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.



    My Favorite Dog photo, – January 2009


    I drank too much coffee and it is now 3:35 am, so I am just combing through photos to finish a couple of technical posts on Instrumentation and Human factors. I came across this photo from Super bowl Sunday 2009. It is one of my favorites:


    Above ScoobE’s first plane flight. He, Grace and I are aloft just before sunset in Grace’s 1946 Taylorcraft. We had only had him a short while then, and had not learned how to keep up with how fast his hair grows. It looks like a paw, but that is actually an ear draped over Grace’s wrist. His front paws are on her elbow. Out the window you can see a swath of Northern Florida. This was the only flight ScoobE did without hearing protection. Since then he has his own set of Mutt-Muffs. I was concerned that he might panic in the flight, but as it turned out he fell asleep in about 5 minutes and only woke up on final.-ww.

    Ted Simon, Jupiter’s Travels -book


    Going back for a moment to books, I want to bring this one up also. It was highly influential in changing my perspective and definition of adventure. I read it when I was 17 years old in the fall of 1980.

    Most books you cannot remember how you heard about them, certainly not 34 years later, but this one I can. On a weeknight, I was driving my 1965 Buick Skylark around my home town in northern NJ. It was late, and no one was out at any of the usual haunts. The car only had an AM radio, the kind that said B-U-I-C-K on the five push button selectors (If you are less than 50 years old I will explain that at a college) I was listening to WABC, a New York City AM Clear Channel. around midnight they went over to an interview show. Their guest was an English motorcyclist who had spent 4 years riding a 500 Triumph around the world solo. He was a captivating conversationalist. I drove up to Washington Rock and listened to the whole interview, which ran until 3am.



    When you are 17, and you get a license, high school is coming to an end, and your horizons are expanding, you start looking for some path to follow to your next place in life. For most kids in my town, the single word ‘college’ sufficed as planning enough, and they contentedly went on their way.  Although I later spent many years in college, at the time I  encountered this book college looked more like a yoke and harness than an adventure.

    Ted Simon’s interview and book opened my eyes to just how full of adventure the world could be. In his perspective, nothing was predefined, you were only limited by what you were willing to try. It particularly caught my attention that Simon had hardly ridden a bike before, and he openly expressed self doubt about every aspect of the trip. He explained that if you knew you could make it before you left, than it wasn’t an adventure at all.

    His book taught all kinds of lessons about patience, about the difference between being a tourist and a traveler, about how few people who have been abroad can say they have dined in the home of a native.

    It isn’t coincidental to me that this book, Zen and the art of Motorcycle maintenance, and Shop craft all have an element of motorcycles in them. Before I came to aviation, motorcycles were my machines of adventure. This is a common thread going back to Lindbergh and Curtiss.  Jupiter’s travels was my introduction to external travel. The following year I read Zen, and it was a guide to traveling in your own thoughts and perspectives. Shop Craft is a very interesting book that bridges the two together, speaking of how the physical work affects the cognitive perspective of the world.

    Before Christmas I spent an hour looking at a few photos of me as a 16-19 year old that I found in the bottom of a box of papers.  The connection between myself and the person in the photos seemed long and distant.  I looked closely, but I couldn’t really say what thoughts the person in the photo possessed.  I like to ask him to remind me, to establish more of a connection that the fact that 10,000 days later I find myself inhabiting his body. I would like to remember what he cared bout, was planning, was doubtful of, and hoped for, but I can’t. Almost all of it is gone. Except for one small sliver of an evening, where he listened to a guy from England explain that the world was completely accessible to anyone who would just wander out there and live in it. Those hours I remember clear as a bell. -ww

    Don Pietenpol Passes, 1/8/14


    I received a short note from Minnesota 750/Corvair builder Dave Griggs saying that Don Pietenpol had passed from this Earth.  Don was an aviator in his own right, but he has done tremendous work making his father’s (Bernard Pietenpol) designs and perspective available to new generations of experimental aircraft builders.



