"Uncle met you at the airport."
Translation:Onkel møtte deg på flyplassen.
"Lufthavn" is often part of the official name of an airport; Oslo Lufthavn and so on. So if you're at an airport, or ordering a ticket, or reading a news article that is probably what you're going to encounter.
When just referring to an airport, without using its full name, "flyplass" is more common.