UK air traffic outage reportedly linked to flight data from military aircraft

The UK’s National Air Traffic Services (Nats) outage may have been caused by a military aircraft’s flight plan, the Financial Times reported, citing four people briefed on the incident. The system was unavailable for about four hours, disrupting air travel across the country.

More than 2,000 flights were cancelled on Tuesday, affecting hundreds of thousands of passengers. Some aircraft carrying passengers waited for information for more than four hours, while flights bound for the UK were diverted, including to Germany.

The newspaper said the military flight plan contained “spurious” data that triggered the failure in Nats systems. The Ministry of Defence said it saw no indication of an error by the military, but would not comment further before the Nats investigation was complete.

Reviews after the four-hour outage

Nats chief executive Martin Rolfe met transport secretary Heidi Alexander on Wednesday. Alexander said she did not believe the incident was unavoidable and was understood to have given Rolfe a week to report on its causes; the Civil Aviation Authority will also conduct an independent review.

Rolfe rejected an initially suspected cyber-attack. He said Nats had not experienced an incident of the same kind more than once and had not seen anything similar in its 50-year history.

Criticism over system backups

During the crisis, Nats operations officer Kathryn Leahy told airport and airline managers that the flight-processing system had no dedicated backup. The service is undergoing a complete systems overhaul, while duplicating the large volume of stored data would be extremely costly, she said.

The outage was the most serious disruption to British commercial airspace since August 2023, when a technical problem delayed almost 1,600 flights. After that incident, the regulator issued 34 recommendations, all of which Nats was reported to have implemented.

Several airline executives called for Rolfe to resign or be dismissed. Ryanair chief executive Michael O’Leary said Rolfe’s position was untenable and argued that further investigations and promises to improve resilience were unnecessary.

Passengers affected by the disruption were unlikely to qualify for compensation because the delays were understood to involve “extraordinary circumstances.”