Pilot Phil O'Driscoll, 45, was taken to Canberra Hospital in a stable condition with head and spinal injuries after his UH-1H helicopter came down near Cabramurra on Tuesday afternoon.

He was winched to safety from the remote crash site by the Toll rescue helicopter, ACT Ambulance general manager Matt Smith said.

"When an aircraft falls out of the sky from a height the damage that can be done, and the injuries to the patient, can be quite significant so he was quite lucky," he told reporters in Canberra on Wednesday.

The pilot, who has more than 20 years' flying experience, was working on the Snowy Hydro 2.0 project at the time. At the weekend he helped fight a blaze that's blackened close to 4000 hectares southwest of Sydney.

Rugged and inaccessible bushland has made it difficult for the four-person investigation team from the Australian Transport Safety Bureau to reach the crash site.

Footage of the site, provided by the Australian Maritime Safety Authority, shows the badly damaged helicopter upside down in trees near a creek while rescue helicopters circle the site.

The ATSB team will be flown to a nearby access point as Mr O'Driscoll's helicopter went down five kilometres from the nearest road, a spokesman told AAP on Wednesday.

"ATSB investigators will be examining the wreckage, amongst other activities for the next two days," the spokesman said.

"Investigators will also be interviewing witnesses."

Mr O'Driscoll narrowly escaped death in 2005 after his helicopter smashed into a cliff in the Canadian wilderness as he tried to avoid hitting people, News Corp Australia reported in 2010.

The helicopter was donated to the pilot by a Northern Territory family eight years ago to help him get back on his feet.

AAP understands he is still recovering in Canberra Hospital.

The ATSB will publish a preliminary report in May and a final report in 2019.

Australian Associated Press