Can a helicopter land on Mount Everest?

On 14 May 2005, Didier Delsalle flew an AS350 B3 from Lukla to the summit of Everest and landed on it. He held the aircraft on the snow for close to four minutes — long enough that the Fédération Aéronautique Internationale would ratify it as a landing rather than a touch — then flew back down. He did it a second time the next day, because a record needs repeating to be certified.

The aircraft was a production machine, but stripped: no passenger seats, no cargo, the minimum fuel that would get it up and back. Delsalle flew it alone. He described the summit air as barely able to hold the rotor, and the risk as being less about the landing than about whether the engine would produce enough power to leave again.

Nobody has repeated it in the two decades since, and there is no commercial reason to. It was a test flight that proved a point about the B3's high-altitude engine, and the point has stayed proved.

A rotor makes lift by throwing air downwards. At 8,849 m there is roughly a third as much air per cubic metre as at sea level, so the same rotor turning at the same speed produces roughly a third of the lift. The engine is fighting the same problem from the other end — less oxygen means less power to turn the rotor with.

Both curves fall away together, and they cross somewhere. That crossing point is the aircraft's ceiling, and for most helicopters flying in Nepal it sits thousands of metres below the summit of Everest. The five-passenger machine that lifts easily out of Kathmandu at 1,400 m may manage two people at 5,500 m, which is why high landings are flown in shuttles.

Weather closes what physics leaves open. Even if the aircraft has the performance, the summit spends most of the year inside a 160 km/h jet stream, and there is no version of that in which a landing is sensible.

The commercially available answer is a good deal less dramatic than a summit landing, and considerably more useful: you can be looking at the south face of Everest from a helipad at 5,545 m before most of Kathmandu has had breakfast.

Flying over is a much lower bar than landing on, and it has been done — Delsalle's flight passed over the summit before it settled onto it, and high-altitude aircraft transit the region. But no commercial tour overflies the summit of Everest, and you should be sceptical of any operator that says it will.

Sightseeing flights hold at a viewing distance in the Khumbu, typically between 5,500 m and 6,000 m, which is where the view is anyway: from directly above, Everest looks like a ridge. From Kala Patthar it looks like Everest.

The genuinely impressive helicopter work on Everest is not sightseeing, it is evacuation. Landings at Camp 2, around 6,400 m, are flown when someone cannot come down on their own. Above that, crews use a longline — a cable slung beneath the aircraft with a rescuer or a harness on the end — because the machine cannot land but can hover just long enough.

The highest longline extractions on the mountain have been carried out at around 7,800 m. They need a specific aircraft, a specific pilot and a window in the weather, and not every operator in Nepal has any of the three.