Airport officials should have known in January that flight data systems would not be ready to start operations on the July 6 opening day, it was claimed yesterday. Experts appointed by the Commission of Inquiry on the New Airport said the development of the flight information display system (FIDS) had by January still not met an important milestone set for November last year. Professor Vincent Shen of the University of Science and Technology's computer science department said the Airport Authority should have known at the time of the delay that about two months' work on the system would be needed after the targeted opening date. But Simon Westbrook SC, for Electronic Data Systems, argued that in early January the targeted opening date was still April. He said the announcement later that month to defer the opening to July allowed for an extra 10 weeks' work. Professor Shen and Dr Ulrich Kipper of Frankfurt Airport said additional slippage to work schedules after April meant the extra months were still needed despite the deferral. 'Despite the sudden relief of 10 weeks, I feel January was the right time to consider that FIDS may not be ready for July,' Professor Shen said. 'January would have been a good time . . . six months of testing is quite consistent with industry standards. [The milestone delay] should have been a big sign.' Witnesses have told the commission problems with the flight data system confused passengers, ground crews and airlines, contributing to the chaos of opening day. The inquiry before Mr Justice Woo Kwok-hing continues today.