UK flights thrown into chaos by radar glitch: How a 20-minute fault caused days of disruption

File Photo - Passengers wait at Gatwick Airport, south of London, on August 29, 2023 after UK flights were delayed over a technical issue.

A widespread technical fault at the UK’s National Air Traffic Services (NATS) control centre grounded flights across the nation on Wednesday, triggering travel disruption at the height of the summer holidays. While the issue was reportedly fixed within 20 minutes, passenger delays, grounded aircraft, and service interruptions are expected to ripple out for days.

What went wrong

Mid-afternoon, controllers at the Swanwick centre in Hampshire -- responsible for UK airspace above 24,500 feet -- lost radar visibility when screens abruptly stopped displaying flight data. Aircraft already airborne were diverted or held in mid-air, and triggering a freeze on new departures.

NATS confirmed the fault was “radar‑related” and engineers quickly activated a backup system, albeit at a reduced capacity: “It was resolved by quickly switching to the back-up system during which time we reduced traffic to ensure safety.” They later added, “Our systems are fully operational and air traffic capacity is returning to normal… Departures at all airports have resumed and we are working with affected airlines and airports to clear the backlog safely. We apologise to everyone affected by this issue.”

Airports and airlines in turmoil

Chaos rippled through major airports, especially Heathrow, where British Airways was forced to restrict movements to just 32 flights an hour, down from the usual 45. Other impacted airports included Gatwick, Manchester, Edinburgh, Birmingham, London City, and Cardiff.

London City saw dramatic disruptions, including a BA flight from Glasgow forced to divert mid-route. Across the network, passengers were stranded at airports or trapped on planes. Aircraft en route to the UK were sent to airports in Amsterdam, Paris, and Brussels.

By early evening, tracking firm Cirium reported over 80 cancellations with more delays mounting. Airlines spoke out: Ryanair, which operates throughout the UK, called the incident “utterly unacceptable,” while EasyJet demanded transparent answers: “While our priority today is supporting our customers, we will want to understand from NATS what steps they are taking to ensure issues don’t continue,” said David Morgan, its Chief Operating Officer.

Pressure mounts on NATS leadership

This latest failure follows a similar incident in August 2023, which affected over 700,000 travellers and cost airlines more than £100 million. Ryanair’s COO Neal McMahon levelled sharp criticism at the agency: “It is clear that no lessons have been learnt since the August ‘23 NATS system outage… passengers continue to suffer as a result of Martin Rolfe’s incompetence.” McMahon called for the resignation of NATS CEO Martin Rolfe. EasyJet joined calls for accountability, if in a more measured tone.

Transport Secretary Heidi Alexander warned of continuing delays and urged travellers to “check with individual airports for advice.” Liberal Democrat leader Sir Ed Davey demanded a government inquiry, warning that system failure, especially so soon after the previous outage, is “utterly unacceptable.” Lawmakers also urged investigations to rule out potential sabotage.

Why the disruption will last

Despite the swift technical resolution, industry experts warned that the impact will persist for days. Disrupted schedules, misaligned crew rotations, and scattered aircraft across Europe will complicate operations well into the weekend. And because this was an external failure, airlines are not obligated to offer compensation, though they must assist affected passengers with rebooking or accommodation.

NATS reassured the public: “Our engineers have now restored the system that was affected this afternoon. We are in the process of resuming normal operations… We continue to work closely with airline and airport customers to minimise disruption. We apologise for any inconvenience this has caused.”