A "hero" helicopter pilot is facing possible jail-time over the dramatic rescue of an injured hunter who says he owes the pilot his life.

Hunter Scott Lee was left dangling on the edge of a 50-metre drop after falling in remote bush north of Kaikoura on April 5, 2014.

He suffered a broken femur, and had to be tethered to a tree with his girlfriend's clothing to prevent him from plunging further down the bluff to his death.

SUPPLIED Stricken hunter Scott Lee is helped by Search and Rescue from where he was tied to a tree above a 50-metre drop by his girlfriend's clothing.

Local pilot Dave Armstrong stepped up to complete the rescue after another helicopter had already turned back.

But now he faces charges because his licence was at the time suspended, due to a medical scare from a diagnosis which had already been called into question.

The prosecution is thought to be the first of its kind in New Zealand for a pilot performing a search and rescue mission.

SCOTT HAMMOND Dave Armstrong manages Kaikoura Helicopters.

The situation has outraged some in the flying community, as well as the hunter Armstrong saved, with the Christchurch man saying he was "absolutely devastated" for the pilot.

Lee has written to the Civil Aviation Authority (CAA) pleading for them to drop the three charges Armstrong is facing next weekin Kaikoura District Court.

In the letter he explains how he had gone after his girlfriend, Lisa McKenzie, who had tumbled down a shingle bank, before tripping and badly breaking his leg on the tree that broke his 15-metre fall.

TONY BENNY/ FAIRFAX NZ The remote Puhi Puhi Valley, Kaikoura, where the couple got into strife.

The first rescue chopper had been forced to turn back due to low fuel.

Armstrong then attempted the rescue, and it is understood he sat alongside his co-pilot as a supervisor because he was suspended from flying.

But his junior struggled to make the manouevre in their Robinson R44 light four-seater machine.

Kaikoura Search and Rescue (SAR) alternate controller Mike Morrissey said it was cloudy, the couple were in dense bush on a steep slope, and the view was that Lee could not be left overnight in such conditions.

Armstrong took the controls instead and dropped in Morrissey, a doctor, and the rest of the SAR team .

"Dave knew exactly where these guys were," Morrissey said.

"He's been flying to do rain gauges there every month for years.

"At that time Dave had the opportunity to do it. He was the best person for it so we used him."

Lee said he and his girlfriend had lost hope after hearing the first chopper turn back.

He had even accepted he might die alone by the time he heard the approach of Armstrong's chopper.

It took the SAR crew about six hours to stretcher Lee out of the bush, Morrissey said.

A source close to the case said Armstrong's flight-logs were later seized by police on behalf of the CAA.

The source said the day Armstrong flew, there was doubt about his medical issue and he had been challenging the opinion while trying to get the grounding order lifted.

Lee and McKenzie both wrote to the CAA in support of Armstrong when they heard of the prosecution.

"We truly believe that we owe our lives to Dave and the team that helped us, and there is no way we will ever be able to express our gratitude to them."

Lee wrote: "Clearly it was a life or death situation and we are grateful that Dave made that decision as I would not be here without him."

He said the pilot did not deserve such scrutiny.

"He's done a heroic act in my eyes. If anything, he deserves a medal for what he's done," Lee said. "He's a hero."

Wanaka pilot and Armstrong's friend, John Levy, said the cost of the prosecution and being grounded had affected the family's livelihood.

A spokesman for the CAA said it was not in a position to comment on the case while the matter was before the courts.

Armstrong and his lawyer also declined to comment.

THE CHARGES

The charges relate to alleged breaches of the Civil Aviation Act for performing search and rescue flights without a current medical licence.

The Act, which is currently under review, says pilots can breach the law in life or death emergencies, but not if they are not lawfully entitled to fly.

That includes for medical reasons, or if their craft is not airworthy.

The maximum penalty is 12 months' jail or a $10,000 fine per offence.