Originally Posted by
HPN-HRL
It's even harder that FCfree makes out.
I wasted some time a few summers ago making spreadsheets for various WN schedules; it is easy to track the change in flight number when a flight number terminates at a small station, but when the flight number terminates at MDW or BWI (or LAS, etc.), there could easily be 5 possible new flight numbers that the original plane could be continuing on. So I wasted lots more time looking at WN's flight status indicator, trying to match up planes by the gates of incoming vs. outgoing flights. That worked great - except that when I looked at the same flight numbers on different days (in the same airport during the same WN schedule), they would connect differently!
I'll add a picture of my work if I can figure out how to post the image.
I do this sort of thing all the time for my own amusement (yes, I do have a life; this is just part of it!), for different airlines. I also have some knowledge of airline scheduling practices, although it hasn't helped me to get hired into such a position (because I only have knowledge, not experience).
What you describe is a common occurrence. The general practice at many airlines -- and I don't know whether or not WN is one -- is to draft the schedule so that every airplane flies the entire routing for the type before it starts the cycle over. As a much-simplified example, consider if WN had just two routes, SFO-MDW and LAX-MDW, and two airplanes to fly them. Assume both planes start the day at MDW. A typical airline would schedule one of them MDW-SFO-MDW-LAX-MDW or MDW-SFO-MDW-SFO-MDW, and the other MDW-LAX-MDW-SFO-MDW or MDW-LAX-MDW-LAX-MDW. The important point, though, is that on the second day they would trade routings. This helps even out flying time for maintenance planning.
Of course, there is also the problem that the real world intervenes and usually the plan is shot by the end of the first day it's in place. Weather and maintenance delays occur, and planes get shifted to other routes than those that were planned. From then on the plan will be the general basis, but maintenance needs can preempt the plan.