A helicopter that crashed into the roof of the DoubleTree by Hilton hotel in Cairns, Far North Queensland, was stolen and taken on an unauthorized flight, according to the aviation company it belonged to.

Investigations are ongoing to determine who was flying the aircraft, but Nautilus Aviation CEO Aaron Finn confirmed to the ABC that all its pilots had been accounted for.

Up to 400 people were evacuated from the DoubleTree by Hilton on Cairns Esplanade after the crash, which set the top of the building alight shortly before 2 am on Monday, police said.

Two of the helicopter's rotor blades came off and landed on the esplanade and in the hotel pool.

There were no injuries on the ground.

Australian Transport Safety Bureau investigators are on the scene, investigating the fatal chopper crash.

Nautilus Aviation is working closely with Queensland Police, the Australian Transport Safety Bureau, and other authorities as they investigate the unauthorized use of one of their helicopters in the early hours of the morning.

As they continue to fully support the ongoing investigation, they will not be making further comments at this time.

Two hotel guests—a man in his 80s and a woman in her 70s—were taken to Cairns Hospital in stable condition and have since been discharged.

ATSB Chief Commissioner Angus Mitchell described one of the hotel rooms close to the crash as a 'catastrophic sight.

' 'It was devastation, obviously, the blades of the helicopter have gone into the room,' he told the ABC.

He said because of the significant wreckage, it would take some time for investigators to answer questions over the nature of the flight and the sequence of events.

'Now we understand the helicopter was only in the air for a very short period of time coming out of the Cairns airport, down across parts of Cairns itself, and then ultimately into the side of the building,' he said.

'We'll piece that together from not only witness statements and some of the CCTV that have captured it, but equally, what we can actually gather from the crash site itself, any of the recording devices that were on and operable on the helicopter that we can recover now.

' 'And as we know from this particular crash site, we've got debris from across the road, into the pool, and indeed on the helicopter where it landed on the roof.

' He said investigators would also be seeing what was recorded by the air traffic control's primary radar and if the pilot was using the radio.

'We know that a lot of stages of the flight, from our witness statements, the helicopter was quite low,' he said.

'So whether or not that's been picked up by radar, whether the pilot has made any transmissions or not, that's something that we will certainly look into.

' Queensland Police Service Acting Chief Superintendent Shane Holmes said investigations with the ATSB were continuing, and a report would be prepared for the coroner.

'The aircraft was moved from a general aviation hangar early this morning, and it was an unauthorized flight,' he said.

Veronica Knight was outside on the phone to a friend in the US when she saw the helicopter flying past like planes in war movies and tried to film it.

'It meant business.

I got the idea that it was the sort of thing that could crash, it was going so fast,' she said.

It was too dark to see the crash, but she heard it and filmed the flames on the roof from just meters away.

'I was pretty worried because you could see parts of the whole apartments—I was wondering, 'how did it land?'' Hotel guest Alastair Salmon woke up to a 'colossal ear-deafening bang.

' He and roommate Harry Holberton were on the third floor.

Mr.

Holberton said the crash felt like a bomb going off, with flames 'rising up the side of the building.

' 'Suddenly all the alarms start going off and then [people] start evacuating with police yelling 'get out, get out, get out.

'' Mr.

Salmon, who had traveled from London, said he first mistook the helicopter's rotor blade for a lamppost.

'Then we looked up there and you could see this massive hole in the window of the building,' he said.

Mr.

Salmon said he could see 'small fragments of what looked like a helicopter' in the hotel's courtyard.

'It was very loud—I thought it might have been a tower on top of the building exploding, it was that sort of a sound,' he said.

'I'm advised our emergency services put in place all appropriate processes to keep everybody safe,' he said.

'The good news is that the police commissioner advises me they have no reason to believe that there's an ongoing threat to community safety.

' Head of aviation at CQUniversity, Professor Doug Drury, said for a crash to happen in the CBD at that hour was 'very, very unusual.

' A mechanical failure was 'possible,' but landing it on the top of a hotel was the 'last thing' you would do, he said.

'The esplanade itself has lots of areas that can be considered a safer landing zone with the helipad on the point there, as well as parkland,' he said.

'If the aircraft was trying to make it back to land, and the aircraft sounded sick.

.

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it still should not have landed on top of the building.

' Professor Drury said the CBD was a no-fly zone for all low-flying aircraft, except for the authorized rescue chopper.

Asked if it would be possible to fly a helicopter without experience, ATSB chief commissioner Angus Mitchell says it'd be very hard.

'We don't know until the identity of the individual is confirmed, we don't know the experience level, but it is certainly a very difficult thing to do if you haven't got experience of flying a helicopter.

' 'That comes down to whether it was a scheduled flight and it had a flight plan or otherwise, and at this stage it's too early for us to ascertain but certainly, the reporting that we've got at the moment is that that may have been the case.

' We acknowledge Aboriginal and Torres Strait Islander peoples as the First Australians and Traditional Custodians of the lands where we live, learn, and work.

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