Planes are to fly twice as close to each other in Hong Kong skies under new aviation rules - set to take effect in just over a year - that will increase airspace capacity.
But senior air-traffic controllers say their ranks will have to be bolstered to handle the increased traffic when the minimum vertical distance between planes is reduced from 606 metres to 303 metres from February 2002. Horizontal separation will remain at a minimum of three nautical miles (5,556 metres).
Aviation experts have warned that because planes will be closer, strict measures will be needed to prevent dangerous wake turbulence - huge, powerful spirals of air from the wings - that can destabilise a following plane and in extreme cases even cause it to roll without warning.
The Civil Aviation Department - which has been fighting a public relations battle after a series of near misses and 'mid-air incidents' that has seen five air-traffic controllers suspended from duty since August - has made no public announcement about the change.
However, a spokeswoman confirmed that Hong Kong was adopting the new international standards - known as Reduced Vertical Separation Minima (RVSM) - laid down by the International Civil Aviation Organisation (ICAO).
'Under this programme, aircraft operating in Hong Kong airspace between 29,000 feet and 41,000 feet will be separated vertically by 1,000 feet,' she said. 'The programme will enhance airspace capacity and increase the opportunities for aircraft to operate at optimum cruising levels.'