A NATS system fault froze UK flight planning on 8 September.
National Air Traffic Services detected the fault in its flight data processing system at 13:46 BST. Engineers restricted departures across UK-controlled airspace while diagnosing. A fix was in place by 19:30, and NATS said in a later update that the recovery would be complex and would create difficulties across the aviation network. The Transport Secretary confirmed the cause was not a cyber attack. NATS said a full investigation will follow.
Around 1,700 flights were cancelled on 8 September, per subsequent airline and airport reporting. A further 150 or so were cancelled on the morning of 9 September as the backlog cleared. Fifteen UK airports were affected. Heathrow, Gatwick, Manchester and Birmingham took the heaviest disruption. Luton, Stansted, London City, Edinburgh, Glasgow, Aberdeen, Southampton, East Midlands and Belfast City also reported delays and cancellations. Ryanair said more than 65,000 of its passengers faced delays of up to eight hours.
Aviation International News reported that business aviation traffic was affected alongside scheduled operations. Slot restrictions applied to all users of the affected UK airspace, including operators moving into Luton, Stansted and London City. Departure and arrival rates at major gateways were curtailed for several hours on 8 September, and the backlog rolled into the following day.
This is the third UK-wide NATS disruption in three years, following the August 2023 outage and a July 2025 fault. Ryanair called for the resignation of NATS chief executive Martin Rolfe. Wizz Air said NATS was not fit for purpose. NATS apologised to passengers, airlines and airports. Owners with UK-inbound legs during the outage will see slot cascade effects across the coming days.
Source: NATS technical issue update, 8 September 2026; Aviation International News, 9 September 2026; Al Jazeera, 8 September 2026.