The airfield lighting system at Chek Lap Kok had failed five times to respond to signals from the control tower, it was revealed yesterday. Problems with the $300 million system meant the opening of the second runway would have to be delayed by eight months, the Airport Authority said in a submission to Legco's economic services panel. It had been reported that the opening of the second runway would have to be put back to next June. Since the airport opened last July, there had been five occasions when the airfield ground lighting system failed to respond to commands from air traffic controllers as quickly as it should, the submission stated. Details on the delays were not available from the authority. The lighting system comprises circuits linking lights on the airfield with control stations known as vaults, which are connected to the control tower via a fixed communication network. Checks revealed there were problems with this network, which also carries signals from other computerised systems. In all cases, the system was switched to manual control from the vaults. 'At no time was safety compromised, or air traffic affected,' said Billy Lam Chung-lun, the authority's Acting Chief Executive Officer. Having learned from the airport's chaotic opening, the authority and the Civil Aviation Department considered it sensible to make improvements to the second runway before it opened to provide other means of control from the control tower. These would involve placing the formal functions of the lighting system on a dedicated communications system. In addition, a manual back-up control link between the control tower and the vaults would be installed. Meanwhile, improvements will be made to the first runway. Mr Lam said the second runway would be considered for emergency use if the first had to be closed. Secretary for Economic Services Stephen Ip Shu-kwan said the first runway would offer sufficient capacity for air traffic in coming months. It has a capacity of 37 movements an hour, compared to 31 at Kai Tak, but air traffic has dropped 20 per cent against forecasts due to the regional economic downturn.