    Don Pietenpol had a direct influence on my personal path in aviation, and I am very thankful for it. In 1989 I was just beginning 5 years at Embry-Riddle. Composite construction, computers and Reagan era defense contracting were reaching a fever pitch. Every single student I knew, every instructor and the whole program was focused on the cutting edges of military, space and defense projects. Almost every freshman could tell you which high end project he was focusing his education on; stealth , GE-90 engines, Finite Element analysis programing, and C4 systems all had legions of new converts, patron saints in the faculty and research money from administration. In this storm of high tech, I found myself fascinated with the “past.” I spent my time in the huge 3-story campus library reading about planes and men from the 1930s.  I was 7 or 8 years older than most freshmen and was at a different place in life, but still I was smart enough not to say much of anything to anyone about my divergent interest from the crowd.  It was a tough school, and you had to effectively work in lab and research groups to succeed.  Openly telling others that you were interested in planes built of wood was tantamount to being mentally ill.

    I cannot judge my peers of 1989 harshly. Although I loved the traditional aviation I devoured in my free hours, I had a nagging self doubt about its value as a path. Part of my brain told me that I was taking a small exit ramp off a highway that was going great places and the travelers would be handsomely rewarded for making it to the intended destination. I kept coming back to the idea that there probably was an engineer who quit the Apollo program in 1965 to chase a barnstorming dream and regretted it the rest of his life.

    Following my heart, I quietly sent a $50 postal money order to a guy named Don Pietenpol to purchase a set of his father’s drawings. I still distinctly remember walking to my mailbox, #5601, on a Friday afternoon after classes and finding the plans tucked into the box. I didn’t wait to bicycle the 2 miles back to the house, I sat in the empty cafeteria and spread them out on a table.

    With my money order I had sent a short note saying that I was interested in things my fellow students were not. It was the kind of thing that you would never include in a regular business order, but this was to Bernard’s son, and frankly, I just wanted to share my secret with someone whether they understood or not, just a safe ear, even if it was a deaf one.

    Don Pietenpol was not deaf to such thoughts. With my plans came a short 120 word note, a letter that is hard to overstate the impact of. He said that even in his father’s time there were men who followed fortune into military or airline work, and his father could have done this, but willfully chose not to. He said that aviation always needed a small group of people who were going to preserve and develop flight in its purest forms, and to these people it should not matter what the crowd would do.

    I have this letter carefully saved. I look at it from time to time. There are days when little is going smoothly and I cannot discern any positive effect from my efforts. Like everyone else, I indulge myself a few thoughts, wondering about other paths not taken. Then I come back to a short letter written by a 59-year-old in Minnesota  to a 26-year-old College student he would never meet in person. Simply an observation that paths that make sense in your mind should be subservient to those that dwell in your heart.


    Below is Donald’s obituary:


    Donald Dale Pietenpol, of Rochester, Minn., passed away Wednesday, Jan. 8, 2014, (on his 84th birthday) of cancer at Vanderbilt University Medical Center in Nashville, Tenn.

    Donald was a loving husband, father, grandfather and friend; a Korean War veteran who served in the U.S. Air Force; an engineer at IBM; ham radio operator (K0DFZ); a pilot; a builder of experimental planes; aviation enthusiast; and member of the Quiet Birdmen.

    He especially enjoyed spending time with his grandchildren.

    Donald was born in Wykoff on Jan. 8, 1930, to Bernard and Edna (Krueger) Pietenpol. He married Olive Robinson on Oct. 31, 1959.

    Donald is survived by his wife of 54 years, Olive; three children, Andrew Pietenpol (Joyce Larson), of Cottage Grove, Donna Pietenpol, of Katy, Texas, and Jennifer Pietenpol (Ian Wattenmaker), of Nashville, Tenn.; and six grandchildren, Alexander Panetti, of Katy, Texas, Brittany Panetti, of Katy, Texas, Collin Panetti, of Katy, Texas, Gavin Higgins, of Nashville, Tenn., Caroline Wattenmaker, of Waterford, Va., and Annie Wattenmaker of Waterford, Va.

