The pilot did not use runway or landing lights after takeoff, resulting in his spatial disorientation and the eventual crash.

The Tenzing-Hillary Airport in Lukla, Nepal, is not only 9,383 feet above sea level, but also has one of the world's steepest uphill runways — which ends in Himalaya-ringed nothingness.

But isn't such a long runway overkill? Denver Airport's size is more than just a matter of scale. Indeed, it's also a matter of safety. With an elevation of 5,430 feet above mean sea level ...