An option should be available on the airplane stand allowing you to divert individual or future flights to a different stand. This would allow you to rebuild a terminal or reroute baggage or anything else impacting the stand without canceling flights.
Currently if you want to change the baggage bay assignment you have to wait till the stand is not involved with a flight or other instances that require it to have no flights assigned to it. By temporarily or permanently diverting flights you can keep the terminal running smoothly.
Also this would mean if you have a large stand in an international zone allowing medium flights, you would have to reroute to another large stand in an international zone or whatever else is allow by the game to operate in the same conditions.
I do hope that A36 brings such options. As for emergency, something like this is really needed.
Otherwise players are forced to have a gate always ready for emergencies or have to cancel other flights or getting a completely delayed airport.
So a quick gate change option after a plane is already on it’s way would be the best.
And for long term planning: A mass change for all scheduled flights. The problem is when you schedule a 6x flight but the first one comes for example in 5 days, you can’t change the scheduled flights which are after day 6 in your calendar. You have to play several days to make all changes.
One of my main issues was adding a 2nd floor. I currently have gates on the 1st and 2nd because there can’t be any scheduled flights. Instead of cancelling the flights I turned off the auto schedule.
Also I believe cancelling flights should give penalties. Where diverting would be the alternative, avoiding penalties. It would allow you to remodel easier too.