Occurrence Investigation Summary

On 19 Jul 2023, a CC150 Polaris and crew were tasked to repatriate personnel and equipment from Exercise Mobility Guardian 23, a multinational Air Mobility exercise led by the United States at Anderson Air Force Base in Guam.

The aircraft, operating under callsign Can Force 3149 (CFC3149), arrived in Guam at approximately 2145 Local Time on 21 Jul 23 and was directed to parking by United States Air Force personnel. After shutting down, the crew carried out post flight checks as well as loading the aircraft with baggage and equipment for the return flight the following day. After completing their duties, the crew departed for the hotel at approximately 2300 Local Time. At approximately 1030 Local Time on 22 Jul 23, the unattended aircraft rolled backwards, followed a curved trajectory, and impacted a French Air and Space Force Airbus A400M parked on an adjacent spot.

The impact resulted in serious damage to both aircraft, but no injuries.

The investigation revealed the aircraft to be serviceable prior to the accident. A lack of installed chocks allowed the aircraft to roll from its position after the parking brake reached its designed holding period of 12 hours. Expectation bias, crew fatigue and checklist design contributed to chocks not being installed as well as the crew not detecting the lack of chocks prior to leaving the aircraft. The investigation recommends changes to checklists, availability of fatigue prediction software for planning, and a review of the Fatigue Assessment Report.