One is up in the high Meseta of central Spain, at 1, 000m or more, with a very harsh climate and the other is in the mountains of Granada - again in a very harsh environment.

BBC: Last-stand Neanderthals queried

The new generation of planes are significantly cheaper to run than those currently flying, so a harsh economic climate may in fact encourage airlines to press on with renewing their fleets.

ECONOMIST: Making aircraft

Poverty and the harsh climate, particularly in Russia, play a part, as does the tradition of drinking.

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