Airlines have sharply criticised the UK's air traffic control system after a second technical problem in under a fortnight caused significant disruption to flights across the country. The incident on Monday, which affected services at airports in Scotland, Northern Ireland, and northern England, led to over 200 flights being delayed.

This latest outage raises further questions about the resilience of the National Air Traffic Services (Nats) system, which manages UK airspace. It follows a major software defect at Swanwick earlier in September that resulted in the cancellation of approximately 2,000 flights, impacting tens of thousands of passengers.

EasyJet stated that Monday's incident "once again calls into question the resilience of how the service works." Wizz Air expressed a "national confidence crisis" in Nats, with its UK managing director calling for urgent reform and questioning the leadership and board of directors. The airline industry's representative body, Airlines UK, declared that both passengers and airlines "deserve better service after yet another Nats failure."

Nats attributed Monday's disruption to a "connectivity issue," clarifying that it was unrelated to the earlier software problem. The connectivity issue has since been resolved, and Nats has stated it is operating at full capacity, though it warned of lingering knock-on effects. The organization has apologized for the disruption and is working with its customers to manage residual delays.

Preliminary data from aviation analytics firm Cirium indicated at least 117 departing and 110 arriving flights were cancelled. EasyJet was the most affected, cancelling 47 of its 670 scheduled departures. British Airways reported 12 cancellations from its 513 scheduled departures, calling the fault "disappointing."

The UK Civil Aviation Authority noted that passengers affected by the disruption are unlikely to be entitled to compensation. The authority stated that the technical issue would likely be classified as an "extraordinary circumstance" under passenger rights regulations, meaning that while airlines must look after passengers, compensation for delays or cancellations directly caused by the incident may not be applicable.

Jet2 CEO Steve Heapy called for "urgent and accountable action to bolster the UK's air traffic control infrastructure." Ryanair reiterated its demands for Nats chief Martin Rolfe to resign, asserting he had failed to deliver a reliable system or an effective backup. The airline reported that the outage affected 140 of its flights and approximately 25,000 passengers.

Experts have previously highlighted the complexity of air traffic control systems and the potential for cascading failures. The repeated technical issues at Nats underscore the critical need for robust infrastructure and contingency planning in air traffic management, particularly given the increasing volume of air traffic.