The computer system of Pakistan International Airlines Friday broke down owing to the defective fiber optic link of the PTCL, after which Karachi Airport is cut off from other airports of the country. Talking to a private TV, the PIA spokesman Sultan Hasan said the computer system at the airports of Islamabad, Lahore, Peshawar and Multan is not working and PIA personnel are manually issuing reservation, tickets and boarding cards. Responding a question, the spokesman said manual system is fully in place for issuing the boarding cards to travelers and if the fiber optic link is soon restored, the PIA will not face more problems.