I have playing AIRLINE for since 4.0, but I have still have some things I haven't figured out.
When I use multiple Service Levels I can't most of the times change Service Level for different routes, when I click on the segment I'd like to change nothing happends most of the time, some time I get the screen where I can change service level and prices for the segment, but mostly not! It's happened both when the game I freshly started or a couple of years into the game, kind of sucks being stuck with only one Service Level for all of your flights!
Then I wonder if there any 3rd party programs that can assist with scheduling, it getting a little out of hand when you have to keep routes, departure, arrival time for 50+ aircrafts in you head.
But anyhow, I love the game!