Accident Summary
On 21 August 2024, at approximately 0927 hours local time, a KC-46A Pegasus (tail number 17-6028) assigned to the 22nd Air Refueling Wing, McConnell AFB, Kansas, was conducting an aerial refueling mission in the Swiss Air Traffic Control Assigned Airspace with an F-15E Strike Eagle (tail number 90-0246) and its wingman, both from the 366th Fighter Wing, Mountain Home AFB, Idaho. During the fourth refueling attempt of the sortie, the KC-46A experienced nozzle binding of the boom in the F-15E's receptacle. Upon release, the boom rapidly flew upward, struck the empennage of the KC-46A, and violently oscillated left and right. The impact and subsequent oscillations resulted in critical failure of the boom shaft structure, causing portions of the boom to fall from the aircraft in flight. There were no fatalities, injuries, or damage to civilian property. The estimated damages to the KC-46A are $14,381,303.
Investigation Findings
The Accident Investigation Board President determined, by a preponderance of the evidence, that the cause of the mishap was the Mishap Boom Operator's control inputs to the air refueling flight control system, which led to an excessive fly-up rate of the boom, causing it to strike the aircraft empennage and result in critical failure of the boom shaft structure. Additionally, the Board found that several factors substantially contributed to the mishap: excessive closure rate and instability of the F-15E; the Mishap Boom Operator's attempted contact outside the standard air refueling envelope for the F-15E; Mishap Pilot 3's failure to recognize and initiate immediate breakaway procedures, delaying positive separation from the KC-46A; and the Mishap Boom Operator's lack of knowledge on boom flight control logic and its effects on the boom flight control surfaces, preventing recognition of the influence of Flight Control Stick inputs and programmed boom limit functions during operations, especially during nozzle binding situations.
Damage Assessment
The boom structure sustained critical failure, with portions separating from the aircraft. The KC-46A empennage was struck by the boom, but detailed damage to the aircraft beyond the boom is not specified in the report. The total repair cost estimate is $14,381,303.