Airport on your route network is closing.
So when the airport is closed, do I have to do something manually or the computer guides you automatically to a new airport?
There is a search button. Use it.
However, since I am nice, the answer is that if the new airport opening near the closing airport is near enough, then the airline based their will have operations automatically removed. If you are not based their, then you will have to move your flight(s) manuelly. Eventaully all flights should be able to be moved automatically, but that is in the future. :)