The driving fallacy

March 1, 2004

Bruce Landsberg, ASF executive director, has taught dozens to fly and confused thousands.

"If you can drive a car, you can fly an airplane." It was a great marketing idea concocted during one of general aviation's golden ages. The message was that flying could be every man's or woman's sport. Cessna is credited as being the source, and the phrase is frequently repeated as evangelical pilots promote the joy and ease of flight. Personally, given the shenanigans of many of our fellow motorists, I remain unconvinced that we would want anything to do with them in the skies. And yet, we'd like to grow general aviation into a stronger, larger community. The question is whether prospective pilots should be led into thinking that FAA certification is a walk in the park.

One aircraft company chief executive officer who believes in his product, as any good marketer does, said, "We thought of building a plane that was as easy to drive as a very good car." Another claims an aircraft will "free your mind." Perhaps it will. Advertising hyperbole has always been with us, but when it comes to a pilot actually telling someone that cars and planes require equal levels of skill, I have yet to fall off the turnip truck. I'll also quietly admit to having been guilty of the offense in the past, but I've reformed.

Back in the really old days, 1944 to be exact, Wolfgang Langewiesche wrote in the opening sentence of his classic book, Stick and Rudder, "Get rid at the outset of the idea that the airplane is only an air-going sort of automobile. It isn't. It may sound like one and smell like one, and it may have been interior-decorated to look like one: but the difference is — it goes on wings." For 384 pages Langewiesche expounds on how wings are different and illogical compared to earthbound objects.

We might examine how cars and airplanes are different, which should lead to a better understanding for prospective pilots of what flying is all about. In a car, when one control input is made, usually only one thing happens. Take your foot off the gas and the car slows. Step on it and there is acceleration. Turn the wheel in either direction and the vehicle goes that way.

Not so with airplanes. Reduce power and the beast doesn't slow down. Without pilot intervention, it will maintain trim airspeed and descend. That isn't how an automobile would behave, at least the one I drive. Add power and the aircraft will begin to climb; it doesn't accelerate. Turn the yoke or stick and the flight path will curve, but darn if the airplane won't also want to lose altitude. I've explained all this to new students before we go out for an intro flight lesson only to get bewildered looks once airborne. I probably told them too much! The logical (to us) and perverse (to them) nature of today's airplanes is still very much a force to be reckoned with. The most remarkable non sequitur — which has nothing to do with cars — is what happens if one keeps pulling back on the yoke.

NASA visionaries and others have mused about really making flying as simple as driving, and I'm convinced that it may be technically possible but it isn't likely to happen in the next few years. With a program called SATS, or Small Aircraft Transportation System, NASA engineers believe they can fix all the quirks of aircraft control, but it will probably take a fly-by-wire approach. Like the latest-technology fighters that are too unstable for the human pilot to handle, an automobilelike aircraft will need to really simplify control response: one input, one output. The technology will need to be really smart, really complex, and really reliable. There's also the slight matter of affordability. I have great faith in technology but am a bit more skeptical about economics. Of course somebody who doesn't know that this can't be done will be successful, but until that happens I'd suggest not using too many driving metaphors because they don't quite fit. Let's make some comparisons.

Neophytes are often told that the airspeed indicator is equivalent to the speedometer. Well, not exactly — a speedometer measures speed over the ground, not through the air. It takes most students at least an hour to understand the difference between airspeed and groundspeed, never mind the other varieties of speed: true, calibrated, equivalent, and so on. Some never quite get it. I've never seen a car speedometer with red arcs and yellow, green, and white zones. My dad had a V NE speed that he laid down for me as a new teen driver in the family flivver, which I promptly ignored, and fortunately no solid objects got in the way. The car did fine. Ignore V NE in the air and watch what happens.

