Mr Mitchell says the pilot's family are "devastated by what occurred".

"They have asked for their privacy to be respected at this time, but this is a very devastating event for the family and friends of this young man," he says.

This is where we'll leave today's live coverage.

Mr Mitchell says the 23-year-old pilot was drinking with friends throughout the evening before returning to his apartment.

A number of hours later, he left his apartment and headed to the Cairns Airport.

"We do know both from witness accounts and now from the toxicology that the pilot was drinking that night and the blood alcohol was quite significant," he says.

Mr Mitchell says the toxicology report showed "high levels of blood alcohol concentration".

"This certainly was an exceptional set of circumstances, and not normally one that the ATSB investigates," he says.

"While it's tragic that a young man has lost his life, there was significant risk to others in the Cairns area."

Mr Mitchell says the helicopter's altitude did not exceed 500 feet.

Two security cameras recorded very brief portions of the final part of the flight, showing the helicopter pitching up before descending steeply and crashing.

"Tragically, the pilot was unfortunately injured," Mr Mitchell says.

"Fortunately, there were no injuries to hotel guests and staff, nor passersby." 

Mr Mitchell says investigators were able to develop a detailed sequence of events using CCTV, witness accounts, GPS data and data from the helicopter.

They found the helicopter departed Cairns Airport shortly before 1:47am and the helicopter strobe lights were turned off.

"After taking off, the helicopter headed south directly towards the Cairns city centre, flying directly over the pilot's apartment," Mr Mitchell says.

He says it is unlikely any broader safety issues or lessons would be uncovered from the incident beyond what is provided in the report.

"This final report provides assurance to the Cairns community and the aviation industry that after gathering and analysing the available evidence, there are unlikely to be broader safety transport safety issues that require addressing to reduce future risk arising from this tragic accident," he says.

The Australian Transport Safety Bureau (ATSB) has released the final report from its transport safety investigation into a fatal helicopter crash in Cairns.

ATSB Chief Commissioner Angus Mitchell says the pilot conducted "an unauthorised and unnecessary flight at night while affected by alcohol".

"Our report notes that the pilot did not hold the appropriate endorsements to fly at night, did not have any experience flying the R44 at night, and they conducted the flight well below the 1,000 foot minimum height for flight over built up areas."