A commercial airliner can weigh anywhere from 100,000 pounds to over a million pounds. It is astonishing how such gargantuan weight can not only take off from the ground, but also routinely fly long ...

Airplanes cruise at altitudes of several thousand feet above the ground for most parts of their journeys. If the sole purpose were to avoid buildings, airplanes wouldn't need to fly above 3,000 feet — ...