Human error and the failings of Helios Airways, Cyprus’s regulatory authorities and US airplane manufacturer Boeing were to blame for an airline crash north of Athens last August which killed all 121 people on board the Cypriot plane, an investigation which was given to the Transport Ministry yesterday has found.

The probe was carried out by a Greek team of investigators headed by Akrivos Tsolakis and indicated that the two pilots, the German captain Hans Juergen Merten and his Cypriot co-pilot Pambos Charalambous, were mainly to blame.

They failed to notice during preflight checks that the plane’s pressurization system had been switched from automatic to manual. The pilots also misinterpreted a warning signal on the Boeing 737-300 which indicated that cabin pressure had dropped after the plane took off from Larnaca, headed for Prague.

In his last communication with the Helios flight center soon after takeoff, Merten said that a takeoff configuration warning signal had sounded and he also reported a problem with the equipment cooling systems.

The pilots were rendered unconscious from a loss of oxygen and the plane flew on autopilot for two hours until it ran out of fuel. A cabin attendant somehow managed to remain conscious and was seen grappling with controls shortly before the plane crashed into a hillside in Grammatiko.

However, the report also criticized the poor management and approach to flight safety at Helios as well as regulatory authorities in Cyprus for not overseeing safety adequately. Helios has since been renamed Ajet.

The investigation team also accused Boeing of failing to respond to similar incidents in other 737-300s. The report said the “ineffectiveness of measures taken by the manufacturer in response to previous pressurization incidents in that particular aircraft” had been an indirect cause of the crash. Boeing said that it would take “whatever actions are necessary” to maintain the safety of its fleet.

The report was also given to Cypriot authorities yesterday.