Whiteboards and telephones to track the schedules of aircraft were part of contingency plans to back up Chek Lap Kok's sophisticated computer system, the inquiry was told yesterday. The plans were made after contractors encountered hundreds of bugs while developing the new flight information display system which allocates aircraft to bays, gates and check-in desks and runs monitors. Airport Authority chief executive Hank Townsend detailed its efforts to keep contractor GEC and subcontractor Electronic Data Systems to delivery deadlines. The system failed on the airport's first day and froze monitors carrying flight information or loaded them with old data. Controllers were prevented from assigning aircraft to vacant parking bays and information to airlines and other users was delayed. Dr Townsend said the system had operated successfully in three trials and an integrated test was conducted using data from Kai Tak for a fortnight before opening day. He said the contractors' difficulties included problems in writing software and matching the authority's technical specifications. The project, which started in mid-1995, did not meet the original completion date of December last year. The authority had prepared back-up and contingency plans in case the system could not be delivered in time and all electronic systems failed. These included another stand-by system as well as the whiteboard and telephone system which could display flight information for passengers, airlines and controllers, said Dr Townsend.