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A 2005 fatal accident involving a European airline has since become a tragic case study in how not to manage the delicate balance between technical accident investigation and related judicial action.
The story of the accident flight - in the hands of a documentary film-maker - became notorious as "The Ghost Plane". The accident in August 2005 involved a Helios Airways Boeing 737-300 flight from Cyprus to Athens, and the film title reflected the fact that, during the climb out of Larnaca, the crew and passengers drifted into unconsciousness because the cabin remained unpressurised. Meanwhile, the aircraft's programmed flight director guided the 737 serenely all the way to its final approach fix for Athens where it took up the pre-set holding pattern. There, it was intercepted by Greek air force fighters whose pilots reported back that everyone on board appeared motionless and the passenger oxygen masks were visibly deployed. The 737 eventually crashed because it ran out of fuel, but even during the descent the drama was not over; one conscious member of the cabin crew, who was known to be training for a pilot licence, was observed to have accessed the flight deck and was trying to intervene. Unfortunately, he failed to prevent the crash.
The drama is still not over. Differences between the official accident investigation report and subsequent independent studies into the accident provide an interesting perspective on the relationships - during the accident investigation process - between the official investigation team, the aircraft manufacturer, and the on-board equipment suppliers. Those who assume accident investigation is always an honourable and meticulous game in which decision-making is inevitably clear and always black and white will find that this case does not meet that description.
Meanwhile, the Greek judiciary continues its long quest to apply criminal labels to airline employees, despite international condemnation of both its "quasi-legal" processes and the assumption that accidents must automatically involve criminality. The respected International Association of Air Safety Investigators, while maintaining neutrality in disputes over the technical investigation's findings, has unreservedly condemned Greece for its judicial obsession with finding criminality where there is no evidence of it.
The conclusion of the investigation carried out by the Greek Air Accident Investigation and Aviation Safety Board (AAIASB) was fairly simple. The aircraft, the AAIASB reported, failed to pressurise because the pressurisation mode switch (PMS) was set to manual ("MAN") when it should have been in automatic ("AUTO"), and the pilots missed three checklist opportunities to correct this before becoming airborne. Then when the pressurisation warning horn sounded during the climb, the crew dismissed it as a spurious take-off configuration warning, because the sound is the same. Also, their attention was diverted by another secondary symptom of failure to pressurise - which they unsurprisingly failed to recognise for what it was - and the aircraft continued the climb until the crew were unconscious.
INCORRECT SETTING
So the AAIASB's entire case rested on the contention that the pressurisation control system did not actually fail, it was just set incorrectly. The proposition was that because the PMS was set to MAN and the crew did not manually operate the system's outflow valve (OFV) as necessary to ensure pressurisation took place, the aircraft remained unpressurised. The AAIASB's argument for that conclusion is that the PMS selector knob was found at MAN among the wreckage. In fact, the post-crash position was not found pointing precisely at MAN, it had been driven by the impact to a position beyond the MAN setting.
The AAIASB verdict also presumed the crew must have believed the switch was set to AUTO, but had never checked that it was, despite the fact that three separate check procedures, from pre-start to after take-off, directed the pilots' attention to the PMS settings. The default setting is AUTO; MAN is used only for specific purposes which did not apply to this flight. If the PMS was actually set to AUTO - and the crew acted throughout as if it were - the investigation's conclusions about why pressurisation did not take place would have been radically different, and so would the consequences for manufacturer Boeing, for all 737 operators, and for the manufacturer of the air conditioning and pressurisation system, Germany-based Nord-Micro.
JUDICIARY PROCEDURES
Soon after the 2005 accident, the Cypriot and Greek judiciaries began the highly publicised (in the press) process of identifying individuals for criminal prosecution. In both cases, they chose at least one Helios board member, the airline's chief pilot, the operations manager and, in the Greek case, the head of engineering. The Greeks in particular made no attempt to test any evidence, they unashamedly took the text of the accident investigation as if it were legal evidence, although it is gathered for difference purposes (to prevent recurrence, not to establish blame), and in technical investigations, although evidence and exhibits are respected, the rigid procedures that judicial proof demands are not required to be followed.
In this heated atmosphere, and because some of the expert parties to the investigation disputed the finding that the pressurisation control was mis-set, the technical evidence was independently reviewed by a Canadian company, Accident Investigation and Research (AIR). AIR found that there was physical evidence imprinted upon the overhead panel fascia beneath the PMS selector knob that showed its pre-impact position had been at AUTO, and the crash had turned it to the right through 100 degrees to its post-impact position beyond the MAN setting. AIR observed the original investigation had not even attempted to establish what the knob's pre-impact position had been.
The AAIASB official report also said that a green annunciator light on the PMS panel had been illuminated at impact, warning that MAN was set, but AIR 's conclusion was that the filament in the light bulb had broken from a cold state at impact, indicating it was not illuminated. Finally, AIR said that failure messages derived from the pressurisation control system's non-volatile memory (NVM) indicated an actual system failure, and pointed out that, a few days before the accident flight, the same airframe had suffered a pressurisation system failure. The AIR report said this, "The non-volatile memory of the accident aircraft's digital cabin pressurisation control system (DCPCS) recorded a Fault Code Failure 'AUTO CHANNEL FAILURE', which is classified as 'A system failure has been detected', which was not referenced in the [AAIASB] official accident report, apparently because it was ignored by Nord Micro. This was characterized by a Nord Micro specialist as a mistake in the NVM recording. This Fault Code in the NVM actually clearly confirms a malfunction had occurred in the pressurisation system."
