Director's vocabulary on flight information system proved unreliable

An Airport Authority executive admitted yesterday he had not known the difference between two crucial words used to describe Chek Lap Kok's flight information system.

Project director Douglas Oakervee said on Thursday that incorrect information about the system, which broke down on airport opening day, had been submitted to the Airport Development Steering Committee.

The report said the system's 'reliability' was 98.7 per cent whereas it should have said its 'availability' was 98.7 per cent. 'Availability' is measured by simply testing the frequency that the system works over a number of trial runs. 'Reliability' takes into account factors such as how long the system runs at a satisfactory level.

Continuing his testimony at the Legco inquiry yesterday, Mr Oakervee said he had not thought there was any difference between the two words. 'I thought the two words were interchangeable,' he said. 'We did not intend to mislead anyone.' Mr Oakervee, an engineer for more than 40 years, was not aware of the difference until Airport Authority chairman Wong Po-yan was questioned about the system at the hearing last month.

A New Airport Projects Co-ordination Office report had also said the reliability level was more than 95 per cent. It was signed by Mr Oakervee as it was prepared by his engineers.

'I believed I was presented the truth. However, it was still possible that it was referring to the availability level.' Legislators wanted to know what he had done to make sure the system worked.