Workstation glitch forced UK airspace to knees

UK air traffic control NATS said yesterday’s severe disruption was caused by an unprecedented failure in the system regulating controller workstations at its Swanwick centre.

Passengers flying to and from London were faced with severe flight disruptions after the system failure at NATS area control centre at Swanwick. Although the airspace was not closed, flights were halted at some of the country’s major airports.

Airports in other parts of the country such as Birmingham and Manchester, in central and northern England, were unaffected by the technical problem although Heathrow, Gatwick, Stansted and Luton were severely affected.

NATS said in a statement: “Swanwick controller workstations provide a number of tools and services to the controller to enable them to safely control a high volume of air traffic. In normal operations the number of workstations in use versus in standby fluctuates with the demands of the traffic being controlled.”

“In this instance a transition between the two states caused a failure in the system which has not been seen before. The failure meant that the controllers were unable to access all of the data regarding individual flight plans which significantly increases their workload.”

“Our priority is to maintain a safe operation for the flying public; consequently when the failure occurred we immediately took steps to reduce the traffic into and out of the UK network.  The controllers had a full radar picture and full communications with all aircraft at all times during the incident and at no time was safety compromised in any way.”

An investigation is now underway to determine the root cause of yesterday’s severe disruption in UK airspace, although NATS yesterday admitted that it stemmed from a problem with its flight data processing system. Speaking on the BBC News Channel on Saturday NATS chief executive Richard Deakin said that a ‘delinquent’ line of code has been discovered in 4 million lines of code had been responsible.

“The challenge is that we have around 50 different systems at Swanwick and around four million lines of code. This particular glitch was buried in one of those four million lines of code,” he said adding that the business was spending an extra £575 million over the next five years to update its systems.

One expert tells Air Traffic Management: “This morning’s update seems to imply that the problem was in the en-route system NERC, not the NAS flight data processing system, but in the interface between the two, associated with bandboxing (combining) sectors in London area centre. The two systems probably somehow got out of sync. This explains why Prestwick was not affected.”

The incident has prompted the UK transport secretary Patrick McLoughlin to brand the disruption as’ unacceptable’. “I have asked NATS for a full explanation of the incident,” he said in a statement. “I also want to know what steps will be taken to prevent this happening again.”

Last December, a computer glitch similarly prevented controllers from switching from night to daytime operations at NATS’ area control centre at Swanwick, disrupting airport operations across the UK, including Heathrow, Gatwick, Stansted, Luton, Southampton, Birmingham, Cardiff and Glasgow.

NATS chief Richard Deakin admitted at the time: “We had never seen this technical issue in over 10 years of operation at Swanwick, during which time over 20 million flights have been safely handled, with a service level among the best in the world.”

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