The CAA has removed a clause in its CAP 670 requirements for air traffic control systems which had said that the display screens used by controllers "shall be designed to meet the relevant Health and Safety Regulations for visual display units".
The removal of the clause comes amid a continuing controversy over whether screens at an air traffic centre at Swanwick, Hampshire, are unclear and a possible risk to the safety of aircraft.
Computer Weekly has learned that the Health and Safety Executive is continuing its investigation into whether the screens at Swanwick meet its regulations, even though the owner of Swanwick, National Air Traffic Services, installed new software in November last year which improved the clarity of the displays.
The Health and Safety Executive has no direct responsibility for flight safety, but where it considers that non-compliance with its screen regulations could pose a risk aircraft, it will raise the matter with the CAA. In a letter to Tom Brake, transport spokesman for the Liberal Democrats, Roy McNulty chairman of the CAA confirmed that the Health and Safety Executive had raised the issue of flight safety with the CAA.
However, McNulty said the screens posed "no safety significant risk to aviation" so it was a matter between Nats and the Health and Safety Executive.
Brake was surprised that the CAA had removed the clause. He said, "It is astonishing that, with the concerns 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."
The CAA said the removal of the clause was "merely a tidying up of regulations". But some controllers believe that the CAA is breaking a promise given by the government that the partial privatisation of Nats would not lead to any watering down of safety regulations.
Assuring MPs that the high standards of safety and regulation would be maintained after the part privatisation a government statement in March 2001 said, "There can be no question of those standards being watered down."
Last year some controllers warned Nats in internal reports leaked to Computer Weekly that they were misreading text and numbers on their screens.