Editor’s Note: Vertical recently visited Nepal to report on that country’s civil helicopter industry, which you can read more about in a future issue of the magazine. In the meantime, we’ve teamed up with Airbus Helicopters to bring you exclusive bonus content from Nepal, here and on social media. Find more at verticalmag.com/nepal and on Instagram @verticalmag and @airbus_helicopters.

It’s no exaggeration to say that the development of the Eurocopter (now Airbus Helicopters) AS350 B3 changed the landscape of helicopter operations in Nepal. Powerful enough to land and take off at previously inaccessible altitudes in the Himalayas, while retaining the versatility and economy that have made the AS350 series a bestseller, the B3 quickly became the most popular civil helicopter in Nepal. Today, that market is dominated by its successor, the AS350 B3e (now called the H125).

Given the importance of the model to operations in the High Himalayas, it’s fitting that the AS350 B3 proved its chops by touching down on the highest peak of them all: Sagarmāthā, better known outside of Nepal as Mount Everest.

“The idea was to prove to our customers all the margins they have while they’re using the helicopter in the normal certified envelope, compared to what the helicopter is capable of during the flight test,” explained Airbus Helicopters test pilot Didier Delsalle, who made the record-setting flight in a stripped-down production aircraft on May 14, 2005. With the AS350 B3 certified to a maximum operating altitude of 23,000 feet, it was clear that taking off from Mount Everest’s 29,029-foot (8,848-meter) summit would demonstrate a healthy safety margin.

While the achievement made international headlines at the time, you may not know the story behind it, particularly if you’ve joined the helicopter industry in the past 12 years. So we asked Delsalle to go back in time to 2005 and explain how his famous flight came together.


Decades in the Making

Delsalle started by going even further back in time, to 1972. That’s when legendary French aviator Jean Boulet, piloting an Aérospatiale SA 315 Lama, set the world record for the highest altitude flight in a helicopter at 12,442 m (40,820 ft). According to Delsalle, the achievement planted the seed of an idea that would only be realized three decades later.

“At the time, he thought about landing on Everest. But the company was not too keen to do that, and the type of helicopter was quite sensitive to power variations at high altitude [due] to the way the engine was governed,” Delsalle explained. “So it was not the helicopter to fly in the very turbulent environment at high altitude.”

Two years later, in 1974, Aérospatiale conducted the maiden flight of the first AS350 prototype. Over the next 30 years, the AS350 Écureuil or “Squirrel” — known in North America as the “AStar” — evolved through successively more powerful variants. In the early 2000s, Delsalle was assigned as a test pilot for the most powerful version yet, the AS350 B3, when it occurred to him that he might have found a helicopter with the potential to land on Everest.

“It was a kind of personal feeling with my flight test engineer at the time, Bernard Certain, that we had the capability to do that,” he recalled. “That was not planned at all at the time, but little by little the idea came in…”

Aérospatiale had by that point merged into Eurocopter, and the company initially discouraged the idea. But in 2004, when a new software version of the Turbomeca (now Safran Helicopter Engines) Arriel 2 engine performed better than expected, Delsalle broached the subject again. “I went back to the company and said we have to do that, we have the capability, and I will prove to you by some local tests here around the south of France that we have the capability to do that with an acceptable level of safety,” he said.

Those local tests started in April 2004 with an experimental flight up to 8,992 m (29,500 ft). They continued for a year, culminating in April 2005 with another experimental flight up to 10,211 m (33,500 ft), plus “time to climb” records to heights of 3,000, 6,000 and 9,000 m. Meanwhile, Delsalle was also busy organizing the logistics and clearances for his trip to Nepal, which “was quite difficult,” he said.

From Southern France to Eastern Nepal

By April 2005, Delsalle and his team of four mechanics and a ground engineer were ready. The helicopter was flown from France via cargo plane to New Delhi, India, where they reassembled it for the flight to Nepal. However, they narrowly escaped disaster when a sandstorm nearly destroyed the hangar they were working in. According to Delsalle, “it was only by chance that the helicopter had not been damaged. It was on the very first day we arrived, and we had been very lucky not to be hurt ourselves.”

Delsalle arrived with the aircraft in Kathmandu around the first of May, where he said his first step was to confirm his clearances with Nepal’s civil aviation authority. (This became a point of contention after the fact, when Nepal initially denied that Delsalle had secured appropriate permissions for the flight, and also that he had landed on Everest at all. Eurocopter would express regret for the “misunderstanding,” but stood by Delsalle, whose achievement was eventually certified by the Fédération Aéronautique Internationale, or FAI.)

