Three flights have been diverted to Stansted Airport following reports of a possible drone sighting at Gatwick.
Two easyJet flights - one from Barcelona and one from Amsterdam - initially got sent to Stansted before taking off again to land at Gatwick.
A British Airways flight from Heraklion was also diverted.
All three passenger planes eventually landed at Gatwick more than 90 minutes after their scheduled arrival time.
A Gatwick spokesman said: "Gatwick investigated a report of an unconfirmed sighting of an object outside the airport's 5km exclusion zone today but - following a full assessment - the airport has remained fully operational throughout."
A Stansted spokesman said he did not expect any further diversions on Sunday.
Meanwhile there was some disruption for flyers travelling to and from the country's busiest airport after a large fire interrupted train services nearby.
London Fire Brigade said 10 fire engines and around 70 firefighters were called to the blaze at an old coal depot in Tavistock Road, West Drayton, three miles north of Heathrow.
A container, an industrial conveyor belt, 15 vans and three articulated lorries were alight, prompting train services in either direction serving the airport to be halted for a couple of hours.
A number of drone sightings forced Britain's second-busiest airport to shut down for 33 hours in the week leading up to Christmas, disrupting 140,000 passengers' journeys.
The chaos continued despite a huge police operation and the Army was eventually called to bring the incident under control.
Military anti-drone equipment, which can detect the flying machines and disable them by jamming radio signals, remained at the airport until March.
Gatwick and Heathrow are investing millions in their own systems to prevent future flight disruption.
