Groups opposed to a third runway at Chek Lap Kok airport have urged aviation authorities to study a new method of spacing out incoming aircraft that would allow more landings at the existing runways on windy days. The South China Morning Post reported on Monday that Hong Kong could adopt a system called Time Based Separation (TBS), co-developed by the UK's National Air Traffic Services and based on wind speeds to cut delays and possibly allow additional flight movements. The system takes into account wind conditions as planes make their final approach and allows them to bunch closer rather than maintaining a constant distance. Strong headwinds cause delays and even cancellations because planes landing in the wind take longer to reach the runway even if they maintain a constant speed. The overall landing rate then drops. Michael Mo Kwang-tai, spokesman for the Airport Development Concern Network, said since Hong Kong positioned itself as a regional transit hub, delays in arrivals were bad news for passengers. "The transit time is sometimes tight, only 70 to 90 minutes. If the flight is delayed for 15 minutes, then you are doomed [to miss your connection]," he said, adding that the Civil Aviation Department should at the same time increase manpower and create additional landing paths. He said in the next few years more modern long-haul planes would be put into service, such as Boeing's 777x and the Airbus A350, and it would be difficult for airlines to expand their networks if there was no new capacity. Chek Lap Kok's handling capacity is expected to reach its maximum 68 flights per hour later this year. And the government said with a third runway, the handling capacity could be boosted to 102 flights per hour. Lam Chiu-ying, convenor of the People's Aviation Watch concern group, agreed there was no reason for the government to wait until the third runway was completed in 2023 to solve the saturation problem. "If you just wait, Hong Kong will only fall in the world rankings. You have got to have improvements every year," Lam said. "Otherwise Hong Kong will lose its competiveness - the thing that [officials] are concerned about." Lam, a former Observatory director, said Hong Kong was vulnerable to monsoons - large-scale wind systems - caused by differences in the temperature of land and sea over the seasons. In very exposed places, monsoon winds can exceed 70km/h. Andy Shand, NATS general manager in charge of customer affairs, told the Post that the company was gradually developing more functions on top of TBS, and one of them would be able to space aircraft according to its size in low-visibility conditions. He said their expectation was that over time the busier airports around the world would start using TBS. He added that by 2024, 17 major European airports are required to have the system installed. Shand also said airports had been quite positive towards the new system since it was presented in aviation conferences earlier in the year. The Civil Aviation Department has said it would continue to monitor air traffic growth and work closely with the Airport Authority and airlines to enhance the efficient use of the existing two-runway system.