The schedule is out.
The aircraft is not.

You have published a schedule and sold seats against an aircraft that has not arrived. Leased capacity bridges the gap without cancelling, and it is priced as a defined period rather than as an open ended commitment you cannot exit.

The structural picture explains why this keeps happening. Airbus delivered 793 aircraft in 2025 and closed the year with a record backlog of 8,754, which is roughly eleven years of production at that rate. Slots move because there is no slack.