Aircraft not arriving and the flight planner

[KingBirdy]

This person had a similar problem and Olof answered this:

Construction workers bug?

When stuff disappear when you load the game it is because the loading process was stopped due to a null reference issue being thrown, i.e. something broke before the persons could be processed by the system. We consider these kinds of bugs to be pretty serious which is why we really want to get them in and prioritize them!

So I suggest you file a bug report.
If you didn’t save the game after you loaded up your savegame should be fine I guess, just back it up or wait till the next hotfix to play.