Last night I watched a very interesting show on National Geographic about aircraft disasters that were tracked to maintenance issues. Now, usually, I don't like watching violent or gory stuff but this wasn't either; a very well constructed show that took you through three different instances (reconstructed parts) that felt like watching a thriller movie.
First incident: Somewhere in the west-coast of the United States: A few minutes after the aircraft was air-bound and the passengers settling into their routine, there was a loud thud and the people on board were in for a shocking sight: the roof of the airplane got ripped off and the plane started tottering dangerously. "The oxygen masks came down but the outside pressure was so huge that the fingers were going numb and the entire head was swathed in excruciating pain", recalled a survivor. The oxygen masks were to last only until 30 minutes, hence the aircraft had to be brought to a lower altitude. The aircraft made a tumultuous rapid descent to lower altitudes and as the oxygen levels resumed to normalcy the pilots are able to gain some control. They managed to maneuver the plane to a nearby airport with great difficulty and landed everyone safely to ground.
Second incident: Fifteen years earlier, a similar catastrophe struck a Japanese aircraft that had 500 passengers on board. The rear of the aircraft blew off mid-air and the passengers faced similar disastrous conditions as in the first incident. But here, even the controls failed as the hydraulic system was damaged due to the rip off. However, the pilots discovered a unique way that could keep the plane moving. When pressure was applied to right engines, the plane swerved slowly to the left and vice-versa. A very difficult way to propel the aircraft, yet the pilots tried to keep the plane in the air for as long as they could. Yet, it was a tall order to get to safety and in addition they encountered a rocky terrain ahead and crashed. Everyone aboard perished.
The entire story was reconstructed to create a dramatic effect and what was even more heart-wrenching was to learn about a little lad of 9 years travelling alone on this ill-fated flight and whose body remained unaccountable for. The parents for a long time believed that the boy somehow escaped the disaster miraculously.
Third incident: In the third instance, a British aircraft was to fly its maiden flight. The aircraft was fitted with brand new window screens just a day ago. As the plane gathered altitude, there was a loud noise from the cock pit and as the steward rushed to see what happened he was met with a horrific sight of the front window plane being blown off and one of the key-pilots sucked into the frame. The pilot was dangling in mid-air with just his legs inside the aircraft. The steward had the presence of mind to hold on to the legs of the pilot. The co-pilot had twin troubles to flying the plane to safety. The nearby airport was unfamiliar to him and he had no help from his co-pilot. There was a motor way close to the airport which could have been confused with the runway. Imagine the chaos going inside the pilot's mind. Through sheer grit, determination and skill, the pilot managed a safe landing. Miraculously, the pilot who was stuck out in the mid-air, subjected to minus degree temperature and cold winds that blew onto his face at unimaginable speed, survived too with some minor fractures on the face and frost bites.
In all the three incidents, the survey team conducted a tough and thorough investigation routine that worked backwards to find the root cause that led to such mishaps in mid-air. Maintenance records were combed in detail. What was uncovered was to take the work done by the aircraft maintenance team to a new level.
In the Japanese incident, it was found out that years before the fatal accident took place, the aircraft had met with an accident on the runway- the tail had hit the runway, causing a dent in the rear end. There was a strict procedural guideline to carry out the repair work, wherein the two ends had to be joined with a single continuous metal plate wedged in between, joined together with rivets at three different levels. The repair was done but not as per the specifications. Instead of a single long metal plate, two smaller ones were used one with two rows of rivets and one with only one row in place. However this arrangement weakened the design and with every flight thence, the crack in the design deepened. The disaster was just waiting to happen one day during one flight.
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| Diagram of correct and incorrect repairs-Wikipedia |
In the third instance, it was discovered that the window screen was secured to the framed with bolts that were narrower than the ones intended by about a small fraction. Yes, just a miniscule of a difference, yet, when the aircraft encounters huge altitudinal pressure, it is sufficient to wedge the seemingly correct bolts off little by little off the groove. The person who fit them worked by comparing the look and feel of the bolt with the original rather than going by the manual and said rules!
In the first instance, the roof of the aircraft that blew off, baffled the investigation team since that area was not deemed to be a critical area under the maintenance rule book. The fatigue cracks that were visible on them were supposed to arise at a much later date. The aircraft had completed 39000 flights and the maintenance team would have carried out the required checks for these kind of warning signals only at the completion of 60000 flights. The rule book was changed therein to carry out these checks at the end of 30000 flights. Not only this, but the team identified similar flights at various locations that were staring at such a disaster and managed to withdraw them before they took their next flight.
I was thoroughly impressed with the manner in which the investigation team carried out their task of working their way backwards to find the root cause given the baffling circumstances in each of the three cases and managing to pin point the fault too. The mistakes when singled out seem like a minor slip off but when in comes to aircraft maintenance, these instances are lessons that drive home the point that nothing at all is unimportant.
Just wondering how good is the safety features in our airlines, Do we have a thorough procedure to follow when in comes to maintenance? Even more important, do we conduct such intensive survey and investigation after a disaster and learn from our mistakes thereafter? A very scary thought indeed!
