Gatwick Airport was shut for 6 hours overnight, after reports of two drones flying over the airfield.
All flights to and from the airport were suspended between 9:01 pm and 1:03am, with planes being diverted to other UK airports, including Manchester, Luton and Stanstead.
On social media, passengers reported being delayed on the runway for over an hour as they waited for updates from the pilot.
British Airways confirmed that "Gatwick have stopped all arrivals and departures due to a drone".
Gatwick Airport tweeted tweeted that it was working with Sussex Police to investigate the incident, and apologised to passengers for the inconvenience, stressing that safety was "our foremost priority".
Delays and diversions are expected to continue on Thursday.