This morning, a report into the crash of Helios Airways 522 — a Boeing 737–315 — was published (or, at least, made available to the press; I can’t find the bloody thing). Over the past few months, I’ve become acquainted with some aspects of aviation safety during research for Flashback, and my girlfriend and I were involved in an incident that somewhat resembles the events that led to the Helios crash on 14th August last year. I thought it might be worth a post. Be aware that this is not a comprehensive review of air safety, and I’m not an expert.
The information available is sketchy, but here’s a summary of what happened on board flight 522. The night before the accident, the aircraft — only eight years old — underwent maintenance. First mistake: Technicians tested the Pressurization Mode Selector (PMS), which is a system that permits pilots to control cabin altitude (i.e. pressure), and left the switch on ‘manual’. Normally, this is set to ‘automatic’, so that the pressurization system adapts as the aircraft climbs. Second mistake: The pilots should have checked this setting during their pre-flight procedure, but they did not.
The next day, 522 took off on its route from Larnaca to Prague, with a stop at Athens. As the aircraft climbed over the Mediterranean, the pilots heard the cabin alert horn. Third mistake: This horn sounds quite like the horn that indicates a takeoff configuration warning (i.e. the computer ain’t happy for some reason), so the pilots ignored it. Meanwhile, cabin altitude, which is usually held at 8,000 feet (not sea-level) began to increase. The pilots carried on regardless. At 14,000 feet, oxygen masks were automatically deployed and the master caution light flashed in the cockpit. On top of this came another alarm: a temperature warning for the avionics bay.
This kind of confusion often precedes catastrophic crashes in modern airliners. A ‘single’ event — here, the failure to maintain pressurization — produces a number of alarm correlates, and it is up to the pilots to turn detectives with a very short deadline. In this case, the captain was a German and the co-pilot a Cypriot; already suffering from hypoxia, they had difficulty talking to one another in English. Fourth mistake: Having discounted the cabin altitude warning alarm as a takeoff configuration error, they did not don their oxygen masks and begin an emergency descent. Instead, they made contact with Helios maintenance engineers and were told to remove the alarm circuit breaker. The captain left his seat to deal with this and probably became unconscious during his search. A short time after, so did the co-pilot. The aircraft continued to climb until its flight management computer knew it had reached cruising height. The computer took the plane into Athens airspace and entered a holding pattern.
The rest is fairly grisly. Because the plane did not identify itself, two Greek fighters intercepted the aircraft and established that the captain was not at the controls and the first-officer appeared to be unconscious. Some minutes later, a steward, who had just begun flying lessons, attempted to take control of the plane. Remember that all the flight attendants would have donned their oxygen masks. Airspeed was increased and the plane banked right. Then it turned left. Having been in the air for three hours, Flight 522 ran out of fuel and crashed north of Athens.
What’s to learn from this flight? First off, I’m not sure whether Helios could be called a ‘budget airline’, but time and again catastrophic (and minor) aircraft accidents result from improper maintenance, which itself is the first to suffer from aggressive cost-cutting that is often a feature of stripped-down fleets. Technician training can be jeopardised, and lower wages attract staff with less experience. Then a mistake like an incorrect PMS system setting can be made (though, in this instance, the pilots should have caught the error). An example of how this directly affects safety is when ground technicians are required to read and digest aircraft safety bulletins posted by manufacturers like Boeing. These are extremely technical documents, and their details are occasionally lost, leading to safety compromises and, when circumstances conspire, fatality. When you pay two Euros one-way for a trip handled by a budget airline, you may not be jeopardising yourself completely, but it’s worth bearing in mind that the pressure of financial margins does have an impact on safety. An airline might have the motto ‘Safety first’ but this cannot be true — in reality, the airline will provide you with as much safety as it possibility can given its financial constraints. ‘Profits first, but you come a close second.’ For your information, Helios is now called Ajet.
I’m not one who likes to collect first-hand research (just ask my old PhD supervisor), but, in early August of this year, my girlfriend and I were on board a plane that was forced to return to its originating airport because an issue that is probably maintenance-related. Just after take off from Rijeka airport, Croatia, our pilot levelled off at a very low altitude. Over the public address, he told us passengers that there had been a technical problem serious enough for him to abandon the flight. No mention was made of what the problem might be. We made a fairly sharp turn and headed back to Rijeka. The most panicky bit came a few seconds later, when the aircraft appeared to make a severe, uncommanded bank to the right. I thought, Hmm, either the pilot needs to avoid a imminent collision or the technical problem relates to the control surfaces, and we’re about die. I knew from my research that a technical problem — however minor — can be related to serious underlying problems that might threaten the integrity of plane. As the captain told us later, somewhat wistfully, these modern aircraft are essentially computers with wings. And do these computers have buggy software? You bet they do. (Though, to be fair, accidents caused by computer errors tend to be misunderstandings between the pilot and the computer.)
Anyway, the problem turned out to be that computer reported the forward door was not ‘armed’ (i.e. shut and verifiably shut). I’ve not heard anything about this flight on air safety forums, but I’d be willing to bet that this was caused by faulty maintenance of the door; i.e. some part of it had failed because it had not been checked or replaced within its engineered life cycle. Lots of other things might have caused the ‘armed’ error, like software bugs or wiring malfunctions, but I prefer not to think of those. For your information, our carrier was budget airline EasyJet — who have been in the news recently for charging customers an arm and a leg (so to speak) when they try to complain about a poor standard of service.
Well, that’s my two cents. Will I end on the message ‘flying is the safest form of travel’? No. Though this is true. I’ll end by repeating some of the advice on last week’s BBC Horizon programme about surviving an air crash: (1) Remember that an aircraft lap belt opens with a pull, not a push like a car belt; (2) Don’t try to find your friends first when asked to evacuate a plane by the cabin crew — go immediately to the exit; (3) Sit yourself within seven rows of a working exit, preferrably one that’s in front of you; (4) Count the number of rows between your seat and the exits ahead and behind so that you can exit if the cabin is filled with smoke; (5) Keep your shoes on.