THE HELIOS trial started ticking yesterday with the defence seeking to dismantle the argument that the two pilots of flight ZU522 were guilty of a string or errors that ultimately led to the August 2005 air disaster.
On behalf of the airline, defence attorney Giorgos Papaioannou shifted attention to the poor layout of the Boeing 737’s instrumentation panel, saying it was both awkward and confusing to pilots.
According to the prosecution (the Attorney general’s office), the crew of the ill-fated plane, Captain Hans-Jurgen Merten and his co-pilot Pambos Charalambous were unfit to fly, and therefore it is the airline’s fault for allowing them to do so.
The defendants have all pleaded not guilty. They face charges of manslaughter and causing the death of 119 people through a reckless act. Manslaughter carries a maximum penalty of life imprisonment.
A subsequent fact-finding report attributed the crash to loss of pressure (or decompression) in the cabin, which resulted in the pilots gradually losing consciousness due to lack of oxygen. Based on this, the Attorney-general’s office is arguing that the two aviators did not take the necessary action, despite warnings on their overhead panel.
From the outset, the airline has attributed the accident to the poor design of the panel in the cockpit of the Boeing 737-300.
This type of aircraft uses the same intermittent warning horn sound to warn of incorrect takeoff configuration while on the ground and to warn of cabin pressure problems while airborne.
Once the horn sounds, flight crew should immediately don their oxygen masks.
In a number of documented cases – including that of Helios – the simultaneous message “Equipment Cooling” added to the confusion further delaying the necessary action of donning the oxygen masks.
In court yesterday, the defence tried to show how the two pilots could not be held responsible because, in hindsight, the information available to them was inadequate.
Papaioannou quoted from the QRH (Quick Reference Handbook) issued by Boeing in 2005 describing how in the event of a loss of airflow, or loss of pressure in a 737’s exhaust, the ‘Master Caution’ as well as the ‘No Exhaust’ warnings light up. The manual added that “no further action is required.”
In May 2008, almost three years after the Helios accident, Boeing released an updated QRH noting that such a sequence “may indicate a pressurisation problem.”
It was therefore not be the pilots’ fault that they were operating based on an older, and different, manual that recommended no further action.
Papaioannou was grilling Theofanis Karathanasis, a Greek avionics expert who previously told the court that, in his opinion, the two pilots should have suspected something was amiss when the gauges began flashing.
The defence attorney tried to get Karathanasis to concede that the two Boeing manuals were contradictory; the witness said that, rather, one complemented the other.
Next, Papaioannou brought up the scenario of an equipment cooling problem, which was one of the warnings recorded aboard ZU522. In this case, the ‘Master Caution’ gauge as well as the ‘Overhead’ gauge light up. Oxygen masks drop within seconds. The flight crew then depresses the ‘Master Caution’ button, which resets (turns off) both it and the ‘Overhead’ gauge.
But in a 737-300, the warning gauge for the oxygen masks stays on even after the ‘Master Caution’ button is reset. Because this gauge is located outside the pilots’ line of vision – in fact it is located behind them – hence the pilots do not immediately know if the problem has been corrected or not, Papaioannou told the court.
According to the defence attorney, this was yet another example of bad design by the plane’s manufacturer.
Asked whether he agreed, the witness acknowledged the point, but said that when pilots troubleshoot a problem they also draw on their experience and judgment, not just from the manual.
