Fatigue was a major concern for air crew in the days and months before a fatal army helicopter crash killed four soldiers, an inquiry has heard.
Captain Danniel Lyon, Lieutenant Maxwell Nugent, Warrant Officer Class Two Joseph Laycock and Corporal Alexander Naggs were killed when their MRH-90 Taipan plunged into the sea off Lindeman Island in Queensland on July 28, 2023.
A former MRH-90 pilot, referred to by the pseudonym D20, told an inquiry into the crash they were working 12 to 18 hours a day on weekdays and four to six hours on weekends in the months before the incident.
Their colleague Capt Lyon - who had the nickname "Diesel" - was also doing long hours but D20 tried to protect him.
"I know Diesel was doing weekends ... I tried really hard to not let Diesel get loaded up because I was single," D20 told the hearing in Brisbane on Wednesday.
"Dan was married, and he had two young kids and I thought it was really important that he didn't have to go through what I was going through."
Standard hours were 7.30am to 4pm, however, for the aviation regiment it varied to accommodate for night flying, D20 explained.
"There is an expectation to complete directed tasking ... in order to complete those tasks it came at the cost of increased hours, or not being able to complete another task," they said.
It was common to work six to seven days a week, D20 said.
There were times D20 elected not to fly due to their fatigue levels and encouraged troop members to do the same.
"(We) really tried to ensure that our members had as much time to recover as they could," they said.
They recalled the culture becoming "toxic" when defence headquarters did not recognise the impact of fatigue or the need for time off.
"It was becoming quite toxic and it wasn't a good environment," D20 said.
"I think the perception of what we were doing, when we were trying to manage fatigue and ensure people had time at home with their families, that perhaps was viewed as 'Oh, well, they're not physically here, they're just off skiving again'."
In the days before the crash at military training event Talisman Sabre, D20 revealed air crew were offered sleeping tablets after the ground trial to help them switch from day to night shifts.
"The aviation doctor on the trip with us then was able to get a hold of the medication and basically prescribe it to members," they said.
D20 recalled they and other pilots were experiencing fatigue during the training week.
They made the decision to pair Capt Lyon, Lt Nugent, WO2 Laycock and Corp Naggs on the fatal flight due to their different skill sets.
D20 raised concerns about Capt Lyon and Lt Nugent being paired together based on their piloting experience levels, however, the decision was endorsed by fellow senior officers.
The night before the crash, D20 opened up to their colleagues about their struggle with the career pressures and lack of progression.
"I've worked myself into the ground, and it still isn't enough to be seen as worthy, to be progressed as a pilot. I need to get out of here today," D20's statement, read by counsel assisting Alexandra Rose, said.
D20 left Talisman Sabre as a result of their emotional state on July 28 where Capt Lyon took over as troop commander for the training mission.
They were called later that day and notified of the fatal crash.
The inquiry continues on Thursday.
