The Mystery/Controversy: The controversy, which has been around for at least 70 years, is this: How does one best control airspeed and glideslope on the approach? The instrument approach in question was originally an ILS, though today LPV approaches have a glideslope (technically a âglidepathâ) as well. In the seminal aviation how-to book âStick and Rudder,â written in 1944 by Wolfgang Langewiesche, the author says itâs the counter-intuitive way, pitch for airspeed and power for glideslope. And since then (if not before), this method has had its passionate adherents.
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The Controversy: Langewiesche has an almost cult-like following among pilots, and for good reason. âStick and Rudderâ reveals flying in ways that pilots have never thought of before. Many have called the author a genius. We wouldnât argue with that assertion. Still, Pitch for Airspeed and Power for Glideslope isnât the only way to pull off flying a good ILS or LPV. A pilot could do the exact opposite and still stick a perfect 10 all the way to minimums if they were on their game.
Alternative Method One: As we said, reverse it. Pitch for altitude and power for airspeed. Thatâs the intuitive way. We all grew up thinking that the throttle makes us go faster, and, all other things being equal, it does. And when we learn to fly, on our very first lesson, we are taught that if you want to go up, you pull back. To a point, those techniques work great.
The problem has been explained this way for ages: âPull back, and the houses down there will get smaller. Keep pulling back, and theyâll get larger again.â Itâs funny because itâs true. In a weightless world, the elevator would be the be all and end all, but we are not weightless, nor are our planes. Itâs the same with the concept of using throttle for airspeed. Unless youâre flying an F-16 (and maybe even then), throttle will only get you so far. Get behind the power curve (which is a real aerodynamic concept, by the way), and youâd better start pushing forward or look out for those big houses below.
Still, even if itâs not the only way to fly, you absolutely can maintain airspeed with power and altitude with pitch. Itâs just that there are limits to both techniques.
Alternate Method Two: Let âGeorgeâ do it. And how the autopilot does it is precisely the opposite of how Langewiesche suggested human pilots do it. If youâre low on glideslope, the autopilot will raise the nose, not with power but with pitch, of course. Few autopilots have the luxury of sharing the cockpit with an autothrottle system. But on planes with autothrottles, the approach is flown in âspeedâ mode, and the throttles maintain the selected speed. The autoflight system keeps the glideslope with pitch.
Alternative Method Three: Use both methods simultaneously. This, in actuality, is how most pilots fly. If youâre low on glideslope, you might be getting too fast, too. Raising the nose will get you back toward the desired flight path, but it might slow you down too much. So you increase power a smidge. Corrections are made using small inputs and doing it almost constantly as you aim to keep the approach on the rails.
The Truth: You can fly a good approach using either method or, as is most often the case, a combination of the two. Still, if the Pitch for Speed and Power for Altitude work for you, thereâs no reason not to use it. But other pilots might differ, and as long as their method translates into stabilized approaches and happy arrivals, thatâs okay, too.
