UK flights disrupted as NATS suffers another major technical failure

The UK’s main air traffic control body, NATS, has suffered another major technical fault in less than two weeks.

The fault occurred at NATS’ Prestwick centre and affected its Flight Data Processing System. The issue meant controllers had to reduce the number of aircraft entering the airspace to maintain safety.

“Early this morning (Monday 21 September), we experienced a technical issue at our Prestwick centre in Scotland,” NATS said. “To maintain safety, air traffic restrictions were applied to manage traffic demand while our engineers investigated.”

NATS says that the issue has now been fixed and that it is working with airlines and airports to reinstate smooth running of the UK’s air traffic.

Which airlines and airports are being affected by the NATS issue?

According to data from Cirium, an aviation analytics company, the impact so far has been manageable, but is expected to worsen as the day goes on. Cirium said that just 1.15% of departures have been cancelled or severely delayed, alongside 1.21% of arrivals. A ‘normal’ level of cancellations would be around 1-2% by the end of the day, but it’s still early on Monday in the UK.

“…as it’s early in the day, we anticipate that operational performance will degrade quickly,” Ciruim shared with AGN.

The immediate disruption is concentrated across:

• Scotland, particularly Edinburgh and Glasgow
• Northern Ireland, including Belfast
• Manchester and parts of northern England
• Some North Atlantic traffic using Prestwick-controlled airspace

Glasgow and Belfast are noted to have particularly high cancellation rates already, although the London-area airports are functioning normally so far.

easyJet is the most affected airline, with 29 (over 4%) of its services cancelled. Loganair has also suffered some cancellations, and British Airways, Ryanair and KLM are also experiencing disruption.

Is this the same NATS issue as before?

NATS has said categorically that today’s issue is not linked to the air traffic meltdown on 8 September, which affected London area airports and caused disruption for hundreds of thousands of passengers.

“This was a connectivity issue with part of our systems network, specific to the operation in Scotland. It is nothing to do with the problem we had earlier this month,” NATS shared.

The 8 September failure originated at Swanwick and affected the National Airspace System used to manage flight information across the UK. NATS traced that incident to a software defect triggered during a manual aircraft squawk code request. Corrupted data forced the system to be restarted, and restrictions remained in place for around six hours.

Today’s incident at Prestwick appears to involve a seperate flight data processing system, but that will be of little comfort to the passengers and airlines attempting to get underway.

For NATS, it couldn’t have come at a worse time. CEO Martin Rolfe has already been pulled up in front of the UK Government to explain the earlier September outage. In defence of the NATS operation, he said that this had been an isolated incident and that mitigation had been put in place. Now, he will face more scrutiny and a further explanation of what caused today’s chaos.

Unfortunately for Rolfe, today’s outage has spurred more calls for his resignation, particularly at Ryanair, which has been advocating for a change of leadership at NATS since the 2023 meltdown.

“Just three days after NATS assured airlines and passengers that it had introduced a robust ‘mitigation plans’, its flight data processing system has failed again. More than 25,000 Ryanair passengers have already suffered disruption, with over 140 Ryanair flights delayed, yet NATS still cannot tell passengers when this disruption will end,” said Ryanair’s Chief Operations Officer, Neal McMahon.

“Enough is enough. Martin Rolfe should resign today. If he will not, then Transport Secretary Heidi Alexander should fire him and appoint somebody capable of delivering the resilient ATC service that UK passengers and airlines deserve.”