ATW Daily News

Helios Airlines 737-300 pilots failed to notice warning signs

Wednesday October 11, 2006

Greece's Air Accident Investigation and Aviation Safety Board said yesterday that the August 2005 Helios Airlines 737-300 crash was caused primarily by the pilots' "nonrecognition" that the cabin pressurization mode selector was switched to "manual" and their subsequent misreading of warning signs.

The errors led to the flightcrew's incapacitation "due to hypoxia" when the aircraft failed to pressurize on ascent. It flew for more than 90 min. on autopilot before its fuel was exhausted and its engines flamed out. "The aircraft continued descending rapidly and impacted hilly terrain...approximately 33 km. northwest of the Athens International Airport," said the Greek government report issued yesterday. All 121 passengers and crew were killed (ATWOnline, Aug. 16, 2005).

The Larnaca-Athens-Prague flight was doomed by a variety of human errors, investigators concluded. The pilots were at fault for not recognizing the cabin pressurization switch's incorrect setting before takeoff and "nonidentification" of warnings once the plane was airborne. Maintenance workers were at fault for failing to return the pressurization mode selector to the "auto" position after performing nonscheduled maintenance.

The Cypriot airline, now called Ajet Airways, was plagued by "deficiencies in...quality management and safety culture." Regulators were guilty of "inadequate execution" of safety oversight. Finally, Boeing was called to task for "ineffectiveness of measures taken by the manufacturer in response to previous pressurization incidents in the particular type of aircraft."

The report said the Cyprus government, Boeing, the Greek Civil Aviation Authority and US FAA have implemented "improved procedures" based on recommendations the Greek safety board issued during the course of its investigation.

by Aaron Karp

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