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Helios Crash, News Item

Posted: Sat Sep 10, 2005 4:11 pm
by GAHorn
Sent to me by Rudy. Thought other's would want to read it.

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Following article is by Don Phillips, of the International Herald Tribune, on the sad story of the Helios accident. These two pilots completely missed the "Big Picture"!!!!!!!

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PARIS: The crew members of a Cypriot airliner that crashed Aug. 14 near Athens became confused by a series of alarms as the plane climbed, failing to recognize that the cabin was not pres- surizing until they grew mentally disoriented because of lack of oxygen and passed out, according to several people connected with the investigation.


Complicating the cockpit confusion, neither the German pilot nor the young, inexperienced Cypriot co-pilot could speak the same language fluently, and each had difficulty understanding how the other spoke English, the worldwide language of air traffic control.


A total of 121 people were killed in the crash after the plane climbed and flew on autopilot, circling near Athens as it was programmed to do until one engine stopped running because of a lack of fuel. The sudden imbalance of power, with only one engine operating, caused the autopilot to disengage and the plane to begin its final descent.


The Greek authorities have made cryptic statements hinting at oxygen problems but have so far not announced the full findings of investigators.


The people interviewed for this article agreed to do so on condition that they not be identified because none are official spokesmen for the investigation and because of political sensitivities arising from a Cypriot plane crashing in Greece.


Investigators pieced together the story of the crash from numerous sources. In the wreckage, they found the first solid clues--the pressurization valve and an air outflow valve set incorrectly. Air traffic control tapes provided infor- mation on the confusion in the cockpit. The plane had a sophisticated new flight data recorder that provided a wealth of information. There were maintenance records from the night before, and investigators interviewed the mechanics who worked on the plane.


Among other things, the investigators determined that the pilot was not in his seat because he was up trying to solve a problem that turned out to be not the greatest threat facing him.


The plane that crashed, a Boeing 737, underwent maintenance the night before. The maintenance crew apparently left a pressurization controller rotary knob out of place, according to the officials connected to the investigation, and the crew did not catch the mistake during preflight checks the next day. This meant that the plane could not pressurize.


At 10,000 feet, as designed, an alarm went off to warn the crew that the plane would not pressurize. However, the crew members mis- takenly thought that the alarm horn was a warning to tell them that their controls were not set properly for takeoff, the officials said. The same horn is used for both conditions, although the it will sound for takeoff configuration only while the plane is still on the ground.


The crew continued the climb on autopilot. At 14,000 feet, oxygen masks deployed as designed and a Master Caution light illuminated in the cockpit. Another alarm sounded at about the same time on an unrelated matter, warning that there was insufficient cooling air in the compartment housing avionics equipment.


The radio tapes showed that this created tremendous confusion in the cockpit. Normally an aircraft cabin is held at
8,000 feet pressure, so the crew at over 14,000 feet would already be experiencing some disorientation because of a lack of oxygen.

During this time, the German captain and the Cypriot co-pilot discovered they had no common language and that their English, while good enough for normal air traffic control purposes, was not good enough for complicated technical conversation in fixing the problem.

The crew members called the maintenance base in Cyprus and were told that the circuit breaker to turn off the loud new alarm was in a cabinet behind the captain. The captain got up from his seat to look for the circuit breaker, apparently ignoring the confused co-pilot.

As the plane continued to climb on autopilot, the air grew so thin that the crew became seriously impaired. The captain passed out first on the floor of the cockpit, followed by the co-pilot, who remained in his seat, according to the officials.

The autopilot did as it was programmed to do, flying the plane at
34,000 feet to Athens and entering a holding pattern. It remained in a long circling pattern, shadowed by Greek military jets, until fuel ran low and one engine quit.

Boeing, the maker of the plane, issued a notice shortly after the crash to airlines that it would revise flight crew training manuals to stress to crews that they must understand how the various warning systems work and what to do about them.

The notice stresses that the takeoff configuration warning horn will not sound under any circumstances after the plane has left the ground. The same horn will then be used only for a cabin altitude warning. The company notice said there had been other instances of confusion over the horn by pilots.

"Confusion between the cabin altitude warning horn and the takeoff configuration warning horn can be resolved if the crew remembers that the takeoff configuration warning horn is only armed when the airplane is on the ground,'' the notice said. ''If this horn is activated in flight, it indicates that the cabin altitude has reached 10,000 feet.''

International Herald Tribune

Posted: Sat Sep 10, 2005 11:54 pm
by c170b53
Most Boeings have two pressurization controllers. if one does not keep the sked the other takes over. Alerts at 10k, cabin altitude is annunciated, aneroids drive the outflow valve closed at 11K and a backup at 15K regardless of mode.

Posted: Mon Sep 12, 2005 5:05 pm
by zero.one.victor
Hard to believe that professional pilots would continue to climb &/or proceed en route when something was obviously (and loudly) wrong. Regardless of the poor CRM due to the language barrier. And that language thing seems like it coulda/shoulda been prevented by some sort of airline policy re: crew compatibility. Maybe that's not generally a problem, but with an intra-national flight crew perhaps it should be considered.
(It's sure way easy to do the monday-morning quarterbacking-- shame on me! :oops: )

Eric

Posted: Tue Sep 13, 2005 1:38 am
by mrpibb
aneroids drive the outflow valve closed at 11K and a backup at 15K regardless of mode.
.

The newer Boeings (after the 727-100's ) if switched to manual the outflow valve will stay where it was last comanded, the outflow valves are now powered by one A/C and one D/C motor ie. manual A/C or manual D/C. So if the rotary switch was left in A/C manual or D/C manual it's a possibilty.

One more tidbit Auto uses the A/C motor and Standby will use the D/C motor.

Posted: Tue Sep 13, 2005 3:00 am
by c170b53
There's aneroids in the controllers to drive the ac motors, aneroids in the control panel to drive the DC motor regardless of switch position to close the outflow valve in the event of excessive cabin altitude.
As for the lingo barrier right in front of the Capt would be a red discrete Cabin Altitude with the warning horn and EICAS msg depending on type. But its possible that neither pilot could read English. The motor vehicle test here can be taken in Punjabi but all the signs on the road are fortunately still English.

Posted: Tue Sep 13, 2005 9:44 pm
by c170b53
Oh-Oh I'm wrong on this one what I previously described is the 767 system. And the previous comment about a manual selection is correct. There's a single controller, aneroids in the outflow valve for the ac motor and the dc motor controlled directly by the Flt deck manual selector. Sorry for the confusion.

Posted: Wed Sep 14, 2005 3:52 am
by GAHorn
Now I'm confused. (And I don't speak/read German or Turkish.) 8O

ADERNOIDS

Posted: Mon Sep 19, 2005 5:05 am
by flyguy
BY OLE '52 GOTS SUM BREATHIN PROBLEMS TOO. HER ADNEROIDS IS ALLUS STOP UP AND DOANT RECURKILATE THE AIR TOO GUD. MEBEE THEY GOT SWITCH FROM SUM OLE "A" MODEL AN THAS WHY I GO TU SLEEP AT THU WHEEL. AN WHEN I FALL BAK OFF MY LETTUCE CRATE AN PULL BAK ON THU STIK THE STALLY HORN BLARES ME AWAKE ANT HEN I SAY SUM FORIEN SOUNIN TALK THAT I CAN' T REPEET HYEAR :lol: