Qantas boss Alan Joyce has fended off criticism of the airline's profit and concerns over high ticket prices, saying he expects international fares to fall.

Mr Joyce on Monday faced a tough parliamentary committee hearing examining the cost-of-living crisis.

Qantas on Thursday posted a record pre-tax profit of $2.47 billion for the past financial year, after recording a loss of almost $2 billion the year before.

"There's lots of criticism of corporate profits at the moment, due in large part to the cost-of-living pressures happening in parallel and we understand that," Mr Joyce said.

Coalition senators asked the airline chief whether Qantas had colluded with the government to block competition from Qatar Airways, which was rejected in a bid for extra flights.

Despite both airlines being members of the Oneworld alliance, Qantas opposed the Qatar plan.

Mr Joyce said the airline made representations to the government, with a letter sent in October.

But he said Australia had one of the most open markets in the world.

Greater capacity being brought on by Singapore Airlines and China Southern would "bring down airfares quite considerably" in 2024, he added.

The airline is facing a possible class action over flights cancelled during COVID-19, but the committee was told Qantas had refunded $3 billion worth of travel credits.

However, there were $370 million worth of unclaimed credits, set to expire at the end of 2023.

The committee heard media campaigns, advertising and text messages were being used to encourage people to claim the credits and get the balance to zero by the end of December.

Labor senator Tony Sheldon told Mr Joyce during the inquiry his company was the most complained about in Australia.

"This is one of the most discredited companies ... on its record of complaints and you're saying you deserve every dollar you've received," Senator Sheldon said.

Assistant Treasurer Stephen Jones earlier said the government wanted to ensure it was driving down the cost of airline tickets in Australia, but not at the expense of the industry.

"Having a national airline that occasionally post a profit is not a bad-news story, (it) is actually a good news story," Mr Jones told reporters.

Putting forward solutions to lower ticket prices, Mr Joyce called for a sustainable aviation fuel industry which would reduce emissions and be a huge opportunity for jobs and economic growth.

"It would reduce the impact of big swings in oil prices and would help bridge a significant gap in Australia's energy independence," he said.

Sustainable aviation fuel was the "most significant tool airlines have to decarbonise".

The outgoing airline boss said increased airport pricing would prove a "major cost pressure" for the Qantas Group.

"The regulatory regime that governs the relationship between airports and airlines isn't working," he told the hearing.

As the government prepares to release its aviation white paper in 2024, Mr Joyce said policies were needed to help with efficient resolution of commercial disputes between airlines and airports.

Liberal frontbencher Anne Ruston said passengers could not take any comfort from Mr Joyce's appearance.

"There are some very big questions not just to be answered by Qantas but to be answered by the government," she told the ABC.

© AAP 2023

Rescue crews are working to recover the bodies of three US marines killed in a military plane crash on a remote Northern Territory island.

A US military Boeing MV-22B Osprey tilt-rotor aircraft carrying 23 marines crashed on Melville Island, 80km north of Darwin on Sunday morning.

Three Americans have been confirmed dead and five were transferred to Royal Darwin Hospital on Sunday night, one in critical condition.

Six have serious injuries and 13 are "walking wounded" with broken bones but were able to assist paramedics with transfers.

Investigations are underway as to what caused the crash, though the operation on the island has turned from a rescue mission to a recovery mission, NT Commissioner Michael Murphy said on Monday morning.

"(The deceased) are part of the recovery operation at the moment," Mr Murphy told ABC radio.

A Code Brown alert declared at Darwin hospital on Sunday, the country's highest level of alert, was lifted on Monday morning.

The Department of Defence said the incident occurred during Exercise Predator's Run 2023 and no Australian Defence Force members were involved.

Defence Minister Richard Marles told ABC radio local services were on the scene of the crash "almost immediately".

"I think that's played a really important part in making sure we've had as many people survive as possible from this crash," he said on Monday.

"Twenty-three people were on board and 20 people have survived the crash, which is remarkable."

He said questions over the safety of the Osprey aircraft were a matter for the US Defence Force but Australia would rely on US certification and safety processes when operating with US forces when Ospreys were deployed.

The Marine Osprey aircraft has a tumultuous history, with a number of mechanical and operational issues since its introduction in the 1980s.

Since 2012, 19 people have died in six crashes involving the Osprey.

Opposition Leader Peter Dutton said the government was doing everything it could.

"(The families) will be feeling this loss very acutely. So we pass out our thoughts and our prayers on to all of those who are affected by this tragedy," he said on Monday morning.

ANU security expert John Blaxland told SkyNews the crash would have long-term emotional and physical repercussions.

