UK Air-Traffic Outage Caused by Radar Canceled 150 Flights

The air-traffic control outage that disrupted UK flights on Wednesday afternoon was caused by an unspecified radar-related issue, leading to more than 150 canceled flights in one of the busiest travel periods of the year.

The service interruption resulted in the cancellation of 84 departing flights and 71 arrivals across the UK, according to data from Cirium. Some flights were diverted to other European airports, while London Heathrow, the country’s biggest hub, had the most disruptions with more than 45 flights called off, the aviation data provider said.

The latest breakdown has caught the attention of the UK government, with Transport Secretary Heidi Alexander posting on that she met NATS Chief Executive Officer Martin Rolfe on Thursday to understand what happened and was assured it was an isolated event. UK Prime Minister Keir Starmer also weighed in on the topic, saying Alexander is “getting to the bottom of it.”

“The frustration of holiday makers will be palpable, and of course, the airline carriers,” Starmer told reporters in Swindon on Thursday. “It was dealt with relatively quickly. But that doesn’t take away from the fact that it impacted many, many people.”

The technical glitch at NATS, a major facility for air-traffic control in the UK, forced authorities to temporarily limit the number of movements into London on Wednesday afternoon, grounding flights across a large swathe of the country, including at airports from London Gatwick and City to Birmingham and Manchester further north.

“This was a radar related issue which was resolved by quickly switching to the back up system, during which time we reduced traffic to ensure safety,” a NATS spokeswoman said. “There is no evidence that this was cyber related.”

Flights restarted in the afternoon after engineers at the NATS Swanwick site restored the system. But the outage hit air traffic during the busiest summer holiday period, hobbling flights for airlines including British Airways and discount specialist EasyJet Plc.

The disruption from the air traffic control failure was “extremely disappointing,” EasyJet Chief Operating Officer David Morgan said in a statement. Ryanair Holdings Plc called for Rolfe to resign over the outage.

The latest fault follows a full-day outage at Heathrow airport in March after a fire at a substation cut electricity supply to the sprawling hub. Two years ago, the UK airspace temporarily shut down because of an air traffic control system glitch. The issue was fixed after a few hours but caused heavy disruption to departures and arrivals across the country.

The Swanwick operations room manages the en-route airspace over England and Wales up to the Scottish border as well as lower-altitude traffic to and from London’s airports, equal to about 2.5 million flights or 250 million passengers in the UK airspace.

The center, which was inaugurated in 2002, and on which Lockheed Martin Corp. was prime contractor, was designed to give NATS 30% more capacity, helping it handle 3 million flights a year by 2020 from about 2 million when it opened.

Photograph: Passengers wait at Terminal 5 following an air traffic control (ATC) fault that caused a major disruption at Heathrow Airport in London on July 30, 2025. Photo credit: Jonathan Brady/PA Images/Getty Images