The altitude at which the co-pilot handed control of the plane to his colleague was below the minimum altitude considered safe to continue final descent.

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The Himalayan Rescue Association, a non-profit health organization that offers safety seminars to trekkers in Manang, warns that ascending more than 300 or 400 metres higher than the previous day's sleeping altitude is not safe, especially when you are above 3, 000 metres.

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The TSA says the scanners are safe, exposing people to about the same amount of radiation they would get by flying for about two minutes at altitude.

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