    Donald was preceded in death by his parents and brother, Kermit.

    A memorial celebration of his life and graveside service will be planned later this spring. The family requests that memorials be directed to the Vanderbilt-Ingram Cancer Center in Nashville, Tenn., to support cancer research discoveries.

    For more Pietenpol history go to the link below:


    76F in FL, Grace at the wheel of a Deuce and a half, grateful


    Just to remind people that snow doesn’t have to happen, a few photos from our airpark taken today, January 11th. It was sunny and 76 degrees in Northern Florida. Brothers Jim and Paul, both vets who donate huge amounts of time to our local military museum, drove over in two of their personal vehicles, a 1967 M-35 and a 1963 M-37. We had a bit of fun driving them around the airport.

    To our friends in Minnesota, Yes, I am rubbing it in a bit about the weather. Before you know it, the flying season will migrate back up north and we will be into a new year of aviation. Make your plans now.

    For us down here, another month or so of this and it will be snake season again. If you are cold right now and need a reminder of why you don’t live in the tropics, click on this link:

    Fun with Agkistrodon Piscivorus and Vern’s Aero-Trike

    or this one:

    Let It Not Rain




    Above, Grace behind the wheel of the M-35. In slang terms, this is a “Deuce and a Half” because it is a 2.5 ton truck. (That is the off road rating, it carries twice that on road.) It is 10 wheel drive and sports a “Multi-fuel” straight six turbo diesel made by White. These engines burn any kind of fuel: Diesel, kerosene, jet fuel, even gasoline diluted with old motor oil.



    Above, I cut a lap around the airpark in the M-37. Technically it is a “3/4 ton truck” but most people know them as a weapons carrier.



    Grace and Scoob E exiting the M-37.



    Above, friends hanging out. On the left, Corvair/Panther builder Paul Salter, whom many people have met at Corvair Colleges and Oshkosh. Jim’s son, Jim, Paul, and our friend Alex, whom you read about in the story: Sunday, a long day at the airport.



    It is fun to live in a place where it is normal for friends to stop by with an M-37.  When Paul drove over, Grace and Scoob E were relaxing at the side yard in a hammock. Grace’s attire should tell you I am not kidding about today’s weather. Down here the leaves come off the trees the first week of December, but the green buds come out by the end of February. Behind Grace is the little creek that runs past our place. To clarify for people up north, this creek is filled with something called water, which is made of a liquid form of ice and snow. -ww.

    Note from Grace: “The book pictured above is one I can highly recommend, American Sniper by Chris Kyle, the Navy SEAL known as the most lethal sniper in American military history. After the military hardware rolled out of our airpark to beat the thunderstorm rolling in, I couldn’t help but think about all the troops they’d carried into godforsaken places to ensure all of us here at home had the freedom to read what we wanted any given day. And how many troops never made it home. Or returned home broken physically or mentally.

    A few years ago during my parents’ 50th anniversary cruise around the Caribbean, while my parents took the bus tour I spent the afternoon snorkeling and drinking rum punch with a lovely couple from Michigan. He told me he’d retired from the police force there, but it didn’t take a detective to figure out he was a soldier before that. I asked him where he served, and he said Vietnam. I thanked him for serving our country and he told me I was the only person ever who had thanked him for his service to our country. Then he cried. And I cried. And his wife was dumbstruck for a moment, then held him tight. She had never seen him cry. I apologized on behalf of those Americans either too oblivious, ungrateful, shy or afraid of being corny to express their gratitude. Nothing a little more rum punch couldn’t fix that afternoon, but that’s never a real solution. Too many people from the top of our government down to the lowliest civilians don’t treat veterans returning from the war on terror today much better than they did in the Vietnam era. I don’t know how to fix that other than to continue to thank our military for their service to our country, and encourage all of you to do the same.”

