Engineering Ethics Blog: 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.



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