THE Civil Aviation Department should have consulted the residents and district boards in North Kowloon before scrapping the ''opposite runway' mode of operation at the Kai Tak Airport, legislator Frederick Fung Kin-kee said yesterday. The Civil Aviation Department (CAD) suspended the ''opposite runway'' air traffic system on October 30 for safety reasons. Under the new system, planes will fly over North Kowloon every night, whereas previously this occurred only 40 per cent of the timewhen made necessary by wind conditions. After meeting CAD officials, Mr Fung said more than 20 extra aircraft would now fly over the populated residential areas in North Kowloon every night after 9 pm and early every morning. Mr Fung, who is a member of the Hong Kong Association for Democracy and People's Livelihood, said the Environmental Protection Department standards stated that any sound louder than 70 decibels would be considered noise in the evening. The 250,000 residents in North Kowloon had to put up with noise as loud as 100 decibels more than 20 times a night. He was also worried that the scrapping of the ''opposite runway'' mode would become an excuse for the CAD to increase air traffic in the evening, which would be even more of a noise nuisance for North Kowloon residents. However, the CAD's air traffic general manager, James Hui Chee-sum, said the department would not increase aircraft movements at Kai Tak after the scrapping of the ''opposite runway'' mode. Mr Hui declined to guarantee that the department would firmly refuse demands from other government departments or airlines to increase air traffic. ''That'll be another question if somebody asks us to increase aircraft movements if that would be beneficial to the economy of Hong Kong,'' he said.