Thousands of passengers have been subjected to lengthy delays and cancellations as a result of a “technical issue” with UK air traffic control systems.
People are stranded in the UK and overseas as a result of National Air Traffic Services limiting the number of flights that may land.
Despite the fact that the problem was resolved within hours, airlines and airports warned that “significant delays” remained.
According to one traveler, her afternoon flight was not scheduled to depart until after midnight.
There have been fears that part of the fallout might persist for days.
Heathrow said late on Monday evening that schedules remained significantly disrupted, adding that people travelling on Tuesday should contact their airline before heading to the airport.
Gatwick Airport said it was planning to operate a normal schedule on Tuesday, but advised passengers to check the status of their flight with their airline before going to the airport.
London Luton Airport also said on Monday evening that flights across UK airspace remained subject to delays and cancellation, and people should check with their airline for the status of their flight.