Gatwick Airport has reopened its runways after flights were suspended from shortly after 9pm on Wednesday until 3am on Thursday following reports of two drones flying over the airfield.
Police and aviation authorities were still investigating into the early hours of Thursday as incoming fights were diverted to other locations in Britain.
A police helicopter was called in after two unmanned drones were reportedly sighted near a runway, forcing the airport to halt all flights and warn of possible knock-on disruption on Thursday.
Passengers said on social media that flights had been forced to head to a number of other UK and European airports, including London Heathrow, Stansted, Luton, Manchester, Cardiff, Liverpool and Amsterdam.
Flight radar information also showed aircraft holding away from the airport before being diverted, while dozens of takeoffs were halted.
Passenger John Belo, said: “Plane should have departed an hour ago from Gatwick Airport – captain confirmed there are reports of a drone in the area… still waiting.”
Twitter user Seun Olayanju posted: “@AerLingus currently stuck at Gatwick waiting for the heavily delayed E10249 to Dublin. Please can you confirm if the flight will run tonight?”