Flight Detent
Here's a copy of today's article in The Athens News. I think that it addresses your question. Information on the postion of outflow valve has not yet been released.
Helios puzzle 'recreated'
Questions about the strangest crash in aviation history multiply as Greek investigators re-enact the doomed flight which killed 121 people
By Dimitris Yannopoulos
AN UNPRECEDENTED "re-enactment" of the doomed Helios Airways flight that crashed 50km outside Athens on August 14 "has cast some light on the dark spots in the four-month probe", the Greek investigators said after the flying drill on the evening of December 19.
But 'experiments' carried out during the mock flight also raised more questions that needed further analysis, veteran captain Akrivos Tsolakis, chairman of the Air Accident Investigation and Aviation Safety Board (AAIASB) told reporters. "Some of our assumptions and flight recorder data were confirmed, but others need revision and further scrutiny," Tsolakis said.
All 121 people on board were killed when the Boeing 737-300 slammed into a hillside.
The plane apparently had lost cabin pressure after takeoff, incapacitating the pilots, and eventually crashed into a Grammatiko hillside as it ran out of fuel after flying pilotless for nearly three hours. Investigators carried out the re-enactment of Helios Flight 522 from Larnaca, Cyprus, to Athens to analyse the causes of Greece's worst air disaster and probably the weirdest accident in aviation history.
Flight attendant's heroism
The most striking new finding of the flight's recreation was that the flight attendant, Andreas Prodromou, was in control of the Cypriot Helios Airways plane in its final path, 15-20 minutes before it crashed. A trained pilot who was working as a steward with Helios until he could find a co-pilot's job, Prodromou - donning a cabin crew oxygen mask - tried to save the doomed flight and wrestled with the controls after entering the cockpit by punching in the door code while the plane was still doing its holding rounds at 34,000 feet over the island of Kea.
Tsolakis had earlier hypothesised that Prodromou entered the cockpit after the plane's left engine burned out. AAIASB executive director Serafeim Kamoutsis said they now believe that the 25-year-old Prodromou entered the cockpit before the engine failure while the plane was still in a holding pattern and the pilots were unconscious or partially conscious. "He tried to fly the plane manually as best as he could when the autopilot disengaged," Kamoutsis said, adding that it was too early to say how the auto-pilot was disabled.
Why not climb down
Tsolakis said he believed the Cypriot airliner suffered a "partial, and not total loss of pressure" at an early stage in the flight. At its highest "cruising" altitude of 34,000 feet, the plane's cabin altitude – the pressure inside the fuselage - had reached 26,000 feet when, under normal pressurisation, it should remain at 8,000 feet throughout the flight. "This (loss of pressure) occurred during the ascent, in the first five minutes after takeoff from Larnaca..." Tsolakis said. The flight attendant, with other members of the cabin crew, remained conscious, however, because they used the plane's portable supply of oxygen, he added.
Asked by the Athens News why they didn't stop the climb below 10,000 feet when the pressurisation problem was obvious but not yet fatal for the crew or passengers, Tsolakis admitted that this remains a mystery. "We are still investigating why the pilots continued their ascent and did not respond properly," Tsolakis said.
Kamoutsis admitted that at a cabin-altitude ascent rate of 2,500 feet per minute most passengers' eardrums would feel like bursting within seconds from takeoff. Normal ascent rate of a fully pressurised cabin is 300-400 feet per minute - anything above that rate can be painful. "We know that this makes the theory of the confusion of the decompression alarm signals with configuration problems difficult to swallow," Kamoutsis told the Athens News, referring to the initial speculation that, at 12,000 feet, the pilots mistook the decompression alarm signal for a takeoff warning that only sounds on the ground. "But we have no other rational explanation for their failure to climb down before they passed out," he said.
Investigators suspected that a mode selector switch for controlling the plane's two pressure valves had been placed on the wrong setting, but, following the re-enactment flight, Tsolakis cautioned that this fact alone was not enough to explain the accident. "The switch is not the main issue," he said, acknowledging that the position of the switch on "manual" instead of "auto" could not by itself produce such loss of pressure. "We have to look into the factors behind the position of the switch to determine why it was found in that position and what happened to the pressure valve after takeoff."