Risk Management – Human factors


At the bottom of this story is a commentary I wrote on human factors several years ago. It was prompted by an internet discussion where several builders were proposing complex arrangements for engine controls and questioning the value of the Nason switch we recommend for engines with electric fuel pumps.

The recommendations we make are in accordance with the things I know about human factors in general aviation. My degree from Embry-Riddle is in Professional Aeronautics, which is basically accident investigation. The classes were a broad variety of subjects in aerodynamics, performance, meteorology, statistics, etc., but we spent a lot of time studying human factors. Most people have heard the saying “Guns don’t kill people, people kill people.” If you had seen all the accident reports and investigations we studied, you would understand my variation “Planes don’t crash, people crash planes.”

Any discussion of risk in GA aircraft that excludes human factors, or even how humans react to an equipment failure is not worth having. Yet, most of the conversations about risk management in experimental aircraft all get focused on reliability of the mechanical systems, as if the people in the plane were never a factor in any homebuilt accident. Know this: Most accidents in homebuilt aircraft are caused by people willfully doing things that any objective observer, even a novice one, could pre-identify as poor decision making.

Lets say you are new to home building, or maybe even aviation in general. You are concerned about safety. One of the most unsettling things to you is reading about accidents, or equipment failures that happened to pilots with 20,000 hours or builders with PhD’s in engineering. If experienced people like that have had problems, what possible hope does a green new guy without experience or specific education have?

Actually, the new guy can be at far lower risk. I have said plenty of times that managing risk is about exercising judgment, period. Experience and training are only a defense if they are combined with exercising good judgment. without the latter,  Experience and training only allows the person without judgment to push the envelope further or flirt with how much they can get away with.

The is an age old saying that a new pilot starts off with a full bag of luck and an empty bag of experience, and his has to fill the experience bag before he drains the luck bag. Take this story as 100% bullshit entertainment for non-aviators. In reality, every pilot must be trained in judgment (“Decision making”), and then exercise it while flying as PIC within the limits of his skills, as the day, plane and situation present themselves.

Stay away from any person in aviation who actually believes in ‘luck.’ They have abdicated from the responsibility for taking care of their lives.  Understand, even though they ‘sent in their resignation letter’, Physics, Gravity and Chemistry don’t accept these resignations, and they still hold him fully responsible. The evidence that fools present for the existence of luck is vague and anticdototal at best.  Hard, proven and factual evidence for the existence of Physics, Gravity and Chemistry can be found at any crash site. The new statistics that used to be people didn’t run out of luck. Most of them didn’t run out of experience or training either. Most of them just decided that it ‘would be alright’ if they tried something that was poor judgment.

The most important thing for a new guy to understand is that it is called “Human Factors”, and not called “random chance.” If accidents happened to people at random like the way people win lottery tickets, the only thing for accident investigators to do would be to divide the total hours flown by the number of accidents, and then brief every single pilot that they would face the same rate. The very premise of accident investigation is that they are inherently preventable. They each have their own probable cause, and humans, not luck, almost always played a role. Understand that role, don’t repeat it yourself, fly within your personal envelope, and you are practicing effective risk management. -ww.


Our 601XL on final to arrive at Oshkosh 2004.   The airport, city and Lake Winnebago can be seen in the distance in the photo above. The layout of the controls, including the starter button right above the throttle and the A/B ignition switch above the VSI reflect things I know about Human Factors.  We set up the 601XL with 2 fuel pumps and 2 ignitions. If the engine had any kind of a hiccup, the procedure is to throw the A/B switch, go full rich and apply carb heat, period. If it is going to get better, that will take care of it.  Pilots who thought that lots more switches would allow them to analyze the instruments in a hiccup, decide if it was fuel pressure or ignition related, then select a different switch combination are kidding themselves.  The first thing that disappears in an emergency for a 200 hour pilot is his analytical skills. He is far better off with simple procedure and practice.


