Answers

2016-02-29T13:48:19+05:30
Because there is no atmosphere for passenger as they flying high  in the sky ...so there is no scattering of light..... and the sky appear dark to the passenger

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2016-02-29T14:25:31+05:30
The sky appears dark to the passengers flying at very high altitude because at higher altitude the atmospheric medium is very rarer so the scattering of light taking place there is very low so the passengers at very high altitude see the sky as dark.
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pls mark as brainliest if it helped you