Lost Souls of Grammatiko: The crash of Helios Airways flight 522 - Article by Admiral_Cloudberg

“Helios 522, do you read?” These immortal words, spoken again and again in futile expectation of a reply, have since come to embody one of history’s most haunting air disasters, one which played out in the sunny skies over Greece on the 14th of August, 2005. It was a catastrophe unlike almost any other: a Boeing 737 full of passengers, circling on autopilot off the coast of Athens, in complete radio silence with no one at the controls. In the windows, people lay slumped over, unmoving; the captain’s seat sat empty; and yet the engines continued to run, propelling the plane around and around until it ran out of fuel. Fighter jets followed it down, watching as it glided to its doom, when, to their amazement, a person appeared in the cockpit—a mysterious figure, not one of the pilots, who sat in the left seat and whispered desperate “mayday” calls until the end, unable to stop the plane from crashing. Who was this lonely soul still clinging to life aboard a ghost plane? What horrible fate had befallen the passengers and crew? These questions would haunt both Greece and the world, as investigators pieced together a sad tale of errors and missed opportunities which sent the 737 and its unconscious occupants gliding silently into the golden crown of Grammatiko Hill. ______________________________________________________________ You can also read this article on Medium.com (link in Reddit comments). Images are sourced from the Cyprus Mail, Nations Online Project, Mila Daniel, justplanes.com, the AAISB, AP, Mayday, TheFlightChannel, the Bureau of Aircraft Accidents Archives, 11Aviation Videos, EMAK, Milos Bicanski, the Greek Herald, Reuters, Louisa Gouliamak, NBC News, and Orthodoxia News Agency. Visit r/admiralcloudberg to read over 220 similar articles!

In the placid waters of the eastern Mediterranean, some one hundred kilometers from the coasts of Turkey and Syria, lies the island nation of Cyprus, the European Union’s most isolated member, and one of its smallest. Once an Ottoman territory, then a British colony, now an independent nation, Cyprus’s modern history has been marked by a tragic conflict between its Greek-speaking south and its Turkish-speaking north, leaving the island divided and quashing local dreams of being annexed by Greece or Turkey. Independent initially against its will, Cyprus has made do, becoming an alternative holiday destination despite the UN-demarcated no-man’s land which still snakes across the island and through the streets of its capital. If one wants to fly to Nicosia, the capital and largest city of Cyprus—(the unrecognized state of Turkish North Cyprus, as the other half is known, also claims Nicosia as its capital, but controls very little of it)—then one must first fly to another city, then drive the rest of the way. Nicosia’s international airport, which lies inside the demilitarized zone, has been largely abandoned since the war which divided the island in 1974, its run-down and dust-covered terminal buildings still decked out in early ‘70s interior décor. Most international flights to Cyprus land in Larnaca, the country’s third largest city and home to its most developed airport. It was no surprise, then, that this was the place where, in 1998, a local businessman decided to found Cyprus’s first independent and first low-cost airline, christened Helios Airways, after the ancient Greek god of the sun.

(Above: 5B-DBY, the aircraft involved in the accident, photographed three days before the crash.) Helios Airways began as a scrappy startup, and never really stopped being one. It claimed to offer tickets for half the price of those sold by Cyprus’s state-owned flag carrier, making it an attractive option for budget-minded European travelers looking for a cheap summer getaway. Its fleet initially consisted of two third-generation Boeing 737-800s, as well as a leased Airbus A319 belonging to another airline. Later, in 2004, the airline added a third Boeing 737, a second-generation -300 model built in 1998 and registered in Cyprus as 5B-DBY. By all accounts, the introduction of 5B-DBY was rushed and disorganized. The United Kingdom Civil Aviation Authority, which had been contracted by the Cyprus Department of Civil Aviation to perform a number of regulatory functions, expressed repeated concerns that paperwork was not in order and that the timeline for the plane’s introduction was unrealistic, as company executives insisted on having it ready by the summer travel rush. Despite the warnings, however, 5B-DBY indeed carried passengers in the summer of 2004, although not without its fair share of issues. In fact, the 737-300 was plagued by gremlins from the very beginning. Mechanics were unable to identify the root cause of many of the problems, which finally culminated in an incident serious enough to warrant outside investigation. In December 2004, 5B-DBY was moments away from beginning its descent into Larnaca after a flight from Warsaw when a loud bang was heard. Within seconds, the air rushed out of the cabin and the passenger oxygen masks automatically deployed. Recognizing that an explosive decompression had occurred, the pilots donned their own oxygen masks and initiated an emergency descent. As the plane lined up for landing, the aft flight attendants reported a concerning discovery: a hole had opened up in the seal around the right rear (R2) passenger door, big enough to stick a hand through (not that anyone was fool enough to try). The flight subsequently landed safely, and three passengers were treated for minor injuries.

