[NOT A BUG] I had been coming back to the game without having to login

[Pegasus]

each time.  Today, for the first time since I first created my airline, I had to login and discovered my entire airline and fleet had disappeared and I cannot figure out why.  I have recreated my fleet and sent them out on routes, some with created routes, some using flight numbers and some by clicking on the arrows on the right hand side of the Fleet Management page (the page where you click on the arrows and get to a page with a selection of airports that you have gates of that the aircraft you are using can travel to).