Helicopter hits enthusiast on head A model aircraft enthusiast suffered severe head injuries yesterday when a radio-controlled helicopter crashed into him. The accident occurred at about 1.50pm when Law Kwok-wah and friends were flying their craft in open space on Chun Wang Street at Tseung Kwan O Industrial Estate. A 6kg helicopter belonging to one of Mr Law's friends - a 1.5-metre long SST Eagle 3 WC worth about HK$30,000 with accessories - had just touched down with its rotor still spinning. It is suspected one of the controls was accidentally pressed when the friend handed the radio controls to Mr Law, and the helicopter suddenly moved forward, its spinning rotor slamming into Mr Law's head. Mr Law was taken to Queen Elizabeth Hospital, where he underwent surgery and was in critical condition. His friends said Mr Law, who works for a bus company, was an experienced operator of model aircraft and had been flying models for about 10 years. He had also taken part in open competitions but had not won any awards. Kenny Ma, chairman of the Hong Kong Radio Control Soaring Society, said he had known Mr Law for many years and he was an experienced model flyer. 'I have known him for some years. He has over five years of experience of flying both radio-controlled soaring planes and micro-radio-controlled helicopters,' he said. People new to flying model aircraft might have poor safety awareness, but Mr Law would not be one of them. Fans of model planes said they suspected the accident could have been caused by a disruption in radio frequency. 'Sometimes different people may unknowingly be tuned to the same frequency to control their craft,' one said. The accident occurred on a plot of unoccupied government land. The government has had a sign put up on the fence telling people not to fly model planes there, but trespassing is common. A spokeswoman for the Civil Aviation Department said the department would investigate the accident and follow up if necessary. 'Anyone who possesses a model aircraft which is heavier than 7kg is required to register with the department in order to fly [it],' she said. The department recommends four places for flying radio-controlled aircraft: San Wan in Yuen Long, Nai Chung and Clear Water Bay Road in Sai Kung and Tate's Cairn in Sha Tin. 'Model aircraft flyers are also reminded not to conduct the activity near the airport, as this could affect air traffic,' she said. Flying radio-controlled planes has become popular in Hong Kong in recent years.