On this occasion, things did not go well. The beacon was activated at 10.15pm, but Otago Rescue Helicopter personnel were not told for almost two hours.
Reaching the coastline at Kakanui Point, the beacon continuing to call them northeast, Flett realised the severity of the situation.
"It became obvious that we were going to have to conduct a rescue operation over water."
The chopper was about 14km off the coast when it overflew the beacon location.
"So, we dropped a bit of height, swung around and made another approach to where it was pinging off. "It went behind us. So we lowered even more.
"Then, at probably less than 400 feet, our co-pilot spotted two heads in the water. It was like finding two needles in a haystack."
Flett had no way of knowing, of course, but that rescue operation was one-third of the way through what would become an illustrious, 28-year career as a senior intensive care paramedic with the Otago Rescue Helicopter Trust - flying thousands of missions to give the quickest possible, life-saving intervention and care to car crash victims, fishermen, intensive care patients, hunters, premature babies, trampers and many others in need throughout the lower South Island.
Born and raised in Milton, Fleet worked on his father's sheep and beef farm after leaving school. It was while attending a St John first aid course that he was shoulder-tapped to join the township's volunteer ambulance service.
"It was a busy little station, a bit of an eye-opener," he says.
"In those couple of years I certainly saw a reasonable amount of bad stuff."
In 1985, he left the farm and joined St John as a full-time ambulance officer, based in Dunedin.
"I thought it was quite an exciting career pathway ... It was something I could get my teeth into."
The next decade was busy. It included being called out, on November 13, 1990, to the David Gray massacre, at Aramoana, in which 14 people died.
"It was a very, very tragic thing."
In 1994, Flett began doing some rescue flights with the region's fledgling rescue helicopter service. It grew to the point, five years later, that being a rescue helicopter intensive care paramedic was his daily reality.
Each of Otago's rescue helicopters is crewed by a pilot and two intensive care paramedics.
When a call comes in, they are airborne within five minutes.
On the way to the job, the paramedics assist with communications and navigation. When they arrive, one paramedic is responsible for the care of the patient. The other acts as crewman, keeping the chopper and people a safe distance from each other, and then assisting with the patient.
Speed is essential.
Given they cover more than 66,500sq km, it can take up to an hour to get to the patient.
"We minimise the time at the scene," Flett says.
"We like to do what we can and then get them on board and continue treatment on the way to hospital.
"Anybody who has suffered severe trauma injury and they're bleeding internally ... that patient needs to be on the operating table as quickly as possible."
With so much coastline, the winch is an essential piece of rescue kit.
Sometimes Flett operates the winch. Other times he is dangling on the end of the wire.
The winch is technically challenging and requires excellent teamwork.
"You can imagine, if the stainless steel cable got fouled on the boat and the boat dropped away — that would pull the aircraft out of the air."
Flett was winch operator in January, 2009 when the rescue helicopter made a mercy dash deep into subantarctic waters to retrieve a cruise ship crewman who had suffered a severe hand injury.
The crew flew 715km from Invercargill to Campbell Island, refuelled, flew a further 100km, winched up the patient in heavy seas, refuelled and flew back to the mainland.
At the time, it was the furthest distance from the New Zealand shoreline that a helicopter rescue had been conducted.
"That made for a long day. The mission took about nine hours."
A calm exterior is a great asset, Flett says.
"I think that's the key ... You might quietly be apprehensive but you have to portray a certain air of confidence and ability.
"For the patient and their families, or the bystanders, you are the rescuer. So, you've got to portray a sense that you know what you're doing.
"There's not much that I haven't had to deal with. It comes with the territory."
During the return flight, the paramedics continue providing care. They are also in direct contact with the receiving hospital, giving updates so the hospital staff can make necessary preparations.
Flett took part in the rescue that was a catalyst for the creation of the Otago Rescue Helicopter Trust.
It was 1991. A hunter had fallen over a cliff high up Deep Stream, the Taieri River tributary that starts on the slopes of the Lammerlaw Range.
Just before dark, Flett was flown up in a Hughes 500 helicopter, simply as a quicker means of getting into the rugged back blocks. The patient was located and some care given. Those coming on four wheels eventually arrived. The next morning the patient was taken to hospital, but died of his injuries.
If a dedicated rescue helicopter and crew had been available, as was already the case elsewhere around the country, the whole job would have been "done and dusted within the hour".
"That was the catalyst for getting Graeme Gale and the likes of Ross Black together to push for a helicopter service in this district.
"That demonstrated there was a very clear need."
As the plan came together, Flett was asked to lead the project for St John, setting up the training and crewing of Otago's rescue helicopter service.
In 1994, on the day the service was launched, there were two callouts. The first one, for a walker with a broken ankle at Evansdale Glen, interrupted the official launch event at the Kitchener St helipad that was being attended by various dignitaries.
"Some people probably thought it was a bit staged, but it was the real thing."
