AN investigation has been launched after part of a Chinese jumbo jet engine was ripped off as it scraped the runway during a landing in violent weather at Kai Tak. As Typhoon Sibyl lashed the territory, air traffic controllers went into overdrive with about 60 landings being aborted and more than 50 flights diverted to ports in Taiwan, China and the Philippines on Monday. Air China Boeing 747-400 flight CA101 from Beijing is believed to have been affected by sinking wind shear - a sudden downward burst of wind - as it attempted to land over Kowloon. Witnesses saw the jet lurch violently seconds before landing, hitting its outside left engine on the runway and tearing off part of the engine cowling. No one was reported hurt but engineers yesterday were examining the aircraft. Air traffic general manager James Hui Chee-sum said the Civil Aviation Department had requested that the aircraft's pilots provide a report on the incident. Officers from the department's Aerodrome Safety Division are handling preliminary investigations. 'They will decide what type of follow-up action is required but I don't see it as being a lengthy investigation,' Mr Hui said. East-northeast winds were gusting at an average 17 to 37 knots as the Air China jet approached Kai Tak at about 11 am on Monday. The executive vice-president of the International Federation of Air Traffic Control Associations, George Chao Pao-shu, said sinking wind shear and crosswinds probably contributed to the incident. 'In such conditions, airlines can get a sudden downward push from a wind surge which affects the descent profile. It can be dangerous,' he said. Air China representatives could not be contacted yesterday and it is not clear how many people were on board. One worker at Kai Tak described some of the landings and approaches on Monday as 'absolutely terrifying'. 'I've worked here on and off since 1974, but it's one of the worst days I've seen,' he said. The General Secretary of the Aircrew Officers' Association, John Findlay, said reports from pilots indicated the 24 hours before the typhoon passed Hong Kong had caused numerous problems for approaching flights. 'By all accounts, it was one hell of a night,' he said. Yesterday, as weather conditions improved, three flights had been diverted, 52 delayed and nine cancelled up until late afternoon. Wind shear is a common problem during strong winds at Kai Tak due to the surrounding hills forcing air down onto the runway. Decisions on whether to land are up to the discretion of the pilot, with most modern aircraft being designed to withstand typhoon-related weather conditions. In June last year, a Dragonair Airbus A320 damaged the runway during an emergency landing in severe weather after wing flaps jammed due to a fault with a warning system. The airliner finally landed at the third attempt but skidded off the runway onto a verge, injuring eight people. A report is due out soon into the crash of a China Airlines aircraft in November 1993 which skidded off the runway during a typhoon.