NICOSIA (AFP) – A real-time flight reconstruction of a doomed Cypriot airliner, which crashed near Athens in August, killing all 121 on board, will take place on December 19, Greek crash investigator Akrivos Tsolakis said yesterday. The flight will depart Cyprus’s Larnaca airport at the exact same time as the Helios Airways plane did on the morning of August 14. «Everything is ready and, God willing, it will take place on December 19,» Tsolakis told Cyprus state radio during a visit to the island. He said the same flight path and type of plane would be used – a Boeing 737-300 – in the hope of finding out exactly what led the aircraft to crash into a hillside outside Athens after flying on auto-pilot for three hours. «The Olympic Airways plane will be called Flight 121 in respect and remembrance for those who lost their lives,» said Tsolakis. A pressure valve left in manual mode is thought to be key to the cause of the crash. The pressurization valve on the Helios 737 had not been switched to automatic, resulting in the pressure equalization system not engaging in flight. It has long been suspected that the cabin pressurization system was mistakenly left in manual mode during a pre-flight check at Larnaca, resulting in the system not engaging during the flight to Prague via Athens. This made the cabin air thinner at the high altitude, causing those on board to lose consciousness and the most probable reason why the pilots were not in control of the plane. The pilots failed to notice the position of the switch before takeoff, according to previous press reports. Checking the switch is part of pilots’ pre-takeoff checklist. The flight reconstruction hopes to solve the mystery surrounding the air disaster, the worst suffered by either Cyprus or Greece. The vast majority of those on board were Cypriot families – many with young children – going on summer vacation.