(Above: Helios Airways promotional material used the catchphrase, “Here comes the sun!”) An investigation by the Air Accident and Incident Investigation Board of Cyprus was unable to determine the reason for the explosive decompression, but regardless of the cause, the airplane required major repairs. However, after the incident, 5B-DBY’s chronic difficulties only got worse. Pilots reported constant problems with the equipment cooling system. At the same time, air was still leaking out somewhere, and the automated pressurization system kept throwing out errors. Mechanics probably never saw the error messages, which were buried in an electronic menu that they didn’t normally open. But from time to time, the issue surfaced in a manner which was visible to the crew, and then the plane would find itself back in for yet another round of unscheduled maintenance. Early on the 14th of August 2005, the problems struck again. On a red-eye flight from London early that morning, the aft cabin crew heard banging sounds coming from the R2 door and observed ice forming around the door seal. After the flight landed in Larnaca at 3:25 a.m. local time, the problems were recorded in the technical log, and the plane was handed off to Helios Airways maintenance personnel for servicing. In charge of that effort would be British ground engineer Alan Irwin, a highly experienced mechanic who had previously worked for several large European carriers. Given the door’s history, it was clear to Irwin that the sounds and presence of ice probably had something to do with a leak in the door seal. But when he inspected the door, he couldn’t find anything obviously wrong with it. To locate the leak, he would have to scale up the search by conducting a pressurization test.

◊◊◊ Like all airliners, the Boeing 737’s cabin is pressurized in order to ensure that the occupants can breathe at high altitudes, where the outside air is less dense. Contrary to popular belief, however, no airliner is a perfect pressure vessel; in fact, if they were, the passengers would use up all the oxygen and succumb to carbon dioxide poisoning. The air in the cabin is in fact in constant motion, entering the fuselage through the bleed air intakes in the engines and exiting through outflow valves in the front and rear. Some air also escapes through various seals, through the toilets, and through other minor vents, cracks, and openings. Although the passengers don’t normally notice, the air in an airplane cabin is completely replaced via this cycle every few minutes. During a normal flight, the pressurization process is handled automatically by the plane’s electronic pressure control system. Prior to takeoff, pilots simply enter the planned cruising altitude and the altitude of the destination, and the system calculates exactly how much and for how long it will need to open the main outflow valve in order to maintain a comfortable cabin pressure throughout the flight. It will even automatically regulate the rate of depressurization during the descent based on the height of the destination airport, ensuring that uncomfortable ear-popping is kept to a minimum. However, if something is wrong with the automatic system, or if maintenance personnel want to test the integrity of the pressure vessel, it is also possible to control pressurization manually. This is accomplished by moving the pressurization mode selector switch on the P5 pressurization panel from “AUTO” to “MAN,” allowing a pilot or mechanic to directly control the position of the outflow valve. This was what the engineer intended to do aboard 5B-DBY.

Having gathered two other mechanics, one to watch the door from the inside and another to watch from the outside, Irwin moved the pressurization switch to “MAN,” closed the outflow valve, and turned on the auxiliary power unit, the plane’s backup generator. He then used the APU to start the air conditioning packs in order to draw air into the cabin. Within minutes, the pressure inside the plane began to increase, rising toward the nominal in-flight differential pressure 8.25 psi. Nevertheless, neither engineer was able to hear any sounds of air escaping near the R2 door, and the system was able to hold the pressure just fine. Writing off the test as inconclusive, he let the pressure differential return to zero, although not without accidentally hurting the assistant engineer’s ears in the process. After the test, Irwin wrote in the technical log, “Door and local area inspected. NIL defects. Pressure run carried out to max diff…. No leaks or abnormal noises,” along with information about the pressure values used and the procedures followed. The problem hadn’t been solved, but he had done all he could. After releasing the plane for service, he went back to the office, believing that he had restored the airplane to its original configuration. But, as it turned out, he hadn’t.