The Ministry of Defence has denied that a military aircraft was responsible for the National Air Traffic Services (NATS) system failure that grounded Heathrow flights for several days from 8 September, contradicting reports that named a military flight plan as the trigger.
A Financial Times report published on Friday said four sources familiar with the incident had blamed a flight plan submitted by a British military aircraft for introducing faulty data that caused the NATS system to fail. The BBC reported early on Saturday that an MoD spokesperson had rejected this. "We do not believe there's any indication of an error on the part of the military," the spokesperson said. "Because it's subject to a live NATS investigation, which is expected to conclude next week, it would be inappropriate for us to comment any further while that investigation is ongoing."
A NATS spokesperson told the BBC the organisation was "continuing to investigate the underlying cause" and that it would be "wrong to speculate while that work continues." The Independent reported the same denial, quoting NATS as saying a full technical investigation would follow.
Heathrow was among the hardest hit airports when the outage began on Tuesday 8 September, with cancelled flights and stranded passengers at Terminal 5 among the more than 2,000 cancellations recorded across the UK network within three days. The disruption prompted Ryanair's Michael O'Leary to call for NATS chief executive Martin Rolfe to resign, and Transport Secretary Heidi Alexander has told MPs she believes the failure was avoidable. She has ordered an independent probe by the Civil Aviation Authority, alongside NATS' own internal review due to report back this coming Wednesday.
The CAA has already indicated that passengers are unlikely to be entitled to compensation, since airlines are not generally liable for disruption caused by air traffic control failures rather than airline decisions. NATS has apologised for what is now its third major technical fault in three years, following a bank holiday shutdown in 2023 and a smaller outage in 2025.
Heathrow is currently reporting some delays to Saturday morning departures, though none linked to the NATS fault itself.
What this means for your journey: with the cause still under formal investigation and no compensation confirmed, allow extra time and keep a backup plan for getting to the terminal if you are flying from Heathrow in the coming weeks. Check current /public-transport/ options in case of any fresh disruption.