AIR's argument is that there is a significant amount of new evidence that was never considered by the AAIASB, so the investigation should be re-opened. It also alleges that the AAIASB relied too heavily on the expertise of Boeing and Nord Micro, arguing, "The Board's findings as to cause were heavily dependent upon the technical analyses provided to them by Boeing and by Nord-Micro experts." It is, however, normal in an investigation for the manufacturers to be consulted for their expertise.
Helios cabin switches
CONTENTIOUS ISSUES
The UK Air Accident Investigation Branch (AAIB) was a party to the investigation because the Cyprus Department of Civil Aviation (DCA) had delegated safety oversight for Helios and two other local airlines to the international division of the UK Civil Aviation Authority. In fact, the CAA's delegated expert in Cyprus was Capt Pat Richarson, an experienced senior flight operations inspector, who has an air transport pilot licence with ratings for all the Boeing 737 variants. In a written witness statement, she explained, "There was an advisory contract between the UK CAA and DCA Cyprus. Part of that contract was to give regulatory advice to the DCA on three major airlines, Cyprus Airways, EuroCypria and Helios on flight operations matters. I carried out these inspections/audits in accordance with the schedule. These were always carried out at the operators' premises at Larnaca airport. If there were any findings they were emailed to the DCA, and even if there weren't any findings, a report still went to the DCA." She stated that she "spent three years making sure that Helios complied with European Joint Aviation Requirements". If anything required action, the DCA was advised of it, she said. The AAIASB report confirmed that the airline, the aircraft and its crew were in compliance with all requirements.
DIFFERING OPINIONS
Following publication of the AIR report, the chief inspector at the UK AAIB, Keith Conradi, commented on one of the proposed accident causal factors in the original AAIASB report, namely "non-recognition [by the pilots] that the cabin pressurisation mode selector was in the MAN (manual) position". Conradi said of this, "More than anything, this new report sheds significant doubt on that causal factor, and I believe serious consideration should be given to re-opening the investigation." Conradi did not, however, go as far as saying he accepted the AIR interpretation of evidence on the PMS switch position, the light bulb evidence, or the NVM evidence. Perhaps he was content to let that be tested at a re-opened investigation.
Meanwhile, a factor cited in the original report which was declared by the Greek judiciary to be significant was that, before the accident flight, maintenance technicians had tested the pressurisation system on the ground by setting the PMS to MAN, and allegedly had not reset it to AUTO when the task was completed. Even if that were definitely true, the technicians would not be at fault because the maintenance manual contained no requirement to reset it to AUTO. However, the engineer in charge of the pressurisation check stated, on oath in court years later, that it actually had been reset to AUTO. That did not stop the Greek court from convicting him of manslaughter.
A more useful question for the AAIASB and the judiciary to investigate might have been why the maintenance team were having to carry out pressurisation checks on the aircraft at all. The reason was a series of post-flight technical reports filed by crews about repeated recent problems with the pressurisation system in that particular airframe. On the occasion in question, the engineers were checking whether the cause was leakage at one of the aircraft rear doors, because the cabin crew reported noise there. They found that there was no leak. However, the significance of the fact that - if the door was not leaking - the problem must have been elsewhere in the pressurisation control system, appears to have eluded both the AAIASB and the judiciary.Helios Airways was a Cypriot airline, and the 737 was registered there (5B-DBY), so although the accident happened in Greek airspace, the Cypriot judiciary also decided to test the case for criminal liability. The Cyprus case, including an appeal, was heard between 2009 and 2011, and all four accused - Helios chairman Andreas Drakos, chief executive officer Demetris Pantazis, chief pilot Ianko Stoimenov, and operations manager Giorgos Kikkides - were found not guilty of manslaughter and negligence.
BURDEN OF PROOF
However, almost immediately after the Cypriot verdict was delivered, the Greek courts charged Pantazis, Kikkides, Stoimenov and chief engineer Alan Irwin with manslaughter. All were found guilty, but Irwin was cleared later on appeal. The sentence on Pantazis, Kikkides, and Stoimenov was 123 years each in prison, which was commuted to a fine of €80,000 each, which Stoimenov confirms they have been required to pay although the case is still on appeal in the Greek Supreme Court. The court ruling must be delivered by 13 August - within eight years of the event - or the entire case against the accused lapses.
Pantazis has since told Flightglobal "The court decided that the accident happened because the flight crew was incompetent; they were assumed to have made a series of checklist omissions, and subsequently misidentified the dual purpose warning horn as a false take-off configuration warning. The prosecution did not seek to prove the causes of the accident, but relied entirely, with the court's approval, on the Greek Annex 13 Final Report. Conversely, the defence was required to disprove the charges independently. In other words, the defendants were assumed to be guilty unless they could prove they were innocent."
