Probably you knew the example where H125 landed on Mount Everest (8848 m), and H145 highest landing was on Aconcagua (6962 m), almost 2000m difference.

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    $\begingroup$ The helicopter landing on the mount Everest was a special version of the H125, so the comparison is a bit unfair 😉 $\endgroup$
    – sophit
    Dec 16, 2023 at 14:15
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    $\begingroup$ @shophit "Delsalle used a virtually standard version of the Eurocopter, only removing unnecessary elements, such as passenger seats" - your link. I'd argue that's not a special version, nor even a modified one. Afaik those seats are removed more often, e g. for more cargo capacity when needed. Standard version, special configuration perhaps... $\endgroup$ Dec 17, 2023 at 7:24
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    $\begingroup$ @DaniëlvandenBerg: well 120kg less is 10% of the empty weight, which is a lot less. "Unnecessary elements" means also equipment not necessary for that particular mission, not only a couple of seats. So it was definitely a special configuration not flying normally. Just out of curiosity, a "special" version (this time with 200kg less equipment) reached almost 13'000m height. $\endgroup$
    – sophit
    Dec 18, 2023 at 16:59

1 Answer 1


Engines are heavy.

There is no market for a high altitude helicopter. Airliners fly high up because it lets them reach the destination quickly and cheaply. Helicopter buyers want to fly slowly near the ground. They buy a two engine helicopter to improve performance when an engine fails or to increase lift capacity. They do not buy a second engine to fly higher.

Buyers of heavy lift helicopters, which have multiple engines, want the higher power of multiple engines, but the helicopters are shaped to hold cargo. That's not the best shape for flying high.

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