Those who are obviously maybe less seriously injured, but still pretty severely traumatised by the experience, they can slip incredibly quickly," he said.

"The very violent movement that can have long-term repercussions as well."

US Defence Secretary Lloyd Austin also issued a statement on the dead and injured marines.

"These marines served our country with courage and pride and my thoughts and prayers are with their families today and with the other troops who were injured in the crash and with the entire US military community family," he said.

The US embassy on Monday issued a statement thanking members of the rescue operation.

"Australians and Americans have been the closest of friends for over 100 years and we're thankful for their continued friendship and support at this time," it said.

About 150 US Marines are stationed in Darwin and taking part in military drills alongside personnel from Australia, the Philippines, East Timor and Indonesia.

© AAP 2023

A recovery mission continues for three US marines killed in a chopper crash off the Northern Territory, as inquiries hope to determine why the aircraft ditched.

Of the 23 marines on the military Boeing MV-22B Osprey tilt-rotor aircraft, three were killed, one is in ICU, seven are in general hospital wards and 12 have been discharged.

"We're incredibly lucky and incredibly thankful, for a chopper that crashes and then catches fire, to have 20 marines that are surviving, I think that's an incredible outcome," NT Police Commissioner Michael Murphy said on Monday.

The aircraft plunged to the ground on remote Melville Island, 80km north of Darwin on Sunday morning, sparking a significant rescue operation.

Twenty marines were transferred to Royal Darwin Hospital overnight, while rescue crews continued to work to recover the bodies from the crash site, which could take up to 10 days.

"This recovery and investigation will be prolonged, enduring and complex," Mr Murphy said.

"We are planning to be at the crash site for at least 10 days."

He said "absolutely everything" had been dedicated to the incident, to work out "the truth of what happened".

NT Chief Minister Natasha Fyles said the territory was prepared for an incident of this scale and assured the families of the injured they were receiving good care.

"We do plan for these types of events, we hope that they never happen, but tragically when they do, we can respond," Ms Fyles said.

The chief minister said the loss of the marines would be felt widely.

"These people weren't simply here for a few weeks on an exercise," Ms Fyles said.

"They're a rotational force that comes through the Top End every year and they integrate themselves into our community.

"They attend sporting events, they attend schools and they provide support, so they're certainly part of our community."

The Department of Defence said the incident occurred during Exercise Predator's Run 2023 and no Australian members were involved.

The Marine Osprey aircraft has a tumultuous history, with a number of mechanical and operational issues since its introduction in the 1980s.

Since 2012, 19 people have died in six crashes involving the Osprey.

Australia's Defence Force does not use the Osprey aircraft, an ADF spokesperson confirmed.

About 150 US marines are stationed in Darwin for the military drills alongside personnel from Australia, the Philippines, East Timor and Indonesia.

The exercises were paused after the crash but have resumed.

US President Joe Biden commented on the situation.

"Jill and I send our deepest condolences to the families of the marines who lost their lives in this deadly crash," he posted to X, the social media platform formerly known as Twitter.

"We are praying for those who also suffered injuries."

Prime Minister Anthony Albanese sent his condolences, adding the quick emergency response showed the "best of the Australian character".

"We have no closer allies than the US. And this incident is, indeed, tragic," he said in Perth on Monday.

The US embassy on Monday issued a statement thanking members of the rescue operation.

"Australians and Americans have been the closest of friends for over 100 years and we're thankful for their continued friendship and support at this time."

Relatives of those killed are being informed and a statement on the victims is expected on Tuesday.

Open Arms 1800 011 046

© AAP 2023

Victorian medicinal cannabis users will be put through a closed-track trial to see when it's safe for them to get behind the wheel.

The 18-month trial will look at the level of impairment medicinal cannabis can cause.

It will not take place on public roads to ensure there's no safety risk to participants or members of the public, a government spokeswoman said.

"Safety on our roads is our number one priority," the statement read.

"This trial will give us more data about when medicinal cannabis patients can safely drive on the road."

Current roadside drug testing can only identify if THC is present in a person's system, not whether it's come from medicinal or recreational cannabis.

The trial will not change the fact it's illegal to drive on Victorian roads while under the influence of THC.

Legalise Cannabis Victoria urged the government the complete the whole process no later than by the end of 2024.

Medicinal cannabis users should also be treated like any other person on prescription medication, Legalise Cannabis MP David Ettershank said.

"There have been dozens of studies that have been replicated many times to show that medicinal cannabis patients can drive safely," he said.

"There is nothing about this driving trial that is uniquely Victorian or Australian."

© AAP 2023