Air traffic control system is 'not safe', say UK controllers

Summary:Prestwick, one of two major air traffic control hubs in the UK, is in the process of implementing new flight data technology that controllers have said is 'not fit for purpose'

Technology being introduced at one of the two major UK air traffic control hubs is "not fit for purpose" and did not adequately handle a breakdown in air traffic communications, according to a number of air traffic controllers.

Glasgow Prestwick Airport

Technology being introduced at an air traffic control centre in Glasgow is "not fit for purpose", according to air traffic controllers.

The EFD (Electronic Flight Data) system rolled out at the Scottish and Oceanic Air Traffic Control (ATC) Centre at Glasgow Prestwick Airport has had difficulty handling complex inputs, according to people posting on an air traffic control forum.

"[Controllers] don't want to use this system, not because they like to have a whinge, but because they know it is neither safe, nor efficient enough to do the job," wrote one Prestwick controller, Arty-Ziff, on the Pprune forum in February. "This system should have been tested properly before it went into live operations."

Another, maintainhighspeed, said: "EFD is used in Nigeria, Israel and various towers. This system has experienced nothing as complex as the Prestwick Control Centre. It is struggling.

"I strongly feel that EFD is not capable of handling an Oceanic interface, ATSOCAS [Air Traffic Services Outside Controlled Airspace], procedural control, airways, single-man and double-man operation all in one," maintainhighspeed added.

[Controllers] don't want to use this system, not because they like to have a whinge, but because they know it is neither safe, nor efficient enough to do the job.

– Arty-Ziff, Pprune forum

EFD uses electronic flight data strips called smartStrips to log aircraft locations and commands, rather than the paper strips long used in ATC. The technology used at Prestwick runs on Java and Linux, and is being implemented by the National Air Traffic Service (NATS), the organisation in charge of UK ATC. The major human interface component is a Wacom tablet.

"My worry is that for a busy session, EFD will not be as quick or as robust as paper strips," wrote Pprune member anotherthing, who noted concerns that controllers might miss conflicts with electronic strips.

Real-time traffic

Theodor Zeh, director of human factors for Austria-based Frequentis, the provider of the technology, said the EFD system is capable of handling real-time air traffic at Prestwick. "The system can handle fast inputs," Zeh said on Monday.

However, he said that problems had been ironed out in live testing, which began at the end of January.

"The last big change to air traffic management was the introduction of radar 50 years ago. When change comes, it can be extremely painful and difficult. Any change will decrease the performance of a system by a certain amount of time," he told ZDNet UK.

Similar EFD systems have been implemented in Nigeria and New Zealand, Zeh added. The problems lie in air traffic controllers feeling comfortable with the interface, he said.

We fully understand where this comes from — air traffic controllers are really working in an extremely difficult environment — but change needs to be brought in.

– Theodor Zeh, Frequentis

"This is about how to implement functionality so controllers are fully confident, not [about] the capacity of the system," said Zeh. "We fully understand where this comes from — air traffic controllers are really working in an extremely difficult environment — but change needs to be brought in."

The EFD system is being phased in at Prestwick on a rolling basis. It is currently being used by controllers looking after West 2 LAG, the sector that covers Manchester in a 100-mile radius around the airport runway. The phasing-in began on 28 January, but has suffered problems, including latency and screens not working, according to forum posts.

"All we want is to go to work and not put two [planes] together. For the meantime, EFD is only making that more likely," wrote one Pprune user on 11 February. "I just hope that one day we don't have to turn around and say 'we told you so'."

System failure

On 15 February, the IBM-based National Air Traffic Service system covering the UK stopped talking to EFD. Air traffic controllers at Prestwick scrambled to remedy the situation. Some people on days off had to go into work to try to move the traffic build-up, which caused numerous delays to flights.

"Situation has deteriorated in Prestwick Centre," said an alert email quoted on the Pprune forum. "Problems with the electronic flight data processing system have not been solved yet."

Zeh said that the situation on 15 February had not endangered air travellers and that back-up systems at Prestwick had worked. "There were several fall-back layers — there wasn't ever an unsafe situation," he said. "The performance only went down when there was a real failure of the link [between NAS and EFD]."

The National Air Traffic Service, which is in charge of implementing the EFD system at Prestwick, declined to comment on the adoption and performance of the new technology.

"We don't comment on internet chatroom rumours," said NATS spokesman Patrick Horwood. "EFD is progressing and will be implemented in full. The project team continues to work hard to ensure there is minimal impact to our customers while it is introduced."

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Topics: Security


Tom is a technology reporter for, writing about all manner of security and open-source issues.Tom had various jobs after leaving university, including working for a company that hired out computers as props for films and television, and a role turning the entire back catalogue of a publisher into e-books.Tom eventually found tha... Full Bio

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