James Hamilton has told an inquest into the pilot's death the rescuers faced a choice - to pull David Wood, 62, out from his arms and risk causing serious harm, or wait there with him until he died.

They decided to pull, Mr Hamilton said.

But when Mr Wood came to the surface he curled up on the ice and was "on death's door".

Mr Hamilton was one of three field training officers sent to the fuel cache site on the western ice shelf to rescue Mr Wood.

The pilot had fallen in after getting out of his helicopter to retrieve equipment.

Mr Hamilton said the crevasse was a "big wedge" that got narrower as and bent as it went down. He could not see Mr Wood from the surface.

The court heard Mr Wood was about 14 metres deep in the ice.

Mr Hamilton said when he was lowered into the chasm, he could not reach Mr Wood and had to manoeuvre himself horizontal.

He then could not secure ropes around Mr Wood's waist or upper torso because of how he was wedged in the ice.

He had to secure the pilot's arms instead.

He said Mr Wood's level of consciousness deteriorated during the rescue though the pilot had occasionally responded to him.

"He was definitely repeating himself. 'I'm cold,' 'get me out,'" he said.

When they tried to pull him out he screamed and moaned, he said.

The rescuer was worried about the man's arms being torn off.

Mr Hamilton called for a stop while they talked about their options but there were none.

He agreed their only realistic options were to pull Mr Wood out or stay with him in the crevasse until he died.

The rescue team decided to use more force, he said, and Mr Wood came unstuck.

Mr Wood was still breathing when they pulled him out, he said.

The pilot was flown back to Davis station where he died of hypothermia the following day, on January 12, 2016.

Counsel assisting the coroner, James Stewart, thanked Mr Hamilton for his bravery before finishing his questions.

Under cross-examination, Mr Hamilton told the inquest he had concerns the fuel cache site had not been checked for crevasses.

He also said there was nothing else the other pilot, Paul Sutton, could have done to rescue Mr Wood except return to Davis for help.

After a coroner's ruling earlier on Thursday, a key witness to the circumstances in which Mr Wood died will be free to give evidence about his investigations into the death.

William De Bruyn was both station leader and deputy coroner at the time of Mr Wood's death, two roles he was appointed to by the government before the summer in Antarctica.

In the days after the pilot died, Mr De Bruyn collected evidence and spoke to witnesses, and then prepared reports.

He believed he was acting under the powers given to him as a deputy coroner.

The situation caused headaches at the Canberra hearing this week, which heard Mr De Bruyn would be prevented by law from giving evidence in court about matters he had learned acting in the role.

But on Thursday, Chief Coroner Lorraine Walker ruled that based on the evidence before her, and though Mr De Bruyn had been appointed to the role of deputy coroner, and though he and others, including herself, had been under that apprehension, Mr De Bruyn was not acting as a deputy coroner when he did those investigations.

She said he was performing an investigative role under the direction of the ACT Coroner's Court, which had been notified about one hour after Mr Wood's life was declared extinct.

Mr De Bruyn will return to give evidence at a later date.

The inquest continues on Friday.