[kjellsbells]

In HN terms: imagine your assets are encoded in an array or list. Movement is represented by shifting elements right or left.

Most airlines are hub and spoke. Elements shift right (planes leave the hub) then shift left (return). Sometimes they shift two places right. If something disrupts this, like, a plane is stuck in [1] when it needs to be in [0], its generally recoverable when the event clears, or, you can use one of those 2 step moves in another flight to pick up stranded passengers on your way back to the starting position [0].

Southwest operate a point to point model. Assets start at [0] and have to traverse every point on the list through to [N] to succeed. N can be 3, 4 or higher. You can imagine what happens if a disruption happens in the middle of this list. Everybody upstream of the break is left planeless, everybody downstream who wants to go up cant make it further than the airport before the break, and everybody at the breakpoint is miserable.

So Southwest then fallback to a new scheduling model for which their system was not designed. Its like having a graph traversal system and trying to get it to solve matrix equations. Yeah, there are some similarities, but its not really the same.