Departures at Heathrow were temporarily stopped after a drone was reported to have been sighted.
Flights from the west London airport resumed about an hour after police said a drone had been seen.
A Heathrow spokeswoman had said it was a “precautionary measure” to “prevent any threat to operational safety”.
It comes after last month’s disruption at Gatwick Airport which saw thousands of people stranded when drones were sighted.
The spokeswoman said: “We continue to