NATS Computer Failure Grounds Hundreds of UK Flights, Backlog Stretches Into Wednesday

Britain's air traffic control system broke down again on Tuesday, September 8, and by evening the damage had piled up: hundreds of cancelled flights, tens of thousands of stranded passengers, and airline executives publicly demanding someone lose their job.

The trouble started around lunchtime UK time when departures at Heathrow began getting held on the ground, according to reporting that tracked the day's timeline. NATS, the company that manages UK airspace, issued its first public update at 1:46pm, saying it was investigating "a technical issue" affecting departures.

By mid-afternoon the fault had a name. "We have identified that the issue was in our flight processing system," NATS said in a statement carried by CNBC and the Times of India. "Our engineers are on site and working urgently to resume normal operations as quickly as possible. Flights are still departing and airspace is open, but recovery will take some time."

Eurocontrol, Europe's air traffic coordinator, went further and temporarily suspended arrivals at Heathrow and Gatwick, diverting some inbound flights to Brussels, Amsterdam, Paris and Düsseldorf, with restrictions on London-bound traffic set to remain until 9pm.

The numbers kept climbing all day

Early tallies from Flightradar24 showed around 300 cancellations by mid-afternoon. By 6:30pm, that figure had roughly doubled to 625 cancelled flights to and from UK airports, according to the Guardian's live coverage. By evening, the Evening Standard cited Flightradar24 putting the number at 875, with more than 750 additional flights delayed between Heathrow and Gatwick alone. The Telegraph later reported the cancellation count had passed 1,000 for the day.

These escalating counts aren't contradictory outlets disagreeing. They're the same rolling tracker at different points in a fast-moving day. A reader jumping between two of these reports at different times could easily think the numbers don't match.

FlightAware data cited by CNBC and the Times of India showed roughly 100 cancellations and 367 delays at Heathrow specifically, with Gatwick logging about 250 delayed flights, or 31% of its schedule. Manchester, Birmingham, Stansted, London City, Luton, Aberdeen, Glasgow and Edinburgh all reported disruption, as did Belfast, Jersey, the Isle of Man and Dublin.

British Airways said it had to cancel or divert more than 100 flights. EasyJet said the failure was causing delays "across Europe." British Airways put it plainly in a statement: "This is entirely out of our control and we're in touch with our customers whilst our teams work to get them on their way as quickly as possible."

NATS says it's fixed. Passengers say it doesn't feel that way

NATS said it implemented a fix around 4:59pm and that the system was "starting to recover." By 7:30pm the company said the technical issue was resolved. But in a follow-up post on X, NATS acknowledged the obvious: "Recovery from today's system issue has taken longer than we had hoped... We are truly sorry for the ongoing flight disruption. We know this is hugely frustrating and apologise unreservedly."

Fixing the software doesn't put planes and crews back where they need to be. Aircraft rotations were scrambled across the network, and multiple carriers warned the backlog could stretch into Wednesday, September 9. Major London airports said flights would be allowed to operate through the night to help clear it.

The human cost showed up in individual stories. Amanda Dick-Cleland, 63, was booked on a Gatwick-to-Ibiza flight for a friend's birthday trip; her replacement flight, offered by British Airways, wasn't until Saturday, according to the Telegraph. An Ohio couple, Priya Pandit and Ishan Bhandari, told the Independent they'd now arrive more than 24 hours late to meet family in Istanbul, after finding Heathrow-area hotels fully booked.

Third strike for NATS in three years, and airlines are furious

This is not NATS's first meltdown. A 2023 flight-plan processing failure caused chaos that airline executives said cost them more than £100 million ($135.49 million) in refunds and compensation, according to CNBC. Britain's aviation regulator subsequently told NATS it needed to overhaul its contingency planning. In July 2025, a separate radar-related issue disrupted flights for more than four hours at Heathrow and other London airports.

After Tuesday's failure, Ryanair called for NATS chief executive Martin Rolfe to resign, according to the Telegraph. Wizz Air separately called the provider "not fit for purpose," per the Independent. Neither NATS nor the UK government has announced any leadership or structural changes in response, and NATS has not said publicly what specific component of its flight processing system failed or why.

The open question hanging over Tuesday's chaos is whether, after three major failures in three years and a regulator-ordered review that followed the 2023 incident, NATS's contingency systems—the ones the Civil Aviation Authority flagged as inadequate after the last outage—actually held up under pressure or failed again.