B733, en-route, northwest of Athens Greece, 2005

B733, en-route, northwest of Athens Greece, 2005

Summary

On 14 August 2005, a Boeing 737-300 was released to service with the cabin pressurisation set to manual. This abnormal setting was not detected by the flight crew involved during standard checks. They took no corrective action after take-off when a cabin high altitude warning occurred. The crew lost consciousness as the aircraft climbed on autopilot and after eventual fuel exhaustion, the aircraft departed controlled flight and impacted terrain. The Investigation found that inadequate crew performance had occurred within a context of systemic organisational safety deficiencies at the Operator compounded by inadequate regulatory oversight.

Description

On 14 August 2005, a Boeing 737-300 (5B-DBY) being operated by Helios Airways on an international passenger flight from Larnaca to Athens as HCY522 lost contact with ATC en-route and was subsequently intercepted when level at FL340 by two military aircraft, one of whose pilots observed in day VMC that the two 737 pilots were respectively incapacitated and absent from the flight deck. The aircraft subsequently departed controlled flight and impacted terrain almost three hours after take-off and was destroyed and all 121 occupants were killed.

Investigation

An Investigation was carried out by the Greek Air Accident Investigation and Aviation Safety Board AAIASB. Data from the FDR and from the 30 minute CVR were recovered but the latter "was insufficient to provide key information that would have clarified the chain of events during the climb phase of the flight". Useful data was obtained from the NVM of the No. 2 Pressure Controller - that from the No 1. Controller was damaged beyond use.

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