high-altitude sickness

エベレストに登ったドイツ人の男性が下山途中で亡くなりました。

Dutch Climber Dies on Way Back From Everest Summit

A 35-year-old Dutch man suffering from high-altitude sickness died on his way back from Mount Everest's summit in the first death reported this year on the world's highest mountain, an expedition organizer said Saturday.

Eric Arnold died near the South Col on Friday night, said Pasang Phurba of the Seven Summit Treks agency in Kathmandu.

Arnold had enough bottled oxygen with him as well as climbing partners, but he complained of getting weak and died before he was able to come down to a lower altitude, Phurba said.

He said that more details were not available because of poor communication with the crew on the mountain, and that it would take days and several people to bring Arnold's body down the slopes.

以下略

http://abcnews.go.com/International/wireStory/dutch-climber-dies-back-everest-summit-39273696

記事の中で気になった表現は、"high-altitude sickness"です。

文脈的に、山に関する病気なので、「高山病」と予想できます。
実際に、『ジーニアス英和辞典』第4版(大修館)で"altitude"を引くと、"altitude sickness"で「高山飛行病、高山病」という意味がありました。
また、"altitude"には、1.「(山・飛行機などの)高さ、標高、高度、海抜」や、2.「高所、高地」や、3.「高い地位、高位」などの意味があり、
"fly at a low altitude"で、「低空飛行をする」という意味があります。(Akim)