From Kathmandu, Delsalle repositioned to Lukla, the remote mountain airport that is the jumping-off point for Everest climbers and trekkers. There, Delsalle and his team worked to prepare the helicopter for the record attempt — with a brief diversion to rescue two Japanese trekkers who were suffering from medical issues. Delsalle also began conducting recce flights to determine the best way of approaching the summit, quickly discovering that the path to the top wasn’t a simple one.

“On one side of the mountain, on the updraft side, I wasn’t able to approach the mountain because even taking out all of the power of the aircraft, I was still climbing,” he recalled. “But of course on the other side you had the downdraft side, and on this side even with maybe 60 knots on the airspeed indicator I was going backward . . . and the helicopter at full power was not powerful enough to counteract that.”

For Delsalle, making his way to the summit meant navigating the fine line between Everest’s updrafts and downdrafts. With the engine’s governing system operating outside its certified flight envelope, it was particularly essential that he find a path that would allow him to fly smoothly, without abrupt collective inputs. He made several approaches to the summit during his recce flights, but did not attempt a touchdown, “because I had felt that it was not the right time, the right feeling,” he recalled. “You have to of course be very comfortable in this kind of thing, and in fact you have to let the mountain accept you.”

Delsalle was also cognizant of the hazards that his rotor wash might pose to any climbers beneath him. In fact, his record-setting flight was timed to take advantage of a time period when there were no climbers near the summit.

“I had been lucky, and the climbers unlucky, because we had two days of bad weather, and all of the climbers had to go down because it was very, very bad weather,” he explained. “So just after the thunderstorm [passed], as soon as the summit was clear on the 14th of May, I tried my chance to go there, and I succeeded.”

On Top of the World

Delsalle recalled that the landing was a tricky one, due to the 65-knot winds and the lack of visual references.

“When you reach the summit you reach the updraft point, and of course the updraft winds have enough force to throw you away as soon as you put the collective down,” he said. “I had to stick my skids on the summit and push into the mountain to stay on the summit. Another big problem there is that you have no visual of the summit, and you have no specific cues, because you are on the highest point. You are in free air in fact, and you have to try to find where is the summit exactly.”


Not only that, Delsalle had his windows open to keep the windshield from icing up with the humidity of his breath (a problem that had plagued Boulet in 1972). The temperature was -35 C, and because Delsalle doesn’t like to fly with bulky flight suits, he was wearing only two layers of thermal undergarments, plus his flight suit. “But you know, in these conditions, you forget the cold,” he laughed. “You are so hot inside your mind, the cold is nothing.”

Touching skids was the hard part. Delsalle had no trouble when the time came to depart from the summit after 3 minutes and 50 seconds, nearly double the 2-minute skids-on-ground time required by FAI. After investing so much effort in reducing the weight of the aircraft — and even his own weight through dieting — Delsalle actually found that the helicopter was lighter than he would have preferred in the windy conditions. “It was very easy to take off,” he said. “I had just to pull a little bit on the collective and I went to flying very easily.”

Delsalle was understandably elated by his successful mission. But his mood changed when he returned to Lukla and downloaded what should have been the recording of his flight, necessary for proving his accomplishment to FAI.

“We had some very bad news, because when I checked on my computer . . . there were no recordings,” he said. “I remember I got a very bad temper at the time and I decided tomorrow morning I had to go again, before the climbers. In fact I went again on the 15th and I did it a second time.”

This time, the recording equipment worked. (In fact, it was later determined that the apparent absence of recordings from the first flight had been a software glitch, and the data from that flight was eventually recovered.)

Recognizing His Limits

Delsalle said he wouldn’t hesitate to make the flight again, as he was fully comfortable with the safety margins of the aircraft and the way in which the flight was conducted. “It was not crazy, everything was planned, and we had a good tool to do that, because the AS350 B3 is really a very powerful aircraft,” he said.

However, he came away from Nepal with a greater respect for Everest and the inherent challenges of flying helicopters on the highest mountain on Earth. Delsalle had been motivated, in part, by a desire to expand rescue capabilities for Everest climbers, hundreds of whom have died in their attempts to summit. He was not entirely disappointed in this hope, as in recent years an impressive number of Everest rescues have been conducted by AS350 B3 and H125 helicopters.

“But there are some limits, that was one of the conclusions of this mission,” Delsalle said, pointing out that Everest’s extreme winds and weather conditions make some rescues unacceptably risky, if not outright impossible. “Because in fact is it worth it to risk the life of a pilot and co-pilot to maybe rescue one [person] at such altitudes? Sometimes maybe it’s too dangerous, and you have to accept that it may not be possible.”