Monday, April 23, 2018

Southwest Airlines Flight 1380: Cracks in Airline Safety?

Over the last twenty years or so, the news about airline safety in the U. S. has been mainly good.  Before last week, the last time a passenger died in a U. S. commercial airliner accident was 2009, and for some time before that it's been true that the most dangerous part of a plane trip is the drive to the airport.  But on Tuesday April 17, the explosive decompression that resulted from an engine fan blade on Southwest Airlines flight 1380 hitting a window sucked passenger Jennifer Riordan partway out of the plane, and she later died of her injuries.  Captain Tammi Jo Shults received praise for her calm and expert handling of the crisis, bringing the plane safely to ground in Philadelphia without any other fatalities.  

Good safety records don't just happen.  They are the product of unceasing vigilance on the part of thousands of pilots, mechanics, traffic controllers, inspectors, and other members of a complex system that has to be continually monitored and managed well to make flying safe.  One of the routine measures that helps maintain safety is regularly scheduled inspections of parts of the aircraft subject to fatigue.  Fatigue can happen to any part that comes under mechanical stress during takeoff, flight, or landing.  And some of the most highly stressed parts are in the engine, of course:  the turbine blades that endure extreme centrifugal forces and thermal stress, as well as the fan blades—the big visible ones in the front of the engine in modern turbofan units. 

A turbine blade that breaks off rockets through the housing like a bullet, usually destroying the engine and often damaging other parts of the aircraft.  This happened back in 1989 to a DC-10, and unfortunately the blade happened to hit the fuselage at a critical point that severed all the hydraulic control lines.  Forced to steer only by manipulating the throttles of the remaining engines, the pilots crash-landed at an airport in Sioux City, Iowa. One hundred and eleven passengers died in that crash and 185 survived.

More recently, in 2016 a fan blade on a Southwest 737 from the same type of engine that failed on flight 1380 came loose and knocked away the entire inlet part of the engine.  One of the flying parts ripped a hole in the fuselage and decompressed the cabin, but the pilots managed to make an emergency landing without serious injuries to anyone.  The missing blade was never recovered, but investigation of the root that remained on the hub showed that fatigue cracking had occurred. 

I wasn't able to determine if the NTSB or the FAA issued any directives for increased scrutiny of these blades after the 2016 incident.  But in light of the more serious consequences of last week's accident, government authorities have ordered inspections of more than 700 Boeing 737s that use the CFM56-7B engine.  That is only about 10% of all such engines in use, but there may be technical reasons why only some of the engines need to be inspected.

While Captain Shults deserves praise for her cool handling of the situation, it's typical of media attention to accidents like this that the pilots get their pictures splashed around for taking a bad situation and making it turn out better than it could have, while the people who spend their lives making sure pilots don't have to be heroes remain unheard-of and unsung.  The media thrive on drama and narrow escapes.  You will never see a news headline that reads, "Flight XYZ lands safely on time with no fatalities or injuries," because that is exactly what we expect to happen.  The people I mentioned above who spend their lives making sure that 99.999... % of the time, the normal thing happens never get any public attention, despite the fact that we owe the amazing reliability of air travel to their dedication and diligence.

In the January 2018 issue of the historical journal Technology and Culture, two historians point out that their own profession is guilty of a similar prejudice or blindness.  Historians of technology typically focus on inventions, discovery, innovation, and disruption, and the people responsible for these things.  But Andrew Russell and Lee Vinsel have issued a call for writing histories of the "maintainers":  the people who fix things when they're broken, do regular preventive maintenance so things don't break in the first place where lives can be endangered, and generally keep existing systems and institutions running smoothly. 

I don't know how far Russell and Vinsel will get in their attempt to encourage historians to look at maintenance, but they have perceived the academic version of a general trend that could lead us into a lot of trouble if we let it continue.  It's the neglect of the people who do routine, ordinary, and even dull activities that are nevertheless vital to the continuance of modern civilization.

This neglect shows up in all sorts of ways:  in the cultural attitudes that tell young people to become a doctor, lawyer, or other highly-paid professional, or else abandon all hope for a decent respectable career and marriage; in the absurdly skewed pay scales that are tending to turn the U. S. into a culture of a small elite reigning over poorly-paid "unwashed masses"; and in the fading of a small-d democratic attitude that recognizes the vital contributions of even the lowliest and lowest-paid workers in an organization or an economy as being just as important as the CEO, but in a different way. 

So while I congratulate Captain Shults for her heroic actions to land Flight 1380, I hope that the nameless technicians, inspectors, bureaucrats, and others whose achievement it has been to make air transport as safe as it is will redouble their efforts to keep anything like the fan-blade accident from happening again.  And if they do their jobs well, maybe I won't have a chance to write about another commercial U. S. airline fatality until I'm too old to care.

Sources:  I referred to a BBC report on the Flight 1380 accident carried on the news organization's website on Apr. 21, 2018 at  I also referred to a report of the 2016 fan-blade accident at the NTSB website, a New Scientist article that appeared on Nov. 5, 2010 at, and the Wikipedia article "United Airlines Flight 232" about the 1989 turbine-blade accident.  The article "After Innovation, Turn to Maintenance" by Andrew L. Russell and Lee Vinsel appeared in the January 2018 issue of Technology and Culture, pp. 1-25.

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