Above are 13 Nason switches. These are Part No. SM-2C-5F. In our arrangement, this is the switch that automatically turns off the electric fuel pump when the plane is on the primary ignition but it has no oil pressure. In an accident, the pilot does not have to turn the master off, or even be conscious, this part does the job. Yet, I have read many internet Chuck Yeagers say that if they were about to have a forced landing they would always remember to turn the pump/master off. In 25 years of flying I have been the first person at the scene of four crashes, and the master was on in all four. Human factors training tells you this is an important system.


    Think human factors applies to just new green pilots? It doesn’t. I have worked on both Mig-15’s and 17’s. Above is the cockpit of a 15. It is not an easy nor forgiving plane to fly, and their pilots had to have significant training just to survive the plane, far less combat. Look at the panel and see the vertical white stripe; When this plane enters a spin, the procedure is to have the pilot jam the stick forward and align it with the offset white stripe. Even professional pilots benefit from the simplification of procedures. People who like to complicate things rarely are willing to acknowledge any possibility that such a design and their own lack of training under pressure is the actual weak link in the system.

    (* note that soviet attitude gyro colors are reversed from western ones, a very serious potential human factor issue.)


    Below, the 2008 comments:

    Touching on human factors in aircraft; It is a big topic in aviation, a sub  discipline in which you can get a Ph.D.. In our application it boils down to  this: The least reliable part in most well built planes is the pilot. The funny  thing about saying this is people who don’t fly are offended or disillusioned to  hear this, people who do fly for fun all have a personal memory or two that  keeps them from arguing the point, and people who work in aviation know that  this is absolutely true.

    Before anyone is too offended, let me say that I include myself in the  category of least reliable parts. I have been around enough great pilots to know I am not one. Yes, I  can fly stick and rudder planes just fine, and can do so without working  instruments etc. But three times in the last 12 years I have been in a  plane that was not functioning correctly. At this point, most people, myself  included, will fall back on their most basic training and procedures. The saying is that “Your skills will not rise to meet the challenge, they will sink to the level of your training and practice.”

    If the training  was good and the procedures are simple, good. If you have zero experience with  being PIC, it is easy to daydream that under pressure you will have all the analysis skills of  a B-36 flight engineer, but you won’t, and if you set your plane up in a way  that requires multistep procedures and cross checking instruments and decision  paths, you will probably even forget to fly the plane.

    I know pilots, like Dan Weseman,  Gus Warren,  Anthony Hanson and our friend ‘Frosty’ who are immune to stress in the  air. Most of us are in a different category. Safety lies in honesty, and honesty requires each of us  be truthful when evaluating our skills and laying out or planes for the  pilots we can train to be rather than the ones people daydream they  are.

    Having been in a stressful situation, it is very hard, once safely  back on terra firma, to continue to believe that you are in the ‘ice water circulatory system club’, if you have just seen your skills shrink under real pressure. I  am OK with this revelation, and I use it to my advantage.*(see  below)

    Because the Corvair started out life as a car engine, a lot of people  with a good background in cars feel like they know a lot about how a plane with  a Corvair engine should be arranged. Some things do translate, but if I had to  name the single facet of aviation that car people fail to understand, it is how  little of their troubleshooting and analysis skills will function when the fan  stops. For this reason, the layout  should be simple, and the emergency procedures well practiced.


    *Risk Hierarchy of piloting:


    Most Safe: Daydreamer, never finishes, never flies, dies at  keyboard choking on potato chip. Not an aviation statistic.

    Moderate Risk: OK training, self illusions never challenged

    High Risk: OK training, finds way out of a few jams, thinks he is in ice  water club, keeps taking more risks.  Often incorrectly eulogized as a member of ice water  club.

    Acceptable Risk: Good training, realistic self evaluation, practices  emergency procedures, OK with getting autograph of guy in ice water club.

    Very Low Risk: Card carrying member of ice water club.



    One Reply to “Risk Management – Human factors”

    1. believe me, there really are some lucky people out there! pilot I worked for landed on a dirt strip with full tanks, saw there was nobody to meet him;applied full power to take off and flew straight into the trees at the end of the runway.Fuel everywhere. no fire, walked away with a broken collar bone.interesting thing though, we checked his bio-rythyms- all three were on the lowest point.

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