Thats when you ask the user to add another airport with the same name and -2 at the end. Add a "has moved" field!

Now you have to specify whether or not it’s moved during queries (and what if it moves again?) There’s probably a more elegant way I’m not thinking of, but standard created_at and updated_at fields would work: if a given date is <= the move date, it’s the original airport, else the new one. Rinse and repeat if it moves again.