OFFICIALS from ajet, formerly known as Helios Airways, yesterday stuck to their guns over the cause of last summer’s crash, focusing on build deficiencies on Boeing planes.
The company says it has carried out extensive tests strongly showing that it is “near to impossible” for a Boeing 737 jet to take off with the decompression switch on manual, as a report into the accident by Greek investigators suggests.
The tests showed that venturing a takeoff on manual generates so much noise that it bursts passengers’ eardrums, not to mention the fact the hatch door would not shut in the first place.
But Air Accident Investigator Akrivos Tsolakis’ fact-finding report found that the airflow valve was set at a 14 degrees angle from the manual position, allowing for partial pressurisation. For this type of Boeing, it should have been on the auto switch before takeoff.
According to the official version, on the night before the accident ground crew had reset the switch to manual, but on the fateful flight the pilots apparently omitted to conduct the pre-flight checks.
The problem was compounded in the air, when the pilots misread an alarm for a takeoff configuration glitch, because the sound emitted for that is identical to the one for a decompression problem.
Mistaking the alarm for a false takeoff configuration warning – which could not be the case, as the plane was already airborne – the aviators were troubleshooting in the wrong direction, while all the time the plane steadily depressurised, leading to the onset of hypoxia.
Strangely enough, although in his probe Tsolakis mentioned this omission by the engineer, he made no recommendations about Helios, merely noting the airline’s operational deficiencies under the “latent” (not immediate) causes of the crash.
But Helios insists that two series of tests – one in May, the other in August – all but eliminate the possibility the decompression switch was on manual. Both these tests were carried out in England.
The results, they say, were not taken into account in the Tsolakis report.
The company is planning a third run of tests to be supervised by a former UK air accident investigator and aviation expert.
While agreeing that the primary cause of the accident was depressurisation, Helios disagrees with Tsolakis on how this came about.
They say the engineer had set the switch to auto, as required, but the electrical system did not respond due to bad wiring on the plane – i.e. a manufacturing fault.
Thus, the system “read” the switch as being on auto while in reality it was not.
By extension, according to Helios, that would explain why the pilots assumed the decompression configuration was fine. Thus the airline is also ruling out pilot error.
“Either way, whether the switch was on auto or manual, the point is that the accident is not a direct result of the actions/omissions of airline staff,” said Christos Neocleous, a spokesman and lawyer for Helios yesterday.
“I want to make this clear: we are not attacking the Tsolakis report. In fact, we believe it was very professional in all respects. But we do have reservations about these two points, which suggest a lack of a safety culture at the airline,” Neocleous told the Mail.
And even if the engineer on duty had left the decompression switch in the manual position, that person could not be blamed, because Boeing’s manual for 737s was vague on this matter.
Prior to the accident, instead of explicitly instructing ground technicians to reset the decompression switch to auto, the manual simply said that the switch should be set “to the previous position,” i.e. from manual to auto.
Boeing has since updated its manuals to correct this ambiguity.
Asked what the company would do with their findings, Neocleous offered:
“The accident report is final. It cannot be changed.”
But he hinted the airline might seek compensation from the manufacturers. He said wiring problems on 737s had been widely reported prior to the accident, so Boeing should have fixed the problem.
On the other hand, before the accident there had been recurrent problems with the air conditioning system aboard Helios planes, suggesting faulty electrics. Passengers had often complained of freezing, but apparently the airline took no steps to resolve this issue.
Boeing is also being sued in the United States by the relatives of the victims.
