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Monday, December 23, 2013

Back to the Basics

Recently I flew with a pilot, commercially certificated with a couple thousand hours, that has been exclusively flying his airplane, a Cessna 182, for the past three years. Admirably, he decided to pursue a tailwheel endorsement to improve his skills. The Decathlon is not a particularly difficult airplane to fly; but certainly different than a C182. It's not as stable, bordering on neutral dynamic stability and has more control authority (inputs produce instant results about all three axis). The Cessna is robust, stable airplane with comparatively slower response to control inputs and its dihedral tends to return the airplane to unbanked flight with little or no input (depending on the upset). So clearly these two airplanes require the pilot to operate each differently. The exclusivity with which this pilot operated his airplane probably makes him a pretty good C182 driver, but when faced with the change to the Decathlon, caused some grief. Seeing this pilot's troubles, primarily with airspeed control (you know, the stabilized approach yields a good landing -- some caveats apply), I stressed airspeed control. What was surprising is this fellow was unable to capture airspeed. Hmm, I was momentarily dumbfounded (I find this more and more as I get older). How can a 2000+ hour pilot not capture and maintain airspeed? It's simple, the same way a beginning, low time student pilot does--failure to attitude fly the airplane. You probably remember this or some rendition of this from your initial instruction: Attitude + power = performance. But if you replace attitude with airspeed (which is performance) you get Mr. Toad's Wild Ride, that is, the pilot tries to capture airspeed by exclusively watching airspeed. We know there's a lag in what that instrument tells us, so to get a more instantaneous response, we increase the pitch input, but we then overshoot the target, and provide input in the other direction, resulting in pilot induced oscillation. The fix is simple, go back to the rudimentary "fly the windshield," making small corrections out front, and crosscheck the airspeed indicator. Twenty minutes of constant airspeed descents from altitude fixed the problem. In this case, taking a few steps backward, back to the basics, moved us closer to the goal. I hope to see you out at the airport!

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