AKRIVOS Tsolakis, head of the Greek air-accident investigating team for the August 14 crash of a Helios Airways Boeing, was back on the island yesterday.
It is the expert’s third visit to Cyprus, where his team have interviewed dozens of individuals related to the accident, including civil aviation personnel and staff from the concerned airline.
Investigators are still trying to piece together clues from the horrific crash outside Athens, which killed all 121 on board. The predominant theory is that cabin decompression led to hypoxia – or low oxygen in the blood – causing the crew to pass out.
Tsolakis told the Cyprus Mail yesterday that his precise itinerary was not yet fixed, although it is almost certain he would meet with government officials to update them on the course of the probe.
“We’re continuing our work normally,” he said.
Earlier in the week, Tsolakis told Flight International that Greek investigators have discovered there have been many other cases of a Boeing 737 climbing without pressurization set, but the crews recognised the alerts and averted hypoxia and resultant disaster.
Tsolakis said he had received reports from numerous other national aviation authorities advising him of events similar to the Helios one, but with “non-fatal outcomes”.
It is believed that before the doomed flight, maintenance crew who had conducted a pressurisation check left the control in manual instead of automatic, so the aircraft did not pressurise as it gained altitude. But the crew failed to notice the setting in their pre-take-off checks, and the post-take-off checks require no further confirmation of the pressurisation control selection.
In the Helios case, when the audible cabin altitude alert sounded, the crew thought it was an erroneous configuration warning because the sound is identical. According to Tsolakis, the pilots’ “subsequent mindset and actions were determined by this preconception until hypoxia overcame them as the aircraft continued to climb.”
The expert also told Flight International that none of the crew had been exposed to the symptoms of hypoxia in a decompression chamber during any of their training. And early investigations suggest the airline had not drawn up its own codes of operating practice.
The airline has also been taken to task over coroners’ findings that the two aviators suffered from constricted coronary arteries, which may have made them more susceptible to a drop in the oxygen supply.
Meanwhile, Boeing may be asked to account for why, following non-fatal precursor events, no changes were made to the 737 operations manual advice on pressurisation system management, although appropriate amendments have now been issued to operators.
In a related development, the European Commission, Parliament and the Council have reached an agreement on a proposal for a regulation of air carrier identity. The regulation introduces two innovations: a blacklist of airlines which have been banned for safety reasons, and passenger information about the identity of the air carrier which is operating their flight.
The ambitious piece of legislation should be in place by the end of the year. The proposed measures can be imposed without discrimination on all carriers, regardless of whether they are European or non-European.
The measures will be imposed on the basis of common safety criteria that are applicable in all EU member-states, thus giving all passengers in Europe exactly the same guarantees on safety. It is also designed to combat the potential confusion of having separate national blacklists.
In particular, the blacklist will provide useful information for people wishing to travel outside the European Union, where the flight bans cannot be applied, and will give more rights to these passengers. If an airline appears on the blacklist, passengers will be entitled to a refund or to be re-routed to their final destination.
