London's Gatwick Airport suspended all flights on Wednesday due to "an air traffic control systems issue" in its control tower, it said.
Britain's second-biggest air hub announced the disruption just before 6:00 pm local time (1700 GMT), saying it was trying to fix the problem urgently.
"Due to an air traffic control systems issue in Gatwick's control tower, flights are currently suspended," the airport said on Twitter.
It apologised to passengers and advised them to check flight information with their airlines.
"We are working with ANS, our air traffic control provider, to rectify this issue as quickly as possible," the statement added, referring to Air Navigation Solutions (ANS), a private company that has controlled plane movements at the airport since 2016.
Gatwick, around 30 miles (48 kilometres south of the British capital, made headlines last December after closing its runway repeatedly due to reports of mystery drone sightings nearby, impacting nearly 140,000 passengers.
The airport,the eighth-busiest in Europe, serves numerous low-cost carriers and is EasyJet's biggest hub.