Originally Posted by
joejones
This is just not true on many levels. One, aircraft are not scheduled to be constantly flying. They always have scheduled downtime to accommodate maintenance, irrops, charters, etc. Otherwise you'd have insane cascading delays and cancellations every time something went wrong. The major airlines basically have a pool of aircraft of certain types at each hub, including some spares, and can swap them out as needed for operational purposes. This is also why you usually don't see a tail number assigned to a flight until a day or two before it operates. Two, this is not fully automated; at the end of the day there are human operations personnel making the decisions. The computers just help with all the follow-on effects like crew scheduling and ensuring that there are sufficient numbers of aircraft at each hub.
Plenty of stories recently of major airlines pulling together one-off frequencies to handle stranded passengers during irrops, sometimes even ordering charters from other airlines. That is not somehow handled by SkyNet (yet).
The number of spare aircraft, maintenance, etc is all part of the scheduling programme. The idea is how many non-flying planes are needed to optimize the schedule and have the most planes possible in the air generating revenue. I was not inferring that all planes are in operation at all times.
Additionally, plane swaps are, for the most part, like for as-like as much as possible. Downgrades from domestic wide-bodies to narrow bodies occur as there are a lot less of them and a narrow-body cannot replace a wide-body on most wide-body routes, but the opposite is very rare.
In the context of this thread, putting a wide-body on a short domestic route that is generally low traffic, the system would likely not allow someone to swap out as they wish, unlike 30 years ago when it was manually operated.