and additional material obtained after the completion of the AIB report, the Chief of Staff of the Air Force reopened the investigation and directed the AIB Board President to analyze the additional information.

The Board President conducted a follow-on investigation to analyze two Naval Air Systems Command (NAVAIR) reports and the convening authority's analysis of video data. After consideration of the new material the only fact the AIB president changed from his original report was the ground speed of the aircraft at impact from what was believed to be 75 knots to 80 knots at the time of impact. The remainder of the findings was unchanged.

The primary purpose of the board was to provide a publicly releasable report of the facts and circumstances surrounding the accident. An executive summary of the report is available at The entire report will be available at or by contacting the AFSOC Public Affairs Office at (850) 884-5515.



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