Investigators probing the causes of the Helios airliner crash in August held a simulation of the flight yesterday in an effort to shed light on the accident that killed 121 people, according to sources. The four-hour simulation was held on Crete at the training facilities Olympic Airlines use for its pilots. There were no announcements made after the simulation. Sources said that the investigators used all the information they had to hand in order to reconstruct the conditions that prevailed during the Helios Airways flight that crashed 40 kilometers north of Athens, killing everyone on board. Meanwhile, a newspaper reported yesterday that the cockpit door of the Helios Airways plane was locked until a few minutes before it crashed. Citing chief investigator Akrivos Tsolakis, daily Ta Nea reported that a man who tried to steer the airliner was only able to enter the cockpit when the engines began running out of fuel, cutting power to the cockpit door and other parts of the plane.