UK flights disrupted by 'technical issue' with air traffic computer system

The UK's National Air Traffic Service (NATS) is spending a bank holiday Monday dealing with an unspecified "technical issue" that has disrupted flights across the country.

NATS said in a statement today that at 1210 UK time it "applied traffic flow restrictions to maintain safety." Half an hour later the an update was posted to clarify that UK airspace wasn't closed and the issue was still being investigated. 

Two hours into the outage, NATS posted an update to say that the issue was related to its ability to process flight plans, requiring officials to process each plan manually.

"Until our engineers have resolved this, flight plans are being input manually which means we cannot process them at the same volume, hence we have applied traffic flow restrictions," NATS said. "Our priority is ensuring every flight in the UK remains safe and doing everything we can to minimise the impact."

At 1515 the organization said that it had "identified and remedied" the technical issue and that normal operations were restarting, albeit under the careful watch of its engineers. Having to file flight plans by hand had caused significant delays but the body is working to clear the backlog.

Several UK airlines and airports have verified that there's an issue of some sort, with Scottish airline Loganair indicating the issue involved "a network-wide failure of UK air traffic control computer systems." 

"Although we are hopeful of being able to operate most intra-Scotland flights on the basis of local coordination and with a minimum of disruption, north-south and international flights may be subject to delays," Loganair said on X.

It's unclear if the issue is affecting Irish airspace under the control of the Irish Aviation Authority (IAA), which hasn't mentioned the outage. Dublin Airport, however, said the problem was affecting flights in and out of its facilities. 

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The issue is reminiscent of the US Federal Aviation Administration's Notice to Air Mission Systems (NOTAMS) outage that grounded flights around the US in January. The FAA later determined that the incident was caused by the accidental deletion of files essential to NOTAMS' operation.  

NOTAMS is responsible for notifying pilots of any last-minute alerts that may affect travel safety, and the outage grounded flights in the US from taking off, but not from landing if they were already in the air. Flightradar24, which tracks live flights around the world, said that it UK airports appeared to be "significantly limiting departures," but that arrivals were continuing. ®