Later that afternoon, there was a call-out to a lime-sower truck that had rolled near Lawrence.
The experience, for crew and patients, has improved with time.
The original aircraft was a Bell Jet Ranger 206, a helicopter never designed for emergency medical services. Now the Trust uses the Kawasaki BK117 and the state-of-the-art Air Bus H145.
"It's a great working environment for the paramedics. We can access the whole patient — compared with the Bell Jet Ranger where the patient's feet were down by the pilot's controls.
"There's enough room to do everything we need to. We provide advanced airway care, administer pain relief, monitor the patient's vital signs. And occasionally we might have to do CPR."
Equipment has been part of that improvement.
At first, the helicopters used medical gear from ambulances. Now it is purpose-built, from mechanical CPR devices and patient monitoring systems that can send data to doctors during flights, to ventilators and, as of three months ago, syringe pumps that dispense drug infusions and free up a pair of hands.
"We are well equipped. We can put four helicopters in the air, all equipped the same, at short notice."
The final months of 2004 were monumental for Flett.
In early September, in the Southern Ocean, he was winched down on to the fishing vessel Aoraki to assist a fisherman who had sustained horrific injuries when his lower body became caught in fish processing machinery.
For 18 hours, Flett stayed with the man in the cramped bowels of the ship, administering medicine, blood and pain relief. The fisherman was able to hear recordings of his family before he died.
The weight of being so remote from medical assistance was relieved by the knowledge of how many people were assisting elsewhere.
"I knew there was a cast of hundreds in the background pulling out all the stops.
"They even flew an Orion down to drop medical supplies including blood and drugs, at night.
"Something logistically so large that had an unfortunate outcome - it would have been nice to have a win."
Three months later, Flett was named North & South's New Zealander of the Year.
"I could've crawled under a rock," Flett says, still sounding bemused 17 years later.
"It was a very nice gesture. But ... yeah, I didn't think I was worthy of an accolade like that."
The magazine's editor said at the time that the intensive care paramedic's 20 years of service made him the stand-out winner. But Flett still thinks the national and international publicity that surrounded the Aoraki mission played a big part.
"I was just doing my job at the time. I was Johnny-on-the-spot. I was a bit gobsmacked really."
But if the word of the rescue helicopter service's founder and chief pilot Graeme Gale is any indication, Flett's recognition was, and is, well-deserved.
"He stands out as one of the most respected paramedics of all time, in my eyes," Gale told The Weekend Mix this week.
Having worked with Flett for almost three decades, Gale says he has always proved to be "an exceptional person ... someone who is clinically savvy and has the respect of his colleagues".
"Because, some of these jobs, you're under a lot of pressure in often very hostile terrain in adverse weather in the middle of the night, you need someone with a very calm head, very calm mind, who is going to execute the task in hand and play a very important role in getting us back safely. Doug was all of the above."
Flett took his role seriously, which was evidenced by the results, Gale added.
"And the skill set that he brings; there are a lot of people alive today who owe their life to Doug Flett."
He, and the rescue helicopter service, are simply "one cog in a big wheel", Flett says.
"We have a fantastic team of volunteer ambulance officers out in the region, the fire brigade, the police, the GPs, the primary care nurses - they all make a big difference before we get there.
"So, we come along and pick up that continuum of care. We aren't a standalone, save-the-world sort of operation, we're part of a big chain from the first person on the scene of the accident through to the trauma surgeon."
He is, however, pleased with what he has contributed and thankful for what the job has given him.
"I've always enjoyed the excitement of the job. I'm not an adrenaline junkie by any means, but I just enjoy helping people.
"Although we deal with it on a day-to-day basis, in someone's life it is a huge event for them or their families.
"When I leave here I'll feel very privileged and proud to have been part of something very worthwhile."
And leave is what he plans to do; at the end of the coming week.
"I wouldn't have missed it for the world, [but] I now want to take a quieter approach."
He is going back on the road with St John, as crew on the new rapid response unit that will provide intensive care paramedic support to road ambulance crews.
While that might not sound like a change of pace to most, Flett says that is what it will be.
"I'll have more time to spend with my family in this new role, which is quite important."
Constant, steady improvement has always been important to him.
As it was that midnight off the coast of Kakanui, searching for five fisherman lost for hours in icy waters after a failure in the under-resourced national rescue co-ordination system.
"To find two small heads in reasonably rough conditions - they were very lucky ... They wouldn't have lasted much longer," he says.
Flett lowered Benn on the wire to fish out the two survivors. They took them to Oamaru Hospital and then flew back out to search for the other three.
One body was recovered. The other two were never found.
A coronial inquest followed. As a result, a 24-7 operation, the Rescue Co-ordination Centre New Zealand, was set up.
"That was the job that highlighted the inadequacies of things as they were.
"What we had then and what we have now, it's like chalk and cheese. They're a professional organisation, fully funded and purpose-built.
"So, a certain amount of good came out of a bad situation."
