Aviation knowledge

I do. (I know: I’m a card-carrying member of the nerd club.) Here’s what Mr. Isbell said about writing papers: “You can have the best grammar and supporting evidence in the world, but no one will care if you don’t include the ‘so what.’ You always have to answer the question, ‘Why is this relevant?’” In aviation, students are hit with such an onslaught of new information that it’s often hard to pause and ask how they would apply the new knowledge to real-life flying. But you must. Two reasons, really: Checkrides are scenario-based questioning. Rote memorization won’t cut it. Second, and more important, flying calls for solid, correlation-level knowledge. You may be several thousand feet in the air when the engine starts running rough. Your stress level is going to skyrocket if all you can remember is your LHAND acronym (Lycoming, horizontally opposed…I’m sure you can recite the rest). As an FAA-designated pilot examiner, I’ve often seen that applicants cannot apply their knowledge to either real-life scenario type questions or the actual flying portion in the following ways:

Density altitude.

What is it? Why does it matter? Here is the answer I often get: “Density altitude is pressure altitude corrected for nonstandard temperature.” Long pause while I wait for my applicant to get to the good stuff. If no elaboration is forthcoming, I’ll ask some follow-up questions. “Yes, but why should pilots care if density altitude is 5,000 feet today? Also, what causes density altitude to increase like that?” The answer is that higher density altitude causes worse aircraft performance. The famous three Hs are bad for performance: Hot. High. Humid. If you don’t have this level of working knowledge, you may take off on your favorite grass strip that’s been fine all winter only to discover that your fully loaded aircraft cannot clear the trees in the middle of summer.

Weight and balance.

If you have been simply plugging numbers into your flight school’s weight and balance spreadsheet, but you have no idea where the numbers come from or what the calculated answers say about your performance, you don’t have the complete picture. For example, basic empty weight (BEW). Where does it come from? Applicants often answer, “the pilot’s operating handbook.” When I ask them to show me, they will pull out their 1984 Cessna POH and find the original BEW. Friends, that number has not been accurate in almost 40 years. This aircraft may have had nine avionics upgrades and three engine changes. Please, locate the actual current BEW from the weight and balance sheet signed by a mechanic. Also, understand that if you end up with takeoff numbers that are close to the maximum takeoff weight and a center of gravity that is all the way aft, you are flying an airplane that will be very different than one that is lightly loaded with nothing in the back seat.

Maneuvering speed.

The common memorized checkride answer is, “It’s 99 knots, the speed above which we will stall before we have structural damage.” That same applicant will take me up for the flight portion in a lightly loaded airplane and perform a steep turn, letting the airplane accelerate well past 99 knots. A complete picture of the knowledge here would include the fact that maneuvering speed shifts with weight. A lighter aircraft has a lower maneuvering speed. Also, maneuvering speed only protects against a single control surface deflection. If you are way too fast, with a steep bank, an aggressive upward pull on the yoke, and no rudder coordination, we’re looking at the possibility of an accelerated stall, a spin, or structural damage. Yikes.

Systems knowledge.

Years ago, I was attending recurrent training for a Beechjet I was flying, and the systems instructor said something I’ve never forgotten: “When you are learning about your airplane, you need to find out how the mouse gets the cheese. We don’t care if it’s 50-day, barrel-aged blue cheese, we just want to know how the mouse finds his way”. To use the engine roughness illustration from earlier, we don’t care how many cubic inches of displacement your engine has or how many inches long the propeller is. We want to know, if that prop stops spinning, how do we make it go again? There are a few things in your control as far as the engine is concerned, and most of them have to do with fuel or ignition. So, pull the carb heat on, check the fuel selector and mixture positions. Make sure you haven’t accidentally turned the magnetos off, and run through other memory items. Having a working-level knowledge of these simple concepts will go a long way toward keeping you safe.

Remember, whether you are a student preparing for your checkride or an instructor helping to prepare that student, it’s not enough to simply memorize the information. Ask yourself, how is this relevant? Where can I use this?