You can get altimeters and compasses in cars but they tend not to be very satisfactory. Airspeed, altitude, and heading are what make safe flight possible. In cars, slow speed is the safest except in the left lane of a superhighway, where you will be flattened or flayed by other drivers. In aircraft, slow speed makes flight impractical or impossible. If an automotive altimeter is appreciably different from the local road elevation, very bad things may be about to happen. In airplanes, altitude in relation to the ground is your friend. In cars, compasses tend to be novelties and, if you're lost, only succeed in further confusing you. In today's world of GPS much the same could be said about airborne compasses, but we can always hope that some shred of dead-reckoning skills will survive.

You've probably also never had to switch fuel tanks on a car unless you drove an old Volkswagen Beetle, but it's something we do on every flight in many aircraft. Nor have you ever had fuel siphon out of an auto tank if the cap was loose. Nor have you thought about fuel in hours and minutes, but in miles per gallon. And if the trip to Grandma's took four gallons by car, it pretty much always took four gallons. In the air, that groundspeed concept can make a significant difference in whether I get to Granny's on one tank of gas, have to refuel, or wind up landing off airport some place. You've never had to adjust the engine mixture while cruising down the highway, no matter what the altitude. Some pilots don't do this in an airplane, either, and don't make it to Granny's because of fuel flow problems.

What about stalls? There just isn't an automotive equivalent, and that's one of the reasons why Langewiesche wrote Stick and Rudder. The news media constantly confuses automotive engine stalls with aerodynamic ones. That third dimension, fluid dynamics, and applied physics really do change the flight environment. As we all know, this doesn't mean you have to be a math major to fly, but some good instruction on basic concepts of aerodynamics is required. Unfortunately, our safety record reflects that too many pilots apply automotive thinking when airborne.

There are some car-airplane similarities, however. Analog engine instruments are pretty close, except that modern autos have far better annunciator packages than the classic aircraft fleet.

CD players are now commonplace in both vehicles, although I prefer that the pilot in command be listening to the aviation business side of the audio and leave the reggae, rap, rock, or talk to the passengers. Noise-attenuating headsets are not normal requirements in most cars either, although as a poor college student, I drove an old Plymouth with a rusted-out muffler for several weeks when an intercom and headset would have been useful.

Any CFI can attest to the "negative transfer" of auto knowledge to airplanes. It starts early, just after asking the would-be pilot to taxi. They grapple with the yoke and become totally bewildered while the instructor smugly points out that on the ground, we steer with our feet.

Once in the air, turns take on even more complexity. In addition to the nose dropping during turns, some rudder is needed to overcome adverse yaw — there's not much in modern aircraft but it's considered good form to correct for it. So for a normal turn in the air we'll turn the yoke, add some back pressure, and apply rudder. In cars, just turn the wheel and don't overthink it. But wait, there's more. In a car, to keep turning, the wheel must be held in the turn. In airplanes, hold the wheel only until the desired bank angle is reached and then neutralize it, or keep holding it until the aircraft becomes inverted and the new pilot decides that maybe flying isn't quite what he or she thought it was going to be. If you happen to get inverted (not recommended on the intro flight), we probably should mention that down is "up" on the pitch control. Just some more aeronautical logic to absorb.

Of course most airplanes have differential braking and the pedals have two functions, well, three, actually. The top part of the pedal (usually) stops one wheel, while the bottom part of the pedal (usually) moves the steerable nosewheel on the ground and also moves the rudder when airborne — but the rudder is not how the aircraft turns when airborne. That's done with the wheel or yoke, which you remember, doesn't work for steering on the ground. Whew!

"Now let me see if I've got this right," says the budding aviator, eyes now glazed with details and trying very hard to see how automobiles and aircraft equate. It can be a little disillusioning because we've created an expectation that won't be so easily fulfilled. Maybe a better way to approach the third dimension is to leave ground vehicles on the ground. We want to develop airmanship and that's hard to do when thinking in two dimensions at one-third the speed. Learning to be a pilot is a bit tougher than learning to drive, in ways far beyond the economic differential. You know the value, the satisfaction, the pleasure, and the camaraderie, as well as the effort that go with being a pilot. It's not for everyone, and driving a car has precious little to do with selling aviation. We can stand on our own.