A technical glitch in the flight processing system at Britain's National Air Traffic Services disrupted thousands of flights on Tuesday and left lingering delays and cancellations across UK airports on Wednesday.

The issue began shortly after 1 p.m. BST on Tuesday when engineers detected a problem with the system responsible for handling flight data. NATS, which manages air traffic control for 15 UK airports, said safety was never compromised but confirmed the fault prevented normal operations for several hours. The problem was resolved around 4:40 p.m., yet recovery efforts extended well into the evening and the following day.

Flight tracking data showed more than 1,300 flights canceled on Tuesday at major hubs including Heathrow, Gatwick, Manchester, and Edinburgh. Airlines such as British Airways, easyJet, and Ryanair each canceled over 100 flights in some cases. Ryanair reported more than 65,000 passengers affected and 50 flights scrapped. Inbound flights were also held overseas, with some diverted to other European airports.

Disruption carried over to Wednesday, with Flightradar24 reporting around 250 additional cancellations, nearly all at Heathrow. Airlines warned of continued repositioning of aircraft and crews, leading to further schedule changes. Heathrow advised passengers to travel only if their flight was confirmed operating, while Gatwick noted operations would take time to normalize.

This marks the third major NATS system failure in just over three years, prompting renewed scrutiny of the public-private partnership and calls for accountability. Ryanair and other carriers questioned the system's reliability and urged government intervention. NATS chief executive Martin Rolfe stated he accepts full responsibility and is scheduled to meet Transport Secretary Heidi Alexander on Wednesday.

Passengers faced long queues, rebooking challenges, and uncertainty, with knock-on effects reported across Europe. NATS apologized for the inconvenience and emphasized efforts to clear the backlog as quickly as possible.