PRESTWICK, UNITED KINGDOM — A network connectivity fault at NATS’ Prestwick air traffic control centre disrupted flights across northern parts of the UK on Monday, 21 September. Engineers fixed the issue, but airlines warned that cancellations and delays could continue as restrictions were lifted.
The failure affected air traffic management in Scotland, with knock-on disruption across Northern Ireland and northern England. Airports including Glasgow, Edinburgh, Belfast and Manchester reported affected services, while airlines worked to accommodate passengers whose journeys had been delayed or cancelled.
National Air Traffic Services (NATS) confirmed that the fault had been resolved and said it was coordinating with airports and airlines to restore normal traffic levels safely.
However, the restoration of the affected system did not mean that every scheduled flight could depart immediately. Passengers were advised to check their individual flight status directly with their airline.
A Scottish network fault forced NATS to restrict air traffic
NATS identified the cause as a connectivity problem involving part of its systems network used for operations in Scotland.
The company said the technical issue developed early on Monday morning. Air traffic restrictions were introduced while engineers investigated, limiting the amount of traffic being handled.
Such restrictions allow controllers to manage demand within the capacity available during a technical problem. Their purpose is to maintain safe operations rather than continue handling the normal volume of aircraft with reduced system capability.
In its official statement, NATS confirmed that the underlying technical problem had been fixed. It said the remaining restrictions were being withdrawn in coordination with airlines and airports.
The statement did not identify the precise network component involved, establish why the connection failed or specify when every restriction would be removed.
Those details remain important in distinguishing the immediate restoration of the service from a complete explanation of the failure.
Edinburgh, Glasgow, Belfast and Manchester flights affected
The disruption was concentrated on flights using northern UK airspace, although its effects extended beyond the airports closest to Prestwick.
NATS said earlier in the day that airports south of Manchester were broadly unaffected, while flights travelling north and services departing Scottish airports were experiencing delays.
Manchester, Edinburgh and Belfast were among the airports reporting disruption. Highlands and Islands Airports Limited also warned that schedules across its airports were affected, including services involving Inverness, Dundee and Islay.
Airlines including easyJet, Ryanair and British Airways reported disruption to their operations.
The Associated Press reported that aviation data company Cirium had recorded at least 200 cancellations involving flights departing from or arriving in the UK during Monday's disruption.
That figure was an interim industry count, not a final NATS assessment. The number of affected flights could change as airlines adjusted schedules.
Ryanair separately said it expected more than 25,000 of its passengers to be affected. That was the airline's own estimate, rather than an independently established total for all carriers.
A disruption centred on one air traffic control facility can affect journeys elsewhere in an airline's network. Aircraft arriving late may be unavailable for subsequent departures, while crew schedules, connections and airport turnaround arrangements can also be affected.
Consequently, even airports outside the area subject to the original restrictions may experience individual delays.
System restored, but flight schedules require separate recovery
Monday's developments involved two distinct stages: fixing the network problem and restoring the airline schedules disrupted while restrictions were in place.
NATS confirmed the first stage had been completed. The second depended on how quickly air traffic capacity could be restored and how individual airlines managed their affected flights.
A flight already cancelled would not automatically be reinstated because the technical system was working again. Similarly, passengers booked on delayed services still needed confirmation of their revised departure times.
The distinction matters particularly for travellers with connecting flights, time-sensitive appointments or onward transport reservations.
Passengers should use their airline's flight tracker, app or direct notifications to establish whether their service is operating. Airport departure boards can provide additional information, but NATS specifically directed passengers to their carriers for the latest flight-specific advice.
Travellers whose flights are cancelled should also establish their available rebooking or refund options before purchasing replacement tickets independently.
Passengers retain care and rebooking rights during disruption
Under UK passenger rights rules, airlines have obligations to affected travellers even when disruption originates outside the airline itself.
The UK Civil Aviation Authority (CAA) says passengers whose flights are cancelled and covered by UK law must be offered a choice between a refund and alternative transport to their destination.
The airline must also provide appropriate care while passengers wait for replacement travel. Depending on the circumstances, that can include food, refreshments, communications, overnight accommodation and transport between the airport and accommodation.
Passengers experiencing qualifying delays also have care entitlements. The relevant waiting period depends on flight distance, beginning at two hours for flights shorter than 1,500 kilometres.
If an airline cannot arrange reasonable care directly, affected passengers should retain itemised receipts for necessary expenses they intend to reclaim.
These care obligations are separate from entitlement to fixed financial compensation.
Compensation may not be payable when an airline demonstrates that a cancellation or long delay resulted from extraordinary circumstances that could not have been avoided despite reasonable measures.
The CAA indicated that the separate NATS failure on 8 September was likely to fall within that category. That statement should not automatically be treated as a definitive ruling on every claim arising from Monday's incident.
Passengers should submit claims to their airline and assess the response against the circumstances of their individual journey.
Prestwick incident follows separate UK system failure on 8 September
Monday's disruption occurred 13 days after an air traffic control failure on 8 September that caused more than 2,000 flight cancellations and affected hundreds of thousands of passengers.
NATS has explicitly stated that the two incidents were unrelated.
The earlier failure involved a software defect in the National Airspace System, which supports flight data management across UK airspace.
According to a preliminary NATS report published on 18 September, the defect affected the processing of an aircraft identification code request. Subsequent flight data updates were also affected, reducing the information available to controllers.
Restrictions during that incident lasted approximately six hours. NATS said the resulting passenger disruption took more than two days to clear.
Monday's fault, by contrast, was described as a network connectivity problem specific to the Scottish operation.
The distinction does not establish whether the incidents share any broader organisational or resilience-related factors. NATS has not published a detailed technical account of Monday's failure establishing such a connection.
The repetition of major disruption nevertheless prompted renewed criticism from airlines.
EasyJet questioned the resilience of NATS' systems, while British Airways expressed disappointment at another technical fault affecting customers.
Ryanair called for NATS chief executive Martin Rolfe to step down. The demand is the airline's position, not a conclusion established by a technical investigation.
Transport Secretary Heidi Alexander acknowledged the disruption and said systems were resuming following the repair.
The CAA had already been asked to conduct an independent review of the 8 September incident, while NATS said a full report on that failure would follow its preliminary findings.
For the latest Prestwick incident, the immediate technical problem has been resolved. The final number of affected flights, the time needed to restore normal schedules and the detailed cause of the network failure remain subjects for further reporting.
Until airlines confirm their individual services, passengers should not assume that the restoration of the air traffic control system means their travel plans are unaffected.