Human error has been officially blamed for a dramatic incident in which a RAAF Super Hornet pilot and a weapons officer ejected from their aircraft during an aborted take off.
The emergency in December 2020 saw the aircraft veer off the main runway at RAAF Base Amberley, outside Brisbane, before rolling to a stop adjacent to the cross runway.
Both RAAF members escaped with minor injuries and the jet was able to be repaired and returned to service at a cost of about $1.5 million.
A partially redacted aviation safety investigation report from the Defence Flight Safety Bureau (DFSB), obtained by outgoing independent Senator Rex Patrick, has for the first time publicly revealed the contributing factors.
"During the take-off roll, the aircraft departed the right side of the sealed runway surface, culminating in both aircrew ejecting," the report states.
"Base emergency services were notified immediately, and the crew was recovered and medically assisted.
"Both aircrew suffered minor injuries from the ejection, and the aircraft sustained moderate damage."
The DFSB's investigators found that "substandard adherence to checklist actions prior to the aircraft lining up resulted in a 'master caution' and 'check trim' message on the left digital display indicator as the throttles were advanced into afterburner for takeoff".
"During the takeoff roll, the check trim [indicator] caution distracted the pilot from prioritising focus on directional control, resulting in the aircraft's deviation in heading to go unnoticed/uncorrected for several seconds," the investigators found.
They added that "the crosswind conditions on the day, aircraft line-up position, and asymmetric stores loading exacerbated the tendency for the aircraft to deviate right from runway heading".
"Upon noticing the heading deviation, it is likely the pilot suffered an acute stress response followed by a short duration of impaired cognitive performance," the report states.
"During this period, a series of action errors were made in an attempt to correct and maintain directional control of the aircraft."
The report found as the Super Hornet reached its maximum ground speed the landing gear left the runway, hitting a runway edge light and causing the nose wheel steering to fail.
Without that, the aircraft was sent spiralling further off the sealed runway, where it hit a concrete mound and left the ground.
That led to the rear-seat weapons system officer "initiating the command ejection of both crew from the aircraft".
Investigators found the ejection likely cut the aircraft's throttles, and the jet continued to roll at idle thrust until it came to rest about 930 metres from the point of departure from the runway, and 200 metres right of the runway centreline.
Operations of the RAAF's fleet of 24 F/A-18F Super Hornets and 11 EA-18G Growlers were suspended until December 18, 2020.
In a formal response to questions from Senator Patrick during senate estimates, Defence revealed the cost of repairing the jet was $1.51 million.
The DFSB released the aircraft from investigatory quarantine for maintenance and remediation on February 2, 2021, and it was reportedly returned to service in mid-2021.
