Air ambulance nurse Maureen Roberts will never forget the terrifying moment her pilot became her patient mid-flight.

The now 70-year-old was flying from the New South Wales town of Coffs Harbour in 1994 when the pilot started to feel unwell.

"I said would you like a drink of water and by the time I came back he was slumped over the controls," she recalled.

"My heart skipped a few beats. A million things are going through your mind and you're trying to find a pulse."

With the assistance of another person on board, Ms Roberts cleared the pilot's airways and gave him oxygen while the plane continued flying on auto pilot.

"After a few minutes he did wake and he asked me to stay in the cockpit and focus on all his numbers et cetera because everything was a bit hazy," she said.

"Things happened so quickly. You don't want to die so I guess you'll do anything!"

Maureen Roberts was labelled a hero in a newspaper article in 1994, after she revived a pilot who fell unconscious during a flight. ( Supplied )

Emotional end to long and exciting career

Believed to be Australia's longest-serving flight nurse, Ms Roberts is retiring from the NSW Air Ambulance this weekend after 37 years in the job.

"I could cry because it's mixed emotions. I really love my job but there's a life out there," she said.

She said it was her patients from across rural and regional NSW that she would miss the most.

The Air Ambulance service has changed a lot over the past 37 years. ( Supplied )

"Country people are just so resilient. You know out in country towns they might have to wait for a couple of weeks to even see a GP," she said.

"Whereas here in Sydney, dreadful to say but sometimes they'll call an ambulance almost for a Band-Aid."

Ms Roberts said she and her colleagues dealt with a wide range of medical issues each day, from cardiac problems to obstetrics and farm accidents.

"You have burns, gun shot wounds, penetrating eye injuries, it's a mixture of things," she said.

She said another important part of the job was transporting patients back to regional areas so they could die at home.

"You have a chat and hold their hand … it makes you realise how lucky you are in life."

Colleagues pays tribute to much loved nurse

Ms Roberts' boss, Superintendent Graeme Field, said the role of a flight nurse was extremely challenging.

"It's not like working in the back of an ambulance where you can pull over to the side of the road if something goes wrong," he said.

"You're up in the air, you have to be able to think on your feet, you have to be very knowledgeable."

Superintendent Field said Ms Roberts would be missed by her patients and her colleagues.

"It takes a special kind of person to be a flight nurse and a really special person to do it for nearly four decades."

"And Maureen is a perfect example of someone who displays compassion continuously and can really build up a great rapport with her patients."