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On the Curve

By Gene Benson

While working in aviation safety at Transport Canada in 1993, Gordon Dupont developed the concept of the “Dirty Dozen.” This was a list of twelve factors that often lead to human error. At the time of its inception, Mr. Dupont directed his list toward human errors in the aviation maintenance field. His concept has since been applied to many other areas, both within and outside of aviation.

One of Mr. Dupont’s twelve items is complacency. It can be described as a feeling of contentment or self-satisfaction, often combined with a lack of awareness of potential dangers. Complacency often arises when conducting routine activities that have become habitual and which may be viewed by the individual as unchallenging and without risk. Familiarity with the tasks can cause a general relaxation of vigilance. This can result in important signals being missed, with the individual only seeing what is expected. Becoming lax about performing the preflight inspection is a common example. Another is becoming less concerned about flying in forecast icing conditions after numerous flights in similar conditions without encountering significant icing.

Applying this concept to pilots, my own observations and experiences have led me to believe that complacency is not a linear function but rather a curvilinear one. We do not start out as a new pilot completely free of complacency, but then become more and more complacent along a line with a given slope. I think the level of complacency more often follows a curve. Our humanness causes us to become ever more complacent regarding a given task. Then a minor event often serves as a reminder and a sharp decrease in the level of complacency immediately follows. The event could be a personal experience with a real, but minor problem or it could be as simple as reading an article about an accident.

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The danger lies in encountering an event that is more serious than a minor event serving as a reminder. The event is likely to end in an accident.


I have experienced this up close and personal. Fortunately, I am still around to write about it. I never had an accident, but at least two of my reminder events could have ended badly. I once failed to find a bird’s nest in the left engine cowling of a Beech Duchess during the preflight inspection. Just prior to taking the active runway, one final check for traffic on final revealed a trace of smoke coming from the cowling. Had I not noticed the smoke and made the takeoff, I probably would have had an engine fire during initial climb out. In another case, after many hundreds of hours flying airplanes without any ice protection in the Northeast during winter, I began to believe that structural icing was not much of a threat. Then one day, climbing out to get above a cloud layer in a Piper Seneca I, my rate of climb became negative. I was able to return to my departure airport, but just barely. I could not even maintain minimum vectoring altitude and I was below the glideslope for most of the approach. I was able to extend the landing gear just a few seconds before touchdown.


Fighting complacency is not easy since it is part of our humanness, but we can mount an effective defense. One valuable tool is to have and use a detailed set of checklists for each phase of flight. We must promise ourselves that we will always use the appropriate checklists and never allow anything to prevent that. Another item in our toolbox should be a personal minimums checklist which has been created well before the day of flight. Still another tool is the Flight Risk Assessment Tool, or FRAT. All these tools, when used correctly, force us to follow procedures and prevent us from skipping steps or otherwise falling prey to our humanness.


One final mitigation method against the risk of complacency is to approach every flight as if it was a checkride. I have tried to do that based on advice I received from an FAA inspector after a Part 135 checkride in the late 1970s. I have deviated a few times, but I know that following that advice has saved me from bad a outcome on more than one occasion.