ideas.txt

- weather, need to avoid or big penalty or force altitude

- map has:
    - entry points
    - exit points
    - airways? but they don't need to be followed
    - runways?

- VIP planes
- military planes

- you can tell a plane to:
    - change direction / target
    - change speed
    - change altitude
    - follow airway

- score is total delays (minutes)