<span style="color: #222222;">Iranian authorities today said that the Ukrainian airliner, which crashed shortly after takeoff from Tehran with the loss of all 176 people on board, had turned back after experiencing a problem. </span><br />'' <br />'' <span style="color: #222222;">Iranian Civil Aviation Organisation has said on its website that the plane, which was initially headed west to leave the airport zone, turned right following a problem and was headed back to the airport at the moment of the crash. It said the plane disappeared from radar screens the moment it reached 8,000 feet. </span><br />'' <br />'' <span style="color: #222222;">The pilot sent no radio message about the unusual circumstances. The organisation added that eyewitnesses have said, a fire was seen on board the plane which grew in intensity. The organisation said it has questioned witnesses both on the ground and on board a second aircraft which was flying above the Ukrainian Boeing 737 as the disaster unfolded.</span><br />