The workplace health and safety regulator is recommending the Australian Defence Force face prosecution over an army helicopter crash that killed four soldiers.

The grieving families of the victims told a parliamentary inquiry of the 'incredibly hurtful' treatment they received from the military their loved ones died serving. 

Captain Danniel Lyon, Lieutenant Maxwell Nugent, Warrant Officer Class 2 Joseph Laycock and Corporal Alexander Naggs were killed when their MRH-90 Taipan chopper crashed into waters off Queensland's Whitsunday Islands during Exercise Talisman Sabre on July 28, 2023.

The regulator, Comcare, has referred two briefs of evidence to the Commonwealth Director of Public Prosecutions relating to fatigue management and the TopOwl helmet-mounted display worn by the pilots, Chief Executive Colin Radford told the inquiry on Friday. 

The regulator was informed by Commonwealth prosecutors in July 2025 they would not prosecute the defence force, because they did not consider there were reasonable prospects of obtaining a conviction.

'Comcare considered there was evidence to support a view that defence may have committed one or more offences under the Work Health and Safety Act,' Mr Radford said.

'I would like to stress ... that Comcare's investigation into this incident remains open.'

He said it was the regulator's view that inquiries conducted by the Inspector-General of the Australian Defence Force and the Queensland coroner might extend the limitation period by a further 12 months.

Under questioning by senators, Mr Radford said the regulator believed prosecution should proceed.

Giving evidence at the hearing at Parliament House, family members and partners of the dead soldiers said they were not given adequate information or support and described the 'incredibly hurtful' way defence treated them.

Caitland Lyon, the widow of Captain Lyon, who was the pilot of the helicopter, demanded accountability and answers.

'He trusted that organisation that he served would keep him safe,' she tearfully told the inquiry.

'That trust was catastrophically betrayed.'

Daniel Nugent, the father of Lieutenant Nugent, said he just wanted ADF officers to provide straightforward answers to questions surrounding his son's death.

'The word salad and the stretching of words ... that damages their reputation because they just cannot be honest,' he said.

An emotional Sarah Loft, the partner of Corporal Naggs, said there was a lack of information from defence.

'I've had to piece together information that should have been clear, consistent and proactively provided,' she said. 

'I ask this committee to acknowledge the harm that has occurred, to commit to meaningful reform, and to ensure that no family is left to navigate what we have endured.'

The Defence Flight Safety Bureau's investigation found the primary cause of the fatal crash was 'spatial disorientation', which occurs when a pilot misperceives the position of their aircraft in relation to the surrounding environment.

The report concluded that the pilots were likely experiencing a level of fatigue shown to 'impede optimal performance' and increase susceptibility to spatial disorientation.

But former Taipan test pilot, retired Major Ian Wilson, told the inquiry the Defence Flight Safety Bureau's investigation 'could not be trusted' and had been 'corrupted'. 

'There was an obvious and well-known conflict of interest within the investigation team,' he said.

Major Wilson said concerns about the software upgrade for the TopOwl were ignored despite testing deeming it an unacceptable risk.

A separate inquiry heard safety concerns were raised about a software upgrade for the TopOwl helmets worn by the pilots on the night of the crash. 

The crew, from the Sydney-based 6th Aviation Regiment, were flying in a helicopter given the call-sign Bushman 83, which was the third in a formation of four aircraft as part of a training exercise.

The parliamentary inquiry is examining the crash, with specific reference to the decision not to prosecute any matters arising from the incident.

A report is due in September.