A top-level safety report on the £623m National Air Traffic Services control centre at Swanwick, Hampshire, has revealed that technological problems contributed to a record number of overloads for air traffic controllers last year.
The report said that overloads more than doubled after the Swanwick En Route Centre went live in January 2002. "A number of problems and shortcomings associated with the technology used by the controllers were cited as creating an environment where overloads were more likely," said the Nats safety review committee report, which was commissioned by its board of directors.
By law, controllers must report an overload if their workload is excessive to the point where the safety of aircraft was, or could have been, compromised. The safety committee said there were 64 overloads last year, compared with 28 when en route aircraft were handled by the centre's predecessor at West Drayton near Heathrow.
The report acknowledged that Nats improved the clarity of its screens in November 2002, but said there were still problems. Controllers were concerned about screens being out of focus, the font size, the contrast of the text against the background and "garbling" of blocks of text.
Controllers also said the "technology available to them did not indicate imminent bunches in traffic". Their confidence in the efficacy of this type of technology was being "gradually eroded," said the report.
One controller quoted in the report said he was "shaking all the way home" after an overload. The report said that, at its most extreme, an overload could lead to a controller "losing the plot", but that managers did not consider the overloads to have compromised safety.
"There was a definite gulf in perception between controllers and managers about the extent to which overloads are taken seriously. This requires attention," said the committee of independent safety and IT experts, which was chaired by Bill Semple, former chief executive of Nats.
The report, which was published on the company's intranet in April, cited technology as one of three major issues causing concern among controllers.
Despite the technology problems, the report said Nats' performance on safety was better last year than at any time since records were first compiled in their present form.
Interviewed on BBC radio in January, Nats chief executive Richard Everitt, said, "Technically, Swanwick has been very successful; these are not my words, these are the words of our independent safety regulator."
The committee suggested that poor internal communication was due in part to concerns about leaked information to the media.
"A mature organisation should be able to discuss issues openly without undue concern for possible public relations consequences. Nats is a high-profile organisation, but it has to be prepared to be open about [overload reports] and similar subjects. A reputation for openness and honesty is a sign of a confident organisation able to tackle the challenges ahead."
Nats said it was addressing the problems revealed in the report.