I just had this though about how hot swapping could be done, i don't know if you are working on it at the moment or not but just wanted to let people know. It is quite a primitive system, basically when you view an individual aircraft by clicking its number there would be some extra options 1 for each route the is operated by the aircraft the second and third are on the right hand side in the infos bit by the sell and lease options. The option by each of the routes is "save route" the options on the right hand side are " save all routes" and " load routes basically when you click the save route button or the save all routes they are entered into some kind of storage system that saves route, frequency, ticket price and flight number etc altogether, and hot links it to the plane they were saved from as a permanent connection so that if you have to alter the frequency, ticket price etc it will remember the changes without you needing to do this. The hot link feature could be a premium feature if need be. Also when you click the close route or close all routes buttons as well as recreate route there would be an option to save route so you can close and save simultaneously. When you click the "load routes button" you get a list of every route on this menu there is a colour code of 4 colours Green means you can add it, Red means you can't, Orange means It is assigned to another aircraft but can't be used and Blue means it is assigned to another aircraft but can be used by this aircraft. Each flight has a square tick box in front of it not a round select box and as you tick each one it removes the amount of time spare that the aircraft has and as this happens the other flights change colour accordingly once you are happy with what you have selected you select Load at the bottom and the flights are transfered to the plane. A method of organisation could also be put in so that you can set it so you only view certain routes or routes from certain planes etc.
Once again sorry for long post, if you want me to clarify anything just say and i will try my best.