Speaking of planes crashing to the ground...

Here's a lengthy but interesting perspective on why so many flights are late or delayed.

Any runway has a finite capacity. The key to understanding this is in understanding time. Only one aircraft is allowed to use the runway at any time. It takes a certain amount of time for a departing aircraft to taxi onto a runway, accelerate to flying speed and lift off. Likewise, it takes a certain amount of time for an arriving aircraft to touch down, slow down and taxi off the runway. The time it takes the typical airliner to do either one -- land or takeoff -- is roughly one minute.

The math is as simple as it is inescapable. Roughly 60 airliners can use a runway in one hour if conditions are absolutely perfect. It is physically impossible to improve that number. However, it can get a lot worse.