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Stalls' nemesis still strong after 70 yearsStalls' nemesis still strong after 70 years

In July, Flight School Business noted that about 100 accidents every year result from inadvertent stalls in the traffic pattern. Unintended stalls in other kinds of maneuvers—low-altitude buzzing, instrument approaches, and simulated engine-outs, among others—lead to a few dozen more. As a group, these accidents are about one-third more likely to be fatal than general aviation accidents overall, but that figure masks considerable diversity: Fatalities are rare in stalls on short final or just after takeoff, while those resulting from base-to-final skids or low-altitude buzz jobs are lethal almost three-quarters of the time. If you’re already close to the ground when the nose drops, the impact tends to be a lot gentler than if you’ve got a couple of hundred feet in which to pick up speed.

In a recent online discussion, one veteran pilot pointed out that the aerodynamics of stalls have been well understood and well-explained for decades. In particular, he drew attention to Wolfgang Langewiesche’s classic text Stick and Rudder, which was first published almost 70 years ago and which still provides one of the best explanations of angle of attack, downwash, lift, and—yes—stalls ever written. The language seems a little quaint by contemporary standards, but that’s actually one of the book’s virtues: Unlike modern authors, Langewiesche takes the time to really make his points, hitting them from a succession of different angles and shooting down common misconceptions one after another. Even his more unconventional figures of speech are deliberate and purposeful. Through most of the book, for example, he refers to the airplane’s elevator as “flippers” to make the point that it doesn’t “elevate” the airplane, but merely flips the nose up and down. The reader who still doesn’t get it by the end of Langewiesche’s exposition probably isn’t going to get it.

And the accident data provide plenty of evidence that too many pilots don’t get it, despite having learned enough of the formalities to pass their FAA written exams and parrot the definition of angle of attack during the oral portions of their checkrides. The relative wind seems to be the concept that’s hardest to get, especially in unusual situations and atypical flight attitudes. The name itself is probably the source of a good deal of the confusion: We think of wind as the movement of the air, but the relative wind is chiefly the product of the airplane’s movement through that air, regardless of what the air might be doing over the ground. Einstein would have had no problem with this, but the rest of us are apt to struggle.

Langewiesche makes this clear, thanks in no small part to Jo Kotula’s amusing but admirably instructive illustrations. (Readers of a certain age might note some similarities to Peter Aschwanden’s celebrated line drawings for John Muir’s timeless manual on How to Keep Your Volkswagen Alive.) Separate details show the flow of air over the wing and the “flippers” and how the latter determines the former. One commercial pilot of our acquaintance admits that he got through all his checkrides without ever figuring out what the relative wind really was or how to guess where it was going. One reading of Stick and Rudder made that clear.

After Langewiesche, one of the best explanations of relative wind, angle of attack, lift, and stalls comes in the Air Safety Institute’s own online course called Essential Aerodynamics: Stalls, Spins, and Safety. Since it’s available free to anyone who wants it, there’s absolutely no reason your instructors shouldn’t suggest that their students have a look, and some very good reasons they should. And if any of your CFIs haven’t read Stick and Rudder, you might want to ask them why not. Maybe they understand these crucial concepts so perfectly that no further improvement would be realistic, and that knowledge enables them to inoculate their students permanently against the risk of an unintended stall before they’re ever signed off to solo. Chances are, though, that further improvement isn’t completely out of the question—in which case student and instructor alike would benefit from a discussion so beautifully clear that it’s remained in print since World War II, helping hundreds of thousands of pilots figure out what they’re really doing up there in the air.

ASI Staff

David Jack Kenny

Manager, Safety Analysis
David Jack Kenny analyzes GA accident data to target ASI’s safety education programs while also supporting AOPA’s ongoing initiatives and assisting other departments in responding to breaking developments. David maintains ASI’s accident database and regularly writes articles for ePilot, Flight School Business, Flight Training, CFI-to-CFI, and other publications.

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