By George Psyllides
Dubbed the ‘ghost flight’, the causes of the Helios Airways Flight 522 crash which killed all 121 people initially baffled experts.
The Boeing 737-300 had departed Larnaca airport on the morning of Sunday, August 14, for Prague travelling via Athens.
It crashed at 12.03pm near the village of Grammatiko, around 30 kilometres from Athens international airport, killing all 121 – 115 passengers and six crew – on board.
Two Greek F-16 fighter planes had already been scrambled and intercepted the aircraft at 11.24am.
The F-16 pilots reported that they could not see the captain, while the first officer seemed to be unconscious and slumped over the controls.
The passenger oxygen masks were seen dangling and three motionless passengers were seen seated wearing oxygen masks in the cabin.
No external damage or fire was noted and the aircraft was not responding to radio calls.
At 11.49am, one of the F-16 pilots reported a person not wearing an oxygen mask entering the cockpit and occupying the captain’s seat.
A minute later, the left engine flamed out due to fuel depletion and the aircraft started descending. At 11:54am two MAYDAY messages were recorded on the Cockpit Voice Recorder.
The second engine flamed out at 12pm, while the aircraft was at an altitude of around 7,100 feet.
The Boeing crashed into hilly terrain three minutes later.
The person in the cockpit was Andreas Prodromou, 25, a flight attendant and trainee pilot who was desperately trying to save the plane.
One of the F-16 pilots, Panayiotis Athanasopoulos, caught Prodromou’s attention and signalled to him to land.
The steward merely pointed downward with his right index finger, the Greek pilot told investigators later.
He then “looked ahead and did not look towards me again as the plane went down”.
Athanasopoulos described how the aircraft levelled before the crash, hitting the ground on its belly. It slid for a bit before the fuselage started falling apart.
The cockpit then broke off from the rest of the aircraft and “shot away like a meteorite,” Athanasopoulos said.
But why was the crew incapacitated?
The flight departed Larnaca at 9.07 for the leg to Athens with a planned flying time of one hour and 23 minutes.
As the aircraft climbed above 10,000 feet, the cabin altitude alert horn sounded.
Cabin altitude is usually held around 8,000 feet.
The crew mistook it as an erroneous takeoff configuration warning because of the identical sound.
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 problems communicating with each other.
They contacted the airline’s maintenance base to seek advice.
The engineer explained 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 and he left his seat to look for the circuit breaker.
The crew were not wearing their oxygen masks as their mindset and actions were apparently determined by the preconception that the problems were not related to the lack of cabin pressure.
As the Boeing was still climbing, the lack of oxygen seriously impaired the flight crew.
The captain probably became unconscious while trying to find the breaker.
Because the plane’s autopilot was programmed for FL340 (Flight Level 34,000 feet) the Boeing continued to climb until it levelled out at that altitude some 19 minutes after takeoff.
At 09:37 the 737 entered the Athens FIR but no contact was established with the flight.
All efforts by Greek air traffic controllers to contact the pilots were futile.
When it was intercepted by the F-16s, the aircraft was in its sixth holding pattern.
The subsequent investigation discovered that the pilots had failed to adequately monitor the pressurisation system.
Before the ill-fated flight, Helios technicians did a pressure check but failed to reset the pressurisation system from manual back to auto after the test was completed.
When the plane was put back into service, flight crew overlooked the error during the pre-flight procedure, the after-start check, and the after take-off check.
The plane lost cabin pressure and hypoxia caused the incapacitation of the passengers and flight crew.
It is thought that Prodromou had used multiple crew oxygen cylinders to outlast the others on board.
Greece’s air accident investigation board determined that the accident was the result of direct and latent causes.
The direct causes were the flight crew’s failure to spot that the cabin pressurisation mode selector was in the wrong position, failure to identify the warnings and reasons for the activation of warnings – cabin altitude warning horn, passenger oxygen masks deployment indication, master caution – and incapacitation due hypoxia, which saw the flight continue via the flight management computer and the autopilot, depletion of the fuel and engine flameout.
The latent reasons focused on the operator’s deficiencies in the organisation, quality management and safety culture. The investigators highlighted the regulatory authority’s inadequate execution of its safety oversight responsibilities; inadequate application of crew resource management principles, and the ineffectiveness of measures taken by the manufacturer in response to previous pressurisation incidents in the particular type of aircraft.
An independent inquiry conducted by former judge Panayiotis Kallis in Cyprus, found that although the pilots were directly responsible for the crash, the airline, as well as civil aviation officers were criminally liable.
The 170-page report, released in 2011, days after a criminal court held in Cyprus cleared four Helios officials of any wrongdoing, blamed the company for not ensuring the safety of its passengers.
Many witnesses testifying before the Kallis panel, claimed the two aviators, Captain Hans-Jurgen Merten and co-pilot Pambos Charalambous, had trouble communicating due to a clash of personalities but also due to the language barrier.
“Arguably, it was predictable that the situation posed an immediate danger for the safety of others. Not only did they [the airline] allow the two operators to fly, but moreover they paired them together.
“They paired together the couple of doom and destruction,” the report said, concluding that this constitutes the crime of reckless endangerment leading to death.
The Kallis inquiry also found that seven members of the Department of Civil Aviation (DCA) were criminally liable for the disaster.
The report said that then DCA director Stelios Vassiliou (for the period up until December 2004), and deputy director Iacovos Demetriou (from January 1, 2005 until the date of the accident) “failed to put in place” adequate inspection mechanisms in their department, as required by law, and that as a consequence they did not receive “even the most basic of briefing”.
The two men in question “neglected to be briefed on the results of inspections” and their “indifference was such that it can easily be construed that it harmed the public interest in a way that requires censure and punishment.”
The report said this pointed to the “existence of criminal liability” on the grounds of dereliction of duty.
Five employees of the DCA (Stelios Andronikou, Marios Panteli, A. Varley, J. Taylor and A. Paspalides) were considered liable for dereliction of duty, for failing to inform their superiors on what steps were necessary in order to keep Helios Airways in line with airworthiness and flight safety standards.
The report was not legally binding and in any case came out after the criminal case in Cyprus had been concluded.
Four Helios officials – former chief pilot Ianko Stoimenov, chairman of the board Andreas Drakos, chief executive officer Demetris Pantazis, and operations manager Giorgos Kikidis – were brought up on 119 charges of manslaughter and death by negligence.
The four were acquitted of all charges in December 2011, after the court concluded that there was no causal association between them and the causes of the accident.
Shortly after the trial in Cyprus, a trial in Greece started since the plane crashed on Greek soil.
Demetris Pantazis, Giorgos Kikkides, Ianko Stoimenov and chief engineer Alan Irwin were charged with manslaughter and were eventually found guilty in April 2012, and sentenced to 10 years in jail.
They appealed the verdict but lost the case before the Greek Supreme Court.
Under Greek law, however, the defendants were given the option of buying out their sentences. In August 2013, each one of them paid €75,000 and was set free.