Air Traffic Control System management
Air traffic control system is the computer system that air traffic controllers use to keep track of the aircraft they are controlling.

The system processes data from the primary and especially a secondary radar and displays them in suitable fashion for easy understanding by the controllers. The radar processing itself is not interesting for database class. But there is a bunch of information about each aircraft that needs to be remembered and associated with it's radar image:


The assigned transponder 4 octal digit code (usually called "squawk"). This is a code the secondary radar receives from the aircraft used to associate the data to the correct radar return.
Identification, also used as callsign. It is registration number or flight number (sometimes internal company flight number that is different from what they show in time tables)
Aircraft type

The aircraft type is needed so the controller knows the performance of the aircraft, so it needs associated performance data like maximum speed, approach speed, maximum altitude etc.

Flight plan. This needs to contain:

Start and destination airports
Preferred cruise altitude and speed
List of waypoints

You may consider current clearance limit (altitude and waypoint); I am not sure whether the current systems include it or not.