HELIOS 737-300 5B-DBY(cn2982)
Athens Eleftherios Venizelos airport..First flight 27/12/1997.On Sunday 14/08/2005 crashed into Varnava Mt. near Grammatikos city (Greece) while approaching Athens Int. Airport . The plane, Helios Flight ZU522 with 115 passengers and 6 crew, was en route from Larnaca, Cyprus, to Prague, Czech Republic, with stop at ATH.Helios' Boeing 737-300 5B-DBY underwent maintenance on the night prior to the accident. The pressurization system was checked, but after completion of the tests the Pressurization Mode Selector (PMS) was reportedly left in the "Manual" position instead of the "Auto" mode. In manual mode the crew had to manually open or close the outflow valves in order to control the cabin pressure. The outflow valves were one-third in the open position which meant that the cabin would not pressurize after takeoff. The PMS mode was apparently not noted during the pre-departure checks by the crew.
In the morning the 737 was to operate Flight 522 from Larnaca to Prague, Czech Republic with an intermediate stop at Athens, Greece. The flight departed Larnaca at 09:07 for the leg to Athens with a planned flying time of 1 hour and 23 minutes. As the airplane climbed over the Mediterranean the cabin altitude alert horn sounded. This occurred as the 737 passed through an altitude of 10,000 feet. Cabin altitude is usually held around 8,000 feet. The crew possibly thought it was an erroneous takeoff configuration warning because the sound is identical. Then, at 14,000 feet, the oxygen masks automatically deployed and a master caution light illuminated in the cockpit. Because of a lack of cooling air another alarm activated, indicating a temperature warning for the avionics bay.
The German captain and the Cypriot co-pilot tried to solve the problem but encountered some problems communicating with each other. They contacted the Helios´ maintenance base to seek advice. The engineer told that they needed to pull the circuit breaker to turn off the alarm. The radio contact ended as the aircraft climbed through 28 900 ft.
The circuit breaker was located in a cabinet behind the captain. The captain got up from his seat to look for the circuit breaker. The crew were not wearing their oxygen masks as their mindset and actions were determined by the preconception that the problems were not related to the lack of cabin pressure.
As the airplane was still climbing the lack of oxygen seriously impaired the flight crew. The captain probably became unconscious when he was trying to find the circuit breaker. The first officer was still in his seat when he also became unconscious. Because the plane's autopilot was programmed for FL340 the Boeing continued to climb until leveling out at that altitude some 19 minutes after takeoff. At 09:37 the 737 entered the Athens FIR but not contact was established with the flight. Over Rodos at about 09:52 the airplane entered the UL995 airway. At 10:21 the airplane passed the KEA VOR, which is located about 28 nm south of the Athens airport. The airplane then passed the Athens Airport and subsequently entered the KEA VOR holding pattern at 10:38. All efforts by Greek air traffic controllers to contact the pilots were futile. Around 11:00 two Greek F-16 fighter planes were scrambled from the Néa Anghialos air base. At 11:24, during the sixth holding pattern, the F-16's intercepted the airliner. The F-16 pilots reported that they were not able to observe the captain, while the first officer seemed to be unconscious and slumped over the controls.
At 11:49, the F-16's reported a person not wearing an oxygen mask entering the cockpit and occupying the captain's seat. The F-16 pilot tried to attract his attention without success. At 11:50, the left engine flamed out due to fuel depletion and the aircraft started descending. At 11:54, two Mayday messages were recorded on the CVR.
At 12:00, the right engine also flamed out at an altitude of approximately 7100 feet. The aircraft continued descending rapidly and impacted hilly terrain.
The same Boeing 737, 5B-DBY, suffered a loss of cabin pressure on December 20, 2004 during a flight from Warsaw to Larnaca. Three passengers needed medical treatment after landing in Larnaca. This incident was caused by a leaking door seal of the right hand rear door.
HELIOS 737-300 5B-DBY(cn2982)
Athens Eleftherios Venizelos airport..First flight 27/12/1997.On Sunday 14/08/2005 crashed into Varnava Mt. near Grammatikos city (Greece) while approaching Athens Int. Airport . The plane, Helios Flight ZU522 with 115 passengers and 6 crew, was en route from Larnaca, Cyprus, to Prague, Czech Republic, with stop at ATH.Helios' Boeing 737-300 5B-DBY underwent maintenance on the night prior to the accident. The pressurization system was checked, but after completion of the tests the Pressurization Mode Selector (PMS) was reportedly left in the "Manual" position instead of the "Auto" mode. In manual mode the crew had to manually open or close the outflow valves in order to control the cabin pressure. The outflow valves were one-third in the open position which meant that the cabin would not pressurize after takeoff. The PMS mode was apparently not noted during the pre-departure checks by the crew.
In the morning the 737 was to operate Flight 522 from Larnaca to Prague, Czech Republic with an intermediate stop at Athens, Greece. The flight departed Larnaca at 09:07 for the leg to Athens with a planned flying time of 1 hour and 23 minutes. As the airplane climbed over the Mediterranean the cabin altitude alert horn sounded. This occurred as the 737 passed through an altitude of 10,000 feet. Cabin altitude is usually held around 8,000 feet. The crew possibly thought it was an erroneous takeoff configuration warning because the sound is identical. Then, at 14,000 feet, the oxygen masks automatically deployed and a master caution light illuminated in the cockpit. Because of a lack of cooling air another alarm activated, indicating a temperature warning for the avionics bay.
The German captain and the Cypriot co-pilot tried to solve the problem but encountered some problems communicating with each other. They contacted the Helios´ maintenance base to seek advice. The engineer told that they needed to pull the circuit breaker to turn off the alarm. The radio contact ended as the aircraft climbed through 28 900 ft.
The circuit breaker was located in a cabinet behind the captain. The captain got up from his seat to look for the circuit breaker. The crew were not wearing their oxygen masks as their mindset and actions were determined by the preconception that the problems were not related to the lack of cabin pressure.
As the airplane was still climbing the lack of oxygen seriously impaired the flight crew. The captain probably became unconscious when he was trying to find the circuit breaker. The first officer was still in his seat when he also became unconscious. Because the plane's autopilot was programmed for FL340 the Boeing continued to climb until leveling out at that altitude some 19 minutes after takeoff. At 09:37 the 737 entered the Athens FIR but not contact was established with the flight. Over Rodos at about 09:52 the airplane entered the UL995 airway. At 10:21 the airplane passed the KEA VOR, which is located about 28 nm south of the Athens airport. The airplane then passed the Athens Airport and subsequently entered the KEA VOR holding pattern at 10:38. All efforts by Greek air traffic controllers to contact the pilots were futile. Around 11:00 two Greek F-16 fighter planes were scrambled from the Néa Anghialos air base. At 11:24, during the sixth holding pattern, the F-16's intercepted the airliner. The F-16 pilots reported that they were not able to observe the captain, while the first officer seemed to be unconscious and slumped over the controls.
At 11:49, the F-16's reported a person not wearing an oxygen mask entering the cockpit and occupying the captain's seat. The F-16 pilot tried to attract his attention without success. At 11:50, the left engine flamed out due to fuel depletion and the aircraft started descending. At 11:54, two Mayday messages were recorded on the CVR.
At 12:00, the right engine also flamed out at an altitude of approximately 7100 feet. The aircraft continued descending rapidly and impacted hilly terrain.
The same Boeing 737, 5B-DBY, suffered a loss of cabin pressure on December 20, 2004 during a flight from Warsaw to Larnaca. Three passengers needed medical treatment after landing in Larnaca. This incident was caused by a leaking door seal of the right hand rear door.