UK air traffic suffered significant disruption on Monday following an air-traffic control system outage that caused massive delays and cancellations on one of the busiest days this travel season.
The NATS national air-traffic service said it’s “currently experiencing a technical issue and have applied traffic flow restrictions to maintain safety,” according to a statement. “Engineers are working to find and the fix the fault.”
As a result of the failure, planners weren’t able to automatically process flight plans and were forced to revert to manual input, meaning they couldn’t manage the same volumes, NATS said in a separate release. Heathrow and Gatwick airports, London’s busiest airfields, both experienced hundreds of delays and dozens of cancellations.
While the UK air space hasn’t been closed outright, NATS said it has had to apply flow restrictions to maintain safety. Some international airlines were also affected, with Deutsche Lufthansa AG canceling flights from Frankfurt to Heathrow and Dutch carrier KLM circumnavigating the UK.
The glitch coincided with on one of the most active extended weekends, with the UK off on a national holiday on Monday and summer-vacation travelers returning home. Some 3,049 flights were due to depart UK airports on Monday, with about the same amount arriving, according to aviation analytics firm Cirium.
The failure occurred on a system that logs each aircraft’s flight plan, which allows controllers monitoring flights to know where planes are headed and other important data, according to a statement by NATS. The separate technology the company uses to track aircraft positions appeared to be functioning.
The issue had some similarities to a Jan. 11 outage in the US that prompted a halt to all departures for a brief period and led to about 10,000 delays. In that case, a Federal Aviation Administration computer that logged safety alerts covering such things as runway closures was shut down after contractors damaged an underlying database.
Swanwick Site
Eurocontrol, which regulates air traffic for the region, said the UK is experiencing “very high individual delays” because aircraft movements have been regulated at low rates.
NATS operates its systems from the Swanwick operations room about 100 kilometers (60 miles) southwest of London that manages the airspace over England and Wales up to the Scottish border, as well as lower-altitude traffic to and from London’s airports.
“Currently there is no indication of when a solution for the failure will be available so no improvements for flights entering UK airspace are foreseen in the near future,” Eurocontrol said.
With delays and cancellations piling up, returning to normal service can take several days because aircraft will be put out of position. Ryanair Holdings Plc said it will be forced to delay or cancel “a number of flights” to and from the UK on Monday.
Flight Refund
Data from Flightradar24 showed London Heathrow Airport had 70 canceled flights and 245 delays so far on Monday. Meanwhile, Gatwick Airport had about 236 delayed flights and 41 cancelations. Some planes were being held on the ground at both hubs, according to Flightradar24’s maps.
EasyJet Plc said affected customers can transfer their flight free of charge or receive a refund.
Logan air, the Glasgow-based Scottish airline, wrote in a post on X, formerly known as Twitter, that a “network-wide failure” of air traffic control computer systems in the UK may cause delays to its flights. British Airways said it’s working closely with NATS to understand the impact of the technical glitch.
Swanwick opened almost six years late in 2002 and at least 30% over budget after repeated software glitches. Since then, the UK has experienced several major system outages, including one in 2014 that forced NATS to restrict the number of flying aircraft.
--With assistance from Alan Levin.
(Updates with additional information on NATS workaround from second paragraph.)
