Military investigators have revealed the sequence of events that led the Royal Canadian Air Force plane normally used by the prime minister to run into a tow tractor and hangar wall and suffer severe damage.
The crash at Canadian Forces Base Trenton in Ontario occurred last October and left the Airbus CC-150 Polaris known as "01" with structural damage to the nose and right engine that is still being repaired.
The timeline released Thursday — which reads like a comedy of errors — starts with contracted groundcrew with L3Harris towing the aircraft to a hangar "not routinely used" by the plane and too small for the tow tractor.
The maintenance crew set the plane's parking brake and put chocks on its wheels to keep it from rolling while they went to hook up a smaller tractor that would fit in the hangar, according to the report.
"During the tow tractor change, the aircraft started moving forward and jumped over the chocks," the report reads.
"Attempts to stop the aircraft by the tow crew were unsuccessful. The right engine struck the D-12 tow tractor parked inside the hangar before the nose contacted the hangar far wall structure, finally stopping the aircraft."
In addition to the damage to the plane, which the Department of National Defence has estimated at around $11 million, the investigators said one person received a minor injury.
Investigators could not say why the parking brake disengaged. But they did cite a lack of brake training as a cause for concern and said they found the chocks used to secure the plane did not meet standards and were not installed on all the wheels.
"The investigation recommends the use of approved chocks on all wheels and improved training for towing operations."
Officials previously said repairs on the aircraft would be finished by August, but that has been pushed back to January due to travel restrictions from COVID-19.
Defence Department spokesman Daniel Le Bouthillier said the government has asked L3Harris to repay the cost of the repairs "as the aircraft was in their care and custody when the accident occurred."