A pilot was concerned high workloads would cause distraction and fatigue with potentially dangerous impacts on flying before a fatal army helicopter crash, an inquiry has been told.
Captain Danniel Lyon, Lieutenant Maxwell Nugent, Warrant Officer Class Two Joseph Laycock and Corporal Alexander Naggs were killed when an MRH-90 Taipan plunged into the sea off Queensland's Lindeman Island on July 28, 2023.
Captain Campbell Rogen, a CH-47 Chinook helicopter pilot, told an inquiry into the incident that he and Capt Lyon shared concerns about the demands of secondary appointments on air crew a year before the crash.
Capt Lyon worried the appointments would lead to pilots becoming so distracted they lost flying proficiency and could lead to an accident, Capt Rogen said on Friday.
"I no longer have time to remain proficient or confident within the cockpit because of the imposts of my secondary appointment, and don't feel empowered to prioritise my primary role - a role that ultimately can kill me," Capt Lyon told Capt Rogen in 2022, a statement to the inquiry revealed.
Capt Rogen said the workloads also led to job dissatisfaction among air crew.
"Everyone joins to be an aviator and the sooner that's taken away from you, there's dissatisfaction in that," he said.
"Then you see your own flying skill and progression regress as a result of that.
"That's a hit in pride, job satisfaction and morale."
Capt Rogen said squadron survey results showed the high workloads had caused organisational burnout and fatigue.
Aviation medicine expert Dr Adrian Smith said high workloads and fatigue could result in degraded performance when flying.
"Fatigue might actually start to erode your bandwidth so you've got less capacity, leading to poor cognitive processes," he said.
If air crew were not getting enough sleep, it could result in cumulative fatigue particularly if they consistently worked long hours, Dr Smith said.
A former MRH-90 pilot, referred to by the pseudonym D20, told the inquiry on Wednesday air crew were working 12 to 18-hour days in the months before the crash.
"If you have sort of cumulative fatigue, so rolling over a sleep debt from one night of not full eight hours of sleep, then that means that the next day you need to have more than eight hours' sleep," Dr Smith said.
"To think that a simple rest period is going to wipe out three days of cumulative fatigue is not based in science."
Dr Smith said that night flying could also cause a significant fatigue burden as it took three to four days to adjust to the hours.
"If you're chopping and changing between night flying and day flying, your circadian rhythm never has a chance to reset," he said.
"That means that you're then operating at a significant disadvantage."
D20 also said some air crew were exhausted during the military training exercise Talisman Sabre, days before the crash, due to the switch between shift times.
They said air crew were offered sleeping tablets to help with the change.
Dr Smith said sleeping tablets were a quick fix and had been used in the defence force for decades to help with shift transitions.
"It's not a substitute for natural sleep," he said.
The third tranche of hearings concluded in Brisbane on Friday.
