A MENTALLY ill man who attempted to hijack a Chinese airliner to Taiwan using fruit knives has been sentenced to four years in prison, State media and a court official said yesterday.Former firefighter Pan Huaxing suffered a “slight mental aberration’’ at the time of his May 10 hijacking attempt, said a spokesman for the Huli District Court in the southeastern city of Xiamen. That condition and the limited harm caused by the attempt won him a reduced sentence following the trial Friday, said the spokesman.Others who have attempted to hijack Chinese passenger planes have been sentenced to up to 15 years in prison.Xinhua News Agency said Pan boarded a flight from Shenzhen to Xiamen with a pair of knives stuffed in his socks. After takeoff, he rushed toward the cockpit and pressed one of the knives against a stewardess’ chest. Pan demanded the flight be diverted to Taiwan, about 160 kilometers away across the Taiwan Straits.Another flight attendant and passengers overpowered Pan and seized the knives, Xinhua said.China has further boosted airport security since the Sept. 11, 2001 terrorist attacks on the United States with more rigorous identification and luggage checks.(SD-Agencies)