An army helicopter involved in a fatal crash during a training exercise was difficult to fly unless you had a lot of experience with the machine, an inquiry has been told.
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 during a military training exercise.
Many aircraft personnel had not participated in enough flying hours to be completely familiar with the MRH-90 Taipan helicopter, an inquiry into the crash was told on Tuesday.
Major Michael Gallatly, a pilot and colleague of the men killed, said the aircraft was high maintenance and not serviceable.
"It is a very complex aircraft and if you could fly it regularly, and you'd be able to learn to use those systems, it would have become much easier," he told the hearing in Brisbane.
"But when you do it infrequently, the content is a little bit overwhelming, because you actually don't know what button you need to press, or where the switch is ... the checklist is huge."
Maj Gallatly said the MRH-90 was "underperforming" with a lack of availability of the aircraft because of its maintenance demands.
But he said it was a safe helicopter to fly.
On any given day there would be six serviceable and functioning aircraft out of 12, he said, meaning junior air crew often did not have enough flying hours with the helicopter.
"Flying for the junior air crew wasn't prioritised because there was no ability to prioritise it, because it was consumed with maintaining the aircraft and completing the training," the major said.
This meant senior air crew were overworked because they were required to fly in the majority of training exercises and missions.
Maj Gallatly recalled an incident flying an MRH-90 with Capt Lyon where the aircraft lost speed and nose dived.
He was forced to disconnect the autopilot to lift the helicopter back to a safe altitude.
Maj Gallatly said Capt Lyon told him the MRH-90 on autopilot would prioritise air speed over altitude, similar to a passenger plane.
The ADF earlier applied for the inquiry to wait until a Defence Flight Safety Bureau report was handed down and to remove two witnesses from giving testimony.
ADF's counsel Andrew Berger KC suggested continuing without the report would raise questions over the validity of the inquiry's findings.
Justice Margaret McMurdo said pausing the inquiry for the report - due to be released in December after multiple delays - would be difficult for families of the victims.
"I accept that it is highly desirable for the inquiry to obtain the final relevant DFSB report as early as possible," she said.
"But where that report is delayed, I consider it would be remiss of this inquiry not to continue the investigations it's lawfully charged to conduct in a timely way."
Ms McMurdo rejected the application and asked for the report be handed down as soon as possible.
The inquiry continues on Wednesday.
