The world's airlines are expected to post a profit of 8.9 billion dollars this year, in a sharp upgrade of previous forecast. The International Air Transport Association (Iata) said the industry recovery had been stronger and faster than anyone predicted. In June, it had predicted a much smaller profit of 2.5 billion dollars. In March, it had expected a loss of 2.8 billion dollars. Iata said increasing demand and stable costs were driving the recovery.However, Iata chief executive Giovanni Bisignani warned that there was still uncertainty surrounding the strength of the recovery. He said there are lingering doubts about how long this cyclical upturn will last.