Cockpit confusion in Cypriot air crash: no common language

Harold F. Schiffman haroldfs at
Wed Sep 7 17:50:05 UTC 2005

>>From the NYTimes,  September 7, 2005

Cockpit Confusion Found in Crash of Cypriot Plane
International Herald Tribune

PARIS, Sept. 6 - 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 pressurizing until they grew
mentally disoriented because of lack of oxygen and lost consciousness,
according to several people connected with the investigation into the
crash. 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 the other's 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 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
to fall. So far, the Greek authorities have hinted at oxygen problems but
have not announced the full findings of investigators.

The people interviewed for this article agreed to speak only on the
condition that they not be identified because none are official spokesmen
for the investigation and because of political sensitivities arising from
a Cypriot plane's crashing in Greece. Investigators pieced together the
story of the crash from many 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 information 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
one of the lesser threats facing the plane. The plane that crashed, a
Boeing 737-300, 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 properly.

At 10,000 feet, an alarm went off to warn the crew that the plane would
not pressurize. Crew members mistakenly 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 it will sound for takeoff configuration only while the plane is
still on the ground.

The climb continued 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 captain
and co-pilot discovered that they had no common language and that their
English was not good enough for the complicated technical conversation
required to fix 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 lost consciousness 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 emphasize to crews that they must understand how the various
warning systems work and what to do about them.

The notice emphasizes 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."

Copyright 2005 The New York Times Company

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