Task: Text to Code
Input (English): SQL: SELECT T1.AirportName FROM airports AS T1 WHERE T1.AirportCode NOT IN ( SELECT T2.DestAirport FROM flights AS T2 )
Feedback: Also mention " or source airport in step 1.
Output (English): SELECT AirportName FROM Airports WHERE AirportCode NOT IN (SELECT SourceAirport FROM Flights UNION SELECT DestAirport FROM Flights)