Hundreds of flights delayed as UK air traffic control suffers sudden system failure

As per latest update, major airports across the UK faced significant flight disruptions and delays following a technical failure within the National Air Traffic Services (NATS) system.

"Airports south of Manchester are broadly unaffected, however flights heading north and flights departing Scottish airports are currently subject to some delay,” NATS said in a statement.

Root cause:

NATS reported that the disruption stemmed from a legacy software defect triggered during a narrow, one-millisecond window when a manual aircraft identification "squawk" code request was interrupted by a higher-priority task.

The system glitch corrupted flight data processing, forcing air traffic controllers to temporarily restrict UK airspace capacity and handle processes manually.

NATS said Monday’s delays were "unrelated to the issue two weeks ago", when around 2,000 flights were cancelled due to a software defect.

Widespread delays:

Major traveling hubs including London Heathrow, Gatwick, and Edinburgh, experienced substantial backlogs, resulting in hundreds of flight delays, diversions, and cancellations that impacted hundreds of thousands of passengers.

NATS confirmed that safety was maintained at all times and that temporary mitigations were deployed while a permanent software fix underwent rigorous safety testing.

However, the incident prompted intense criticism from airlines and an independent review ordered by the government.