> One important component is slack. Every airline at every airport should have a certain number of crews and airplanes capable of providing service in place of

> One important component is slack. Every airline at every airport should have a certain number of crews and airplanes capable of providing service in place of a delayed flight. Airlines have crew on "reserve" at all times near bases to handle this problem. They are being paid to sit around and not actually work unless called in. Pilots love to try to get on the reserve list for obvious reasons. I don't know how Southwest handles reserve, since they don't have "bases" like other airlines do.