The Cypriot airliner which crashed 10 days ago is likely to have lost pressure right after takeoff because a switch set to the wrong position had gone unnoticed, sources told Kathimerini yesterday. The Helios Airways Boeing 747-300 left Larnaca on the morning of Sunday August 14 but soon suffered decompression, according to the preliminary results of an investigation made public on Monday. However, sources indicated an incorrectly flipped switch may have caused the loss of pressure rather than some kind of malfunction. Engineers inspected the plane on the night of Saturday, August 13, after the cabin crew complained about a noise from the rear door. As part of their inspection, engineers carried out a compression test. This involved the switch for the plane’s compression system being turned to manual rather than automatic. It is thought that they did not switch the system back after concluding their tests. Sources said the captain and co-pilot may have missed this change during preflight checks before the plane left Larnaca. As a result, the plane would not have been pressurized on takeoff and would have lost oxygen as it climbed to its eventual cruising altitude of 34,000 feet. Investigators said Monday a lack of oxygen had rendered most people on board unconscious. The pilot reported a problem with his equipment cooling system shortly after takeoff but sources told Kathimerini that this may have been a symptom of the loss of cabin pressure. The German captain Hans Juergen Merten may have been concentrating on solving this problem and not realized the loss of pressure. Meanwhile, sources said the Greek Civil Aviation Authority is about to start performing more intensive checks on flights that touch down in Greece. Special teams will perform random checks on planes, regardless of whether Greece is their final destination or they are just stopping off. The government denied yesterday that it had rushed through a presidential decree tightening up safety checks on flights in Greece so it could be signed just days after the Helios crash. Government spokesman Theodoros Roussopoulos said the process had begun months earlier and the decree was passed to the President’s office on August 8.