Instrumentation: Perspective on Risk Management


The letter at the bottom below is from Ken Pavlou, Who’s 601 XL has a dual Dynon display. It is some clear thoughts on how instruments are just a part of an experimental aircraft’s flight capability, I think it is worth considering in detail before making a decision on which level and type of instrumentation will be in your plane.


In the paragraph immediately below is a link to a story about the crash of Air France 447 several years ago. It was sent to me by builder Terry Hand, who has the perspective of being a former USMC flight instructor and having also flown a global career with a major airline. He has logged more than 20,000 hrs, but critically his experience spans the change discussed in detail in the article.


Because the black box of 447 was recovered from the bottom of the Atlantic 2 years later, a great level of detail is known about the last 5 minutes in the cockpit. I have read countless accident reports, and it breeds a certain dispassion, but this article is different, I read it 3am. I had nightmares the rest of the night.


What does this have to do with light planes? Easy: earlier this year we had CH-750 pilot with 60hr on his plane fly it into the ground by the exact same method that the Air France crew used to kill themselves. To avoid repeating this it is worth studying and discussing.


The pilot took off with his first passenger and climbed away from the runway. At several hundred feet the plane began to sink and would not respond to back stick and climb. Unaware, he responded in the exact same manner as they did to excessive angle of attack, by pulling the stick back and holding it there, not understanding that the planes sink rate was caused by slow airspeed and massive drag, not a reduction of power. He and his passenger lived. Put them in most other light planes, with sharper stall behavior, a Cub or a C-150, and they die.


The builder initially told everyone he has a power loss that allowed him to sink into the ground, but after reflecting on the behavior of the controls he quietly realized that he had held the plane at an excessive AOA and let it sink all the way into the ground. contrary to what many people were told, the follow-up tear down  and test run on the engine showed that there was nothing wrong with it, but it was too late for most people to learn that, what they ‘learned’ instead was ‘Corvair engines are unreliable.’


What can be done about this? Training. Start by reading this article on departure stalls:



“Here is a link to an interesting article on the Air France 447 crash. Note the writer’s last name. (He is the son of the man who wrote Stick and Rudder-ww.)

I thought you might find this an interesting discussion, based upon your studies at ERAU. -Terry”




“William,  I love flying with my glass panel, but the truth is 99% of my flying to date was done behind a standard six pack of instruments. The bottom line is they work and they work reliably. The reliable part is what interests me more than anything. Glass cockpits can be reliable and often times reduce cockpit workload significantly.

The caveat is you have to know how to use the equipment and understand what they are telling you. I’ve been witness to pilots increasing their risk flying behind a glass panel, even in perfect VFR conditions, simply because they didn’t take the time to master the equipment which led to a lot of fumbling around and taking concentration away from the primary task of flying the airplane. No matter how sophisticated an instrument panel is, it will never improve basic stick and rudder skills, turn you in to an IFR pilot, or replace prudent judgment.

I spent countless hours sitting in my plane after I built my panel with all the instruments on together with their operation manuals making airplane noises and familiarizing myself with all the knobs, buttons and features of my equipment. An important part of knowing your equipment is it’s failure modes. Just like a simple mechanical altimeter can read high, low, or level depending on different pitot-static faults, glass panels can at times produce inaccurate information. For example, On my flight back from Barnwell my Dynon EMS indicated my oil pressure was high. It would blip from the usual 45 PSI to 55 or 60 and back. At first I thought maybe my regulator spring and piston were getting stuck. As a precaution I removed the spring and piston at my next fuel stop. Both items were in perfect condition and functioned as they should. The problem turned out to be some electrical contact corrosion on my oil pressure sending unit.

The point is that computers can’t take the place of critical thinking and decision making. Whether the data they report is valid and how its used is really up to the organic computer embedded inside our heads. -Ken”



Grace took the above photo in Ken’s Cockpit at CC#31, before taking off a few minutes after sunset for a local flight.

One Reply to “Instrumentation: Perspective on Risk Management”

  1. A glass cockpit and an “Un-Natural Control System” helps a lot to bring about such a chaotic situation but it can be done in a conventional cockpit as well, all you need is to commit to a mind set about what the problem is and you will ignore all evidence to the contrary. The best case in point was a National Airlines 727 flight back in the late 70’s (I think). It was a repositioning flight so only cockpit and cabin crew were on-board and that it did not involve a large loss of life keeps it from being more well known. During the running of the pre-takeoff checklists there was an interuption and the pitot heat was left off. After depature the aircraft climbed into clouds and the pitot tubes iced up, showing increasingly wrong indications of high airspeed as they continued to climb. The captain got into the mindset that the airspeed indications were correct even though they were wildly out of the reasonable and interpreted stall buffet as mach overspeed buffet. This was in a nose high climbing condition at high altitude which was really an impossibility. Just as with the Airbus they rode the resulting stall all the way to the ground and never really realized what was really going wrong.

    As a side note the automated warning systems on most of these sophisticated glass cockpits have shown a tendancy to make critical situations worse. They have been known to produce a long list of indications that just add greater confusion to the situation as the crew tries to make sense of what is going on. That was all too true in a V-22 crash after an engine fire and lead to a major redesign of the system to try to correct the system so it would not display so much low priority information and stick to the high priority stuff.

    As the adage goes, “To err is human but to really screw things up you need a computer” still “Where there is a Will there is a Way”.

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