Originally Posted by
Stranger
I cannot think of a good reason for them to do the change. Normally they introduce a 2xxx flight number when one flight gets delayed to the next day so as to avoid having two flight with same number on the same day, but as far as I know that was not the case.
I've seen it many times when it departed same day, same time as scheduled. But there was always something substantial about the change, like a change in gauge. If they downgauge a 77W to a 320, they're massively overbooked. If they cancel 123 on a 77W and created 2123 on a 320, they can then just rebook all the pax onto other flights as well.