tgrove is on the money. in some middle eastern countries, not to mention Nellis AFB, among others, the runways are more than 20,000 ft. because it can be 120 degrees F or more on the field. But there is no magic number, it depends on a lot of things, but having a long runway give you a little more room to finagle the other factors.

[This message has been edited by jet (edited 08-10-1999).]