The Cypriot airliner, which crashed earlier this month killing 121 people on board, had lost cabin pressure and ran out of fuel before slamming into a mountainous region near Athens, according to a preliminary report released on Monday.
Cypriot plane crashes in Greece
Chief investigator Akrivos Tsolakis presented the findings to the transport ministry following the analysis of flight recorders and autopsies on 118 bodies recovered from the site. 3 bodies have not been found.
Helios Flight 522, flying from Larnaca, Cyprus to Athens, crashed near the village of Grammatiko, 40 kilometres north of Athens, in Greece's worst air disaster.
"There are indications of technical problems in the pressurisation system ... There is proof that the engines of the plane stopped working because the fuel supply was exhausted, and that this was the final cause of the crash," said the report, a copy of which was faxed to The Associated Press.
Dead found at air crash site near Athens
It also said that there were indications that the pilot and co-pilot of the Boeing 737-300 had been incapacitated and that a third man had attempted to steer the plane. This man is believed to be flight attendant Andreas Prodromou, whose blood was reportedly found in the remains of the cockpit. He had received flight training in the past.
According to the report, the man in the cockpit tried to issue a Mayday distress call, but his communications had apparently been set to the wrong frequency.
"There are indications that, ... a man was sitting in the (pilot's) seat, wearing an oxygen mask," it said, adding, "the tone of his voice suggested the person was a man who was suffering or was exhausted."
The preliminary findings were announced after a former chief mechanic at Helios said the plane lost cabin pressure during a December flight after a door apparently was not sealed properly.
On the day of the crash, two Greek air force F-16 aircraft were scrambled to intercept the flight shortly before the accident. They reported seeing the co-pilot slumped over the controls, apparently unconscious, and said the pilot was not in his seat.
They also reported seeing oxygen masks dangling in the plane's passenger cabin. On Sunday, Public Order Minister Giorgos Voulgarakis repeated government assurances that the plane had not been shot down.
"If this incident had taken place during the Olympics, the chances of it being shot down would have been extremely high," Voulgarakis said in a newspaper interview.