Nats confirmed it experienced a "technical issue" at its Prestwick control centre in Scotland on Monday morning (21 September), which required air traffic regulations to manage traffic as it was investigated.
The issue has since been fixed, with Nats stressing it was working with airports and airlines to lift the air traffic restrictions. It comes days after Nats issued its preliminary report into a major ATC outage earlier this month, which affected in excess of 2,000 flights, after Chief Executive Martin Rolfe was told by Transport Secretary Heidi Alexander to publish its initial findings within a week.
"This was a connectivity issue with part of our systems network, specific to the operation in Scotland," said Nats. "It is nothing to do with the problem we had earlier this month.
"We apologise to passengers for the disruption and thank them for their patience. Passengers should continue to check with their airline for the latest information on their flight."
Earlier, Nats said airports south of Manchester were "broadly unaffected" but warned flights "heading north and departing Scottish airports" were currently subject to delay.
Flights delays and cancellations were reported at Aberdeen, Glasgow, Edinburgh, Belfast International, Belfast City and City of Derry airports, as well as services to Scotland's Highlands airports.
There have been reports of delays and disruption too at Manchester, Newcastle, Liverpool, Bristol and London City airports.
Aviation analytics company Cirium confirmed 35 flights due to depart the UK on Monday have so far been cancelled or did not fly, and 37 arrivals. These figures do no necessarily relate to the Nats issue.
Nats' Resilience 'called into question' – again
Jet2 Chief Executive Steve Heapy said the repeat nature of the issues at Nats showed the need for "urgent and accountable action rather than reports and apologies".
“Once again, airlines and customers are being disrupted by yet another Nats issue, and one has to ask: how many more failures do customers and airlines have to deal with? This morning’s disruption comes days after Nats published a report into its latest major failure, and it is simply not good enough for this critical national infrastructure to keep letting customers down.
"Customers work hard to look forward to their holidays, and airlines work hard to deliver those holidays. They should not be repeatedly exposed to delays and disruption because the UK’s air traffic control systems cannot be relied upon.
"There have been too many incidents, too many reports and too many promises of lessons being learned. What customers and airlines need now is action, accountability and proper resilience, and we need it urgently."
An easyJet spokesperson said: "A Nats air traffic control system failure in its Prestwick centre is causing delays to flights with some unable to operate. This, once again, calls into question the resilience of Nats' systems and demonstrates the need for firm actions to prevent these repeated failures.
"We will do all we can minimise the impact of this for our customers and advise anyone due to fly today to check our flight tracker for the latest information.”
Tim Alderslade, Chief Executive of Airlines UK, added: "Yet another NATS failure is causing delays and disruption for passengers and airlines alike, and comes just days after its report into the most recent major outage.
"The UK's ATC system is critical national infrastructure and it must be resilient enough to keep people moving. Passengers and airlines deserve better and the independent CAA report, together with the forthcoming Civil Aviation Bill, must address the underlying weaknesses in the system so that these failures stop happening."
The Scottish Passenger Agents' Association said the incident raises yet more serious questions about the resilience of the UK's air traffic control infrastructure.
"For travel agents, it means another day of supporting customers, checking alternative arrangements and dealing with the knock-on effects of disruption which is entirely outside their control," said an SPAA spokesperson.
“Scottish passengers are particularly reliant on a resilient aviation network. Air connectivity is not a luxury for Scotland; it is fundamental to our economy, our tourism industry and our ability to connect with the rest of the UK and the world."
