I have been going over this a lot, but have not yet been able to make my mind, do we need to inlcude classes like "Route" , "Schedule" and all or an assumption can be made that "Flight" will have all this information. Question is how much detail we need to go?
My suggestion is to KISS. Put in only the ones you felt is important without complicating the class diagram too much. I did explain some of the classes in my assumptions document which I did not show at all in my class diagram.