    50 days until CC#28, and a look at CC#22


    Here is another encouragement to get in gear and sign up for our Texas College in 50 days. Below I have links to a number of stories from our last Texas event, CC#22 two years ago. One of the links is  “College tech,” a group of photos and a short film that few builders have seen.

    Above, with me is Blaine Schwartz of  Texas, a Zenith 750 builder. His engine ran at CC#22, and his plane in nearly finished now.


    Builders who would like to get all the details on how to sign up for CC#28 can click on this link:

    53 Days until Corvair College #28.


    For those who still need a little convincing, let me say that we have 40 builders signed up already, and we are space limited at this event, so if you wait too long, you will not be happy. Kevin and Shelley, our local hosts, are already sending out information briefs to all the builders who have already signed up. These builders are prepping to have an outstanding event and a productive season. To get in on this you must act.


    Click on this link: College Tech . It has lots of engine and builder photos from CC#22.


    Above, Craig Anderson of South Dakota with his Weseman bearing equipped 2,850 cc Corvair in process at CC#22. His engine is now running on the front end of his restored Stits SA-7 Skycoupe. This is actually the same airframe that was our 2002-2003 company testbed shown in this link: 2,700cc-Skycoupe-2002 Photos. Craig has done an outstanding job of overhauling and upgrading the old bird, and I look forward to seeing it airborne again.


    To get a look at the detailed story of Blaine Schwartz’s 2,850 running, click on this link: Schwartz
    Engine Runs at CC #22


    To get a look at Becky Shipman’s 2,700 running at CC#22 click on this link: Shipman
    Engine at CC#22


    To make sure that I can write a story about your engine running, click on this link:



    Zen and The Art of Motorcycle Maintenance – ( book )


    In letters, several people mentioned the connection to the 1974 book  Zen and The Art of Motorcycle Maintenance by Robert Pirsig. I first read it in 1981,when it was assigned to a friend in college, and I have returned to read it again every 10 years or so. It is different each time; obviously the book never changes, just my perspective does. The novel is something of a yardstick against my thoughts.

    The book is very much like The Ugly American in the sense that both are endlessly used as a reference by people who have never read, nor are even acquainted with the contents. Pirsig stated outright that the book has nothing to do with Buddhism or motorcycles; it is a vigorous work of philosophy, specifically targeting the value of quality. It is widely respected as an intellectual and artistic masterpiece.

    It says something about professional critics that the manuscript was rejected for publication 121 times. It has since sold 5 million copies. It is a difficult read. Pirisg has a 170 IQ, a number that happens in only 1 out of 150,000 people. He patiently explains, but does not dumb down the subject. The storyline is roughly autobiographical, and he leads you through his descent into madness and the cruelty of suffering that fate in the 1960s. The immediate setting of the narrative is on a motorcycle trip with his son and two friends in the Western U.S.  He is revisiting both the questions that drove him and the places he lived in his former life, the time before he was ill.  He rides with his young son, whom he fears may have the same path ahead of him.

    The book’s success was not a harbinger of peace in Pirsig’s Life. His son was murdered in 1979 and Pirsig lived most of his life in seclusion, writing only one other book. He is 85 years old now and lives quietly in Maine. This strikes me as a contrast to how much light and illumination he put into countless lives of others, almost all of this for people he would never meet. -ww.

    Robert Pirsig on a Motorcycle

    Above, Robert Pirsig and his son Chris on the trip that was reflected in the narrative. I did not see this photo until 20 years after I first read the book. Pirsig is a powerful writer, and the setting he vividly described became imprinted in my mind. When I first saw the photo I had a very strong sense that I had seen the exact spot before, although I have never been to Montana. I have returned to this photo many times and thought about how his son only lived 10 more years.