UK Flight Chaos Enters Second Day After Air Traffic Control Failure

Travelers across Britain faced a second day of delays and cancellations Wednesday after a technical failure at the country's air traffic control provider grounded hundreds of flights and left some passengers stranded on aircraft for more than five hours the previous afternoon.

NATS, which manages UK airspace, first flagged the problem at 1:46 p.m. local time Tuesday, saying in a statement that "a technical issue" in the system that processes flight plans was "causing some disruption to flight departures." The company restricted the flow of outbound flights while engineers worked on the fault, confirmed a fix was in place by 4:40 p.m., and said by 7:30 p.m. the system itself was operating normally. But NATS warned the recovery from the backlog would take considerably longer, describing it in a later update as "a very complex recovery." By Wednesday morning the company said in a further statement that "our operations are stable and we continue to work closely with airlines and airports to support their recovery from the ongoing disruption to their operations."

Thousands of passengers affected

The scale of the disruption was significant even by the standards of a summer that has already seen repeated air traffic delays across Europe. Aviation tracker Flightradar24 recorded roughly 1,300 cancellations to or from UK airports on Tuesday, according to CNN, with Heathrow, Gatwick, Manchester and Stansted among the hardest hit. Ryanair said the outage disrupted roughly 65,000 of its passengers. Al Jazeera reported that some aircraft that had already landed at Heathrow were unable to reach a gate because all stands were occupied, leaving passengers waiting on taxiways for five hours or longer before they could disembark.

NATS has not said publicly what caused the software fault, describing it only as a technical problem within the flight-plan processing system rather than an issue with radar or air traffic controllers' ability to separate aircraft safely. The company apologized to passengers, airlines and airports affected and said a full investigation into the root cause was still to come.

Ripple effects continue

Even after NATS declared its own systems stable, airlines were left scrambling to reposition aircraft and crews that had been thrown out of position by Tuesday's ground stops, a process that typically takes longer than the original outage itself. Knock-on delays and a smaller number of cancellations were expected to continue at major UK hubs into Wednesday and possibly beyond, particularly for long-haul routes where a single delayed aircraft can disrupt a following rotation.

The incident is the latest in a series of high-profile air traffic control failures in Europe in recent years, and is likely to renew scrutiny of the resilience of NATS's technology, which faced similar criticism after a 2023 outage stranded tens of thousands of travelers over a bank holiday weekend. Passengers affected by Tuesday's and Wednesday's cancellations are entitled to rebooking or refunds under UK air passenger rights rules, and airlines said they were working through a backlog of claims.

For travelers with flights booked through UK airports later this week, airlines have generally advised checking flight status directly before setting out, since knock-on delays can affect aircraft and crew rotations on routes that had nothing to do with Tuesday's original fault. Neither NATS nor the affected airlines have yet estimated the financial cost of the disruption, and it is not yet clear whether Wednesday's more limited delays will fully clear by the end of the week.