Amid controversy over whether screens at the air traffic control centre at Swanwick are unclear and a risk to safety, the Civil Aviation Authority has watered down its rules for governing the computer displays.
MP Tom Brake, transport spokesman for the Liberal Democrats, said he is "astonished" that public servants at the CAA have removed a clause in their rules which specifically required that display screens at Swanwick met standards for clarity. These standards were provided for in the regulations of the Health and Safety Executive.
The CAA's "CAP 670" requirements for the approval of air traffic control systems have been amended and now exclude a clause about the displays. Previously the rules had said that display screens used by controllers "shall be designed to meet the relevant health and safety regulations for visual display units".
The clause was removed quietly, as the Health and Safety Executive investigated the owner of the Swanwick centre, National Air Traffic Services, over the clarity of the screens and other matters related to the use of computer equipment.
The CAA said the removal of the clause is "merely a tidying up of regulations" but its critics said it is breaking a promise made by the government that the partial privatisation of Nats would not lead to any watering down of safety regulations.
Brake said, "It is astonishing that, with the concerns that are being expressed about the legibility of visual display units at Swanwick, the CAA has deleted a reference to the need for displays to meet relevant health and safety regulations."
Last year some air traffic controllers warned Nats in internal safety reports, leaked to Computer Weekly, that they were misreading text and numbers on their screens. Although safety had not been compromised in these instances, controllers had made operational mistakes.
In December last year, as Brake pressed the authority for answers to questions about the screens, the CAA dropped the clause in its regulations.
In a letter to the CAA's chairman Roy McNulty on 28 October 2002, Brake had said, "I am writing with serious concerns about the risk to the health and safety of Nats employees and ultimately the implications for the flying public due to the alleged failure of Swanwick screen character sizes to comply with the appropriate regulations."
McNulty replied that the enforcement of regulations over the screens "is the responsibility of the Health and Safety Executive". If the executive considers that non-compliance might pose a risk to flight safety, it will raise the matter with the authority, he added. "This occurred in the case of the Swanwick display screens."
However, McNulty said the screens posed "no safety-significant risk to aviation" and so the matter was one between Nats and the Health and Safety Executive.
A few days later, in November 2002, Nats installed new software, which improved the displays. But this did not end the controversy. Swanwick's health and safety representative issued a notice that the screen displays still failed to meet standards for screen displays.
On 11 December last year the Health and Safety Executive wrote to Brake saying that it had no responsibility for the safety of the equipment, only the health and safety of the employees working at Swanwick. "Any risks to the safety of the aircraft controlled by the centre are matters for the Civil Aviation Authority," it said.
However, the executive said it had asked Nats to produce a "plan of action to reduce the risks to the health of their air control staff from display screen equipment".
One specialist in air traffic control said the CAA had watered down its regulations by removing the clause. "The CAA has a clear legal duty to ensure that air traffic equipment is fit for its intended purpose. Compliance with health and safety regulations was an important feature of this. The CAA is now shying away from its legal duty by removing that clause." he said.
"As there was doubt over whether the screens complied with legislation, this was the best possible time - from the CAA's point of view - to wash its hands of the matter by changing its rules so that it need no longer be involved as a regulator."
Arguably, the rule change has made it less onerous for the CAA to grant approvals for air traffic control systems. Its officials said the clarity of screens is an ergonomic issue, relevant only to the health and comfort of controllers, and this is a matter for the Health and Safety Executive, not the CAA. But ergonomic specialists say safety is intertwined with the comfort and health of air traffic controllers.
A spokesman for the CAA insisted that the removal of the clause in its regulations was nothing more than a "tidying-up" process. He said Nats must, like other employers, comply with rules on health and safety, so it is an unnecessary duplication to include it as a stipulation in aviation safety requirements.
But some industry experts believe the CAA should not have removed the clause. They point out that nobody is now regulating specifically the effect on safety of the display screens: the Health and Safety Executive says safety is not its concern, and the CAA says it is not responsible for enforcing regulations over the clarity of screens.
Brake said, "The CAA has left a grey area where it is unclear who has responsibility for safety in terms of the screens."