A week on from last Sunday’s fatal plane crash north of Athens, investigators took another small step toward understanding what caused the accident as the chief coroner confirmed yesterday that all the passengers and crew on board the Helios Airways flight from Larnaca had died on impact. Phillipos Koutsaftis said that autopsies on all 118 bodies recovered so far from the crash site in Grammatiko had proved that everybody on board was alive when the plane crashed. Three bodies remain unaccounted for and it is not yet known if those on board were conscious at the time of impact. Toxicological reports on six of those on board, including the co-pilot, revealed that they had not inhaled any carbon monoxide. However, the outcome of tests for other toxic gasses is expected in the next few days. The results should help investigators in understanding what seems to have knocked out the pilot and co-pilot and possibly many more on board. A theory gathering support in recent days is that a fault with the plane’s air conditioning system led to a gradual decompression of the cabin that incapacitated most of those on board because of a lack of oxygen. Shortly after takeoff from Cyprus, the aircraft’s German pilot reported a problem with the equipment cooling system and was in the process of trying to solve it with the help of Helios mechanics when all communication with the plane was cut off. The captain was later reported to be missing from his seat and the co-pilot slumped over the controls. It is thought that a gradual decompression may have caught the two men unaware as they tried to solve the initial problem. Koutsaftis told Agence France-Presse that traces of blood from steward Andreas Prodromou were found in the cockpit, thereby reinforcing the theory that the 25-year-old, who was trained to fly small aircraft, tried to land the plane. The plane experienced a decompression problem last December during a flight from Warsaw to Larnaca. Sources at the Cypriot Civil Aviation Authority told Sunday’s Kathimerini that they grounded the plane after the flight until the problem was fixed. Engineers could not find anything wrong with the Boeing 737-300 so it was flown to the UK for experts to examine it. They also found no fault but replaced some key components with new ones as a precautionary measure, sources said.