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Helios Flight 522
Transcript of Helios Flight 522
Helios Flight 522
Aircraft Boeing 737-31S took off from Larnaca International Airport on the Greek Isle of Crete on August 14 2005.
Was headed to Prague Ruzyně Int'l Airport with a layover in Athens, however it crashed 40 km (25 mi) north of Athens
The worst aviation disaster in Greek history in which all 115 passengers and the 6 crew members lost their lives.
Why didn't the crew react?
Shortly after the cabin altitude warning sounded, the captain radioed the Helios operations centre and reported "the take-off configuration warning on" and "cooling equipment normal and alternate off line". He then spoke to the ground engineer and repeatedly stated that the "cooling ventilation fan lights were off". The engineer (the one who had conducted the pressurization leak check) asked "Can you confirm that the pressurization panel is set to AUTO?" The captain, however, disregarded the question and instead asked in reply, "Where are my equipment cooling circuit breakers?". This was the last communication with the aircraft.
Attempts to Contact the Aircrew
Nineteen attempts to contact the aircraft between 10:12 and 10:50 also met with no response, and at 10:40 the aircraft entered the holding pattern for Athens Airport, at the KEA VHF omnidirectional range, still at FL340. It remained in the holding pattern, under control of the auto-pilot, for the next seventy minutes.
Two F-16 fighter aircraft from the Hellenic Air Force 111th Combat Wing were scrambled from Nea Anchialos Air Base to establish visual contact. They intercepted the passenger jet at 11:24 and observed that the first officer was slumped motionless at the controls and the captain's seat was empty. They also reported that oxygen masks were dangling in the passenger cabin.
What caused the accident?
The previous flight crew out of London Heathrow Airport had reported a frozen door seal and abnormal noises from the right aft service door. The inspection was carried out by a ground engineer who then performed a pressurization leak check. In order to carry out this check without requiring the aircraft's engines, the pressurisation system was set to "manual". However, the engineer failed to reset it to "auto" on completion of the test . After the aircraft was returned into service, the flight crew overlooked the pressurisation system state on three separate occasions: during the pre-flight procedure, the after-start check, and the after take-off check. During none of these checks did the flight crew notice the incorrect setting. The aircraft took off at 9:07 with the pressurisation system still set to "manual", and the aft outflow valve partially open.
As the aircraft climbed, the pressure inside the cabin gradually decreased. As it passed through an altitude of 12,040 feet (3,670 m), the cabin altitude warning horn sounded.The warning should have prompted the crew to stop climbing.
What attempts were made to control the aircraft?
At 11:49, flight attendant Andreas Prodromou entered the cockpit and sat down in the captain's seat. Prodromou held a UK Commercial Pilot License, but was not qualified to fly the Boeing 737.
In any case, he did not have time to save the stricken aircraft. Almost as soon as he entered the cockpit, the left engine flamed out due to fuel exhaustion, the plane left the holding pattern and started to descend. Ten minutes after the loss of power from the left engine, the right engine also flamed out, and just before 12:04 the aircraft crashed into hills near Grammatiko. There were no survivors.
Investigation and Remedial Actions
Suspicions that the aircraft had been hijacked were ruled out by Greece's foreign ministry. Initial claims that the aircraft was shot down by the fighter jets have been refuted by eyewitnesses and the government.
The flight data recorder and cockpit voice recorder were sent to Paris for analysis.The Hellenic Air Accident Investigation and Aviation Safety Board (AAIASB) determined that the direct causal chain of events that led to the accident was
non-recognition by the pilots that the pressurisation system was set to "manual",
non-identification by the crew of the true nature of the problem,
incapacitation of the crew due to hypoxia,
eventual fuel starvation,
impact with the ground.
In March 2011, the Federal Aviation Administration in the United States released an airworthiness directive requiring all Boeing 737 aircraft from −100 to −500 models to be fitted with two additional cockpit warning lights. These would indicate problems with take-off configuration or pressurization. Aircraft on the United States civil register are required to have the additional lights by 14 March 2014