The Ministry of Defence has rejected claims that a military aircraft was responsible for the technical failure that brought parts of Britain’s air traffic control system to a standstill last week.
The denial comes after reports that a flight plan submitted by a UK military aircraft contained what was described as “spurious” data, allegedly triggering a fault within the National Air Traffic Services (NATS) system.
The incident resulted in thousands of cancelled and disrupted flights, with more than 330,000 passengers affected by the four-hour outage on Tuesday.
Military Flight Linked to System Failure
According to four people familiar with the events who spoke to the Financial Times, NATS operations director Kathryn Leahy told aviation industry leaders that evening that a military flight plan had played a role in triggering the failure.
The alleged entry was said to have caused a glitch within the wider air traffic control system, leaving engineers struggling for several hours to restore normal operations.
However, the Ministry of Defence has firmly rejected suggestions that the military made an error.
“We do not believe there’s any indication of an error on the part of the military,” the ministry said.
It added that the matter remained under investigation by NATS and that it would be inappropriate to comment further until the inquiry was completed.
NATS Refuses to Speculate on Cause
NATS has also urged caution over claims about what caused the failure.
A spokesman said the technical problem had been resolved on Tuesday, but investigators were still working to establish the underlying cause.
“The problem was fixed on Tuesday, and we are continuing to investigate the underlying cause,” the spokesman said.
He added that it would be wrong to speculate while the investigation remained underway, with a full technical investigation expected to follow.
Thousands of Flights Hit by Outage
The breakdown caused widespread disruption across Britain’s aviation network, with 2,145 flights affected across Tuesday and Wednesday.
Around 2,000 flights were cancelled during the wider disruption, leaving hundreds of thousands of travellers facing delays and changes to their journeys.
Airports including Heathrow, Gatwick, Luton and Stansted subsequently reported that operations had returned to normal by Thursday.
The latest incident has nevertheless intensified scrutiny of NATS and its leadership.
Calls Grow for NATS Chief to Resign
NATS chief executive Martin Rolfe has faced mounting pressure since the failure, with Ryanair boss Michael O’Leary describing his position as “untenable”.
Wizz Air has also called for Mr Rolfe to leave, saying it was “extremely disappointed” by the technical failure and arguing that NATS is “simply not fit for purpose in its current form”.
Mr Rolfe was summoned to a meeting with Transport Secretary Heidi Alexander last Wednesday and was given a week to establish the cause of the fault.
Ms Alexander has ordered that the report be on her desk by Wednesday.
She has so far stopped short of publicly demanding Mr Rolfe’s resignation, while also declining to give him an explicit vote of confidence.
Government Orders Independent Review
The Transport Secretary has also asked Civil Aviation Authority chief executive Rob Bishton to conduct an independent review, with the review expected to be completed within six months.
Ms Alexander told MPs that she did not believe the latest air traffic control disruption was necessarily unavoidable.
The scrutiny comes against the backdrop of previous NATS failures, including a radar-related problem last July that disrupted thousands of passengers and led to more than 160 flight cancellations.
In August 2023, more than 700,000 passengers were affected when NATS experienced another technical failure while processing a flight plan, resulting in widespread grounding of aircraft.
Questions Over Executive Payments
The pressure on Mr Rolfe has also been fuelled by his remuneration.
He has received £2.2 million in bonuses and incentive payments over the past three years, despite the organisation experiencing two major air traffic control failures in 2023 and 2025.
The latest breakdown has therefore renewed questions about the resilience of the systems operated by NATS and the accountability of its senior leadership.
Labour Faces Political Backlash
The incident has also created an awkward moment for the Labour government after it emerged that its aviation minister had praised improvements to the air traffic control system just one day before the latest failure.
In a written parliamentary response last Monday, Keir Mather said the system was “well prepared”, referring to measures introduced by ministers following the major malfunction in 2023.
The comments drew criticism from Conservative MP Richard Holden, who accused Labour ministers of trying to claim credit when the system was functioning while avoiding responsibility when it failed.
“Labour ministers can’t have it both ways: if they boast about systems they created when they’re working, they should take responsibility when they fail,” Mr Holden said.
Compensation Position Remains Unclear
Passengers affected by the disruption are also facing restrictions on compensation claims.
The Civil Aviation Authority has said travellers are unlikely to qualify for compensation where delays or cancellations were directly caused by the incident, because the failure is likely to be regarded as an “extraordinary circumstance”.
NATS, which operates the UK’s air traffic control services from its headquarters in Swanwick, Hampshire, remains at the centre of the investigation as officials work to establish precisely what caused the system to fail.
The organisation operates as a public-private partnership, with the UK Government holding the controlling stake.
The remaining ownership is divided among UK airlines including British Airways, easyJet and Virgin Atlantic, Heathrow Airport and NATS employees.
