What happened
On 21 August 2024, a KC-46A (T/N 17-6028) assigned to the 22nd Air Refueling Wing was conducting an aerial refueling mission in Swiss Air Traffic Control Assigned Airspace. The tanker was supporting two F-15E aircraft during a scheduled operation. During the fourth refueling attempt of the sortie, the boom nozzle became stuck in the receiver aircraft's receptacle. Upon the subsequent release, the boom moved upward with high velocity, striking the empennage of the KC-46A. The impact caused the boom to oscillate violently, leading to a critical structural failure of the boom shaft, which resulted in debris falling from the aircraft while in flight. There were no fatalities or injuries reported during the incident, and no civilian property was damaged. However, the estimated damage to the tanker is approximately $14,380,000.
The investigation
The investigation examined the sequence of events surrounding the nozzle binding and the subsequent mechanical failure. The board reviewed the flight control logic of the boom's fly-by-wire system, specifically looking at how the Boom Operator's inputs interacted with the programmed limits during the contact attempt. Investigators also analyzed the flight paths of both the tanker and the receiver aircraft to determine if the separation procedures were executed correctly following the binding event.