The air traffic control outage that caused thousands of flights to be grounded across the UK earlier in the week was caused by a military aircraft entering “spurious” flight data into the system, according to a report.
Hundreds of thousands of passengers were affected after more than ۲,۰۰۰ flights were cancelled on Tuesday when the system used by the National Air Traffic Services (Nats) shut down for four hours.
According to the Financial Times, four people briefed on the incident claimed that the shutdown was caused by a flight plan submitted by a UK military aircraft, which caused a meltdown in air traffic control systems used by Nats which remained unfixed for several hours.
The paper also reported that Nats operations officer Kathryn Leahy called the operations managers of numerous airports and airlines, and “tensions boiled over” after Leahy informed them their flight processing system did not have a dedicated backup due to Nats being in the midst of a “complete overhaul of its systems” and because the amount of data it keeps meant duplicating it would cost “vast amounts”.
The crisis has put pressure on Martin Rolfe, the chief executive of Nats, who was summoned to a meeting by transport secretary Heidi Alexander on Wednesday.
Alexander, who said she did “not believe the issue was unavoidable”, was understood to have given Rolfe a week to report on the causes of the shutdown, while also commissioning an independent review by the Civil Aviation Authority (CAA) into the incident.
The outage is the most serious to affect British commercial airspace since August ۲۰۲۳, when a technical problem led to almost ۱,۶۰۰ flights being delayed. Nats came under fire after that episode, with the CAA setting out ۳۴ recommendations to improve its systems to avoid similar incidents, all of which were said to have been fully implemented.
Rolfe ruled out a cyber-attack, which was initially suspected, saying he “believes we’ve never seen an incident happen more than once, so this will be something different that we’ve never seen in ۵۰ years of operation”.
Numerous airlines have already called for Rolfe to resign or be fired over the outage. Ryanair’s chief executive, Michael O’Leary, accused Rolfe of “telling lies to save his own skin” and said his position was “untenable”.
O’Leary added: “We don’t need more investigations, we don’t need more reports and we don’t need another parliamentary committee hearing where Martin Rolfe will promise change, will promise resilience and will promise an effective backup system.”
The delays led to someaircraft full of passengers being stuck waiting for information for more than four hours, while flights due to arrive in the UK were diverted to different airports, with some forced to land in Germany.
Despite the far-reaching effect of the outage, it was understood that passengers affected were unlikely to be able to claim compensation, as delays were due to “extraordinary circumstances”.
The Ministry of Defence has said there was no wrongdoing on the part of the military.
A spokesperson from the MoD said: “We do not believe there’s any indication of an error on the part of the military. This is subject to the live Nats investigation, so it’d be inappropriate for us to comment further while that’s ongoing.”
