Second NATS outage disrupts flights across northern UK

Flights at airports across Scotland, Northern Ireland and northern England were disrupted on 21 September following a technical issue at NATS’ Prestwick control centre – the second significant air traffic control incident in less than two weeks.

image: NATS

NATS said the problem was a connectivity issue affecting part of its systems network at Prestwick. Air traffic restrictions were introduced to manage demand while engineers investigated the fault, with the issue fixed later that morning.

The disruption affected airports including Glasgow, Edinburgh, Aberdeen, Belfast International and Manchester, with airlines cancelling flights and warning of delays. Reuters reported that 24 flights had been cancelled during the initial disruption, while aviation analytics firm Cirium subsequently reported higher cancellation figures as the effects spread through the network.

NATS said the Prestwick incident was unrelated to the major failure at its Swanwick centre on 8 September. That earlier incident was traced to a software defect in part of the National Airspace System, which resulted in restrictions being applied across the UK and ultimately affected more than 2,000 flights.

The latest incident came just days after NATS published its preliminary report into the 8 September failure. The report said the earlier software defect had been identified and that a mitigation was in place while a permanent fix was safety tested and deployed.

The two incidents have renewed attention on the resilience of the UK's air traffic control infrastructure. Airlines UK said the Prestwick disruption demonstrated the need for the system to be sufficiently resilient to avoid repeated failures, while easyJet said the incident raised questions about the resilience of NATS systems.

The Civil Aviation Authority is separately conducting an independent review of the 8 September incident, following a request from Transport Secretary Heidi Alexander. The scope and findings of that review will therefore provide a further assessment of the resilience and performance of the UK's air traffic control systems.