Features  / 01.13 /

The never-ending scan

How looking outside and inside helps you to be a precise pilot


scan

Flying is often compared to boating. They say we are “sailors in that great ocean of air above us.” But that’s wrong because, with the exception of submariners, sailors only have to deal with port and starboard, while pilots have to worry about up and down, as well. When the demanding third dimension is tossed into the equation, we actually bear more relationship to jugglers than sailors in that we have to continually shift our visual and mental focus from one thing to another.

If you watch a juggler’s eyes, you’ll notice that they are always in motion, always tracking what’s coming up as well as what just went past. And they do so in a very predictable pattern because juggling is a motion that continually repeats itself. In flying, just as it is with juggling, there are certain factors that we know we must control. And, depending on what portion of flight we are in, we know the way we visually cycle through flight information is always the same, although the cycle time changes. Sometimes we have lots of time to absorb information and make corrections. Other times, as in landing, the balls seem to flash past at a blinding speed. Still, we have to stay on top of them.

Although there is no single way to absorb all the sources of data our airplane offers, many CFIs have reduced it to some sort of handy acronym, such as RAAT (Rpm, Altitude, Attitude, Track). This is an oversimplification of the information that must be scanned. It could also falsely lead to the assumption that you fly by the instruments, not a combination of visual information from outside the airplane and the instrument panel.

When setting up the scan, the primary source of information is first the windshield and the feelings generated in your body, followed closely by the instrument panel. The panel is our verifier. It reduces what you’re seeing and feeling to decipherable numbers, making them easy to judge. The scan goes across the windshield (and windows), then across the panel and repeats itself every few seconds. The eyes never fixate on any one thing. The instant the eyes stop moving and spend too much time looking at a single piece of information, it can be guaranteed that something else is being ignored.

RPM. This is one of those basics that’s hard to misconstrue—especially in light aircraft with fixed-pitch props, where rpm
actually is the power being generated. In an airplane with a constant-speed prop, rpm is replaced by “power” and you’re monitoring the manifold pressure, not the rpm.

Rpm/power is a single number with no interpretation involved. What can we do other than verify it’s at the right number? For one thing, we can match the rpm, or power level, to the flight regime we’re in and make sure it’s right for what it is we’re trying to accomplish. On climb, the engine should be producing a certain number. Is it? On approach, if you’re flying a power-on approach, you want to verify the reduced setting you’re using matches what’s appropriate for the situation. All parts of the pattern—downwind, base, and final—may call for different initial power settings, which then are adjusted to put the airplane on the runway at a predetermined point.

Altitude. This also is a pure number with little or no interpretation involved. The only real question is how precise are you trying to be? On turns around a point, for instance, are you going to be satisfied with the FAA minimum requirements as outlined in the practical test standards (plus or minus 100 feet)? Or are you going to tighten them to personal standards of plus or minus 50 feet? Or 25 feet? Or even zero tolerance? Regardless of the margins mentally set and regardless of the airplane’s stability, holding a precise altitude requires checking and rechecking to catch it the instant it starts to go outside of the margins we’ve established.

Attitude. “Attitude” is another way of asking, “Is what we’re seeing out of the windshield going to give us what we’re looking for in terms of speed and direction?” An awful lot of what we see on the panel happens first in the windshield. The nose attitude controls our speed, so when it changes, so does our speed, and to a lesser extent our altitude. There is absolutely no way we’re going to hold either a stable speed or altitude if we aren’t holding a stable nose attitude that is appropriate for where we are in our flight. The sight picture in the windshield will be different on a cross-country, in the pattern, or flying the approach. So an important part of our scan is making sure that picture is exactly what we want it to be—and that it stays that way. Let the nose move around, and everything else will also be moving. In an approach, a stable nose attitude is everything.

In the beginning, a student’s visual acuity is understandably going to be weak. He’s never looked over an airplane’s nose before, so he’s not exactly sure what he’s looking for. Students often find themselves leaving nose smudges on the artificial horizon’s glass: It’s an easy-to-understand instrument, so they get fixated on it. This is OK as long as they realize that the function of most of the instruments on the panel is to help us understand what we’re seeing in the windshield, and calibrate our visual acuity so we aren’t as dependent on the instruments.

The goal is to give us a visual understanding of exactly what the changes in nose attitude are telling us and how, if we control the nose, the instruments are naturally going to follow. Not the other way around. The windshield is the primary. The instrument panel is secondary, and it is there to confirm what we’re seeing. However, because we’re constantly scanning both, neither is an exclusive source of information. We blend them together to understand what the airplane is doing.

Another instrument that often is ignored in the attitude part of the scan is the skid ball. While the eyes will eventually be able to tell when the nose is yawing at the wrong time, body sensations, specifically sideways pressure, are an immediate source of that information that even an aviation novice can feel. However, including the skid ball in the scan tells him what his body is feeling and, there too, calibrates it and gives dimension to his sensations. Once he has that imbedded in his instincts, he’ll already know that the ball is off center before he ever skims across the panel as part of his scan.

If a pilot is aware of what is happening in the windshield and is aware of what the sensations in his body are telling him, he’ll never accidentally spin an airplane. Combine that with a constantly moving scan, and you have a terrifically safe, precise pilot.

Track. The track aspect of the scan refers to the path across the ground. The track across the ground is the primary ingredient in what we’re actually trying to do with an airplane. We’re almost always going from A to B, whether the two points are 200 miles apart or at opposite ends of downwind. We always have interim destinations (checkpoints) in mind, and we track our progress in our windshield scan.

A good way to visualize the track is to imagine that the airplane casts a black shadow on the ground directly under it. We’re trying to control where that shadow goes at all times and, because of wind correction, our nose may not be lined up with the desired track. This is why we have to check it every few seconds as our scan goes through the windshield. This continual checking of our ground track is critical on cross-countries but becomes even more so while in the pattern because the dimensions and time frames are so short that a minor hiccup in controlling our track means we arrive at the runway a in less-than-precise manner.

On making corrections. All of the factors being monitored are more easily controlled if you are determined that the instant something isn’t right you’re going to correct it. If we put off making needed corrections, they will pile up until we have to make a number of them at the same time. Maybe while our altitude was drifting off, we also weren’t paying attention to our track across the ground, so we’re not only at the wrong altitude, but we’re not where we want to be in relation to our course. If we’re on a cross-country, that’s a less critical, more easily corrected factor. If we’re in the pattern, where everything is crowded together, letting a number of factors get out of limits means multiple corrections—and things get very complicated very quickly. By correcting each factor as it starts to go out of whack, we’re not only dealing with one at a time, but each correction will be smaller and more easily managed.

It’s difficult to overestimate the importance of keeping the eyes moving: windshield-panel, windshield-panel. The cycle is constantly happening and, even when sightseeing and examining something really interesting below, our eyes are still flicking through the cycle: rpm, altitude, attitude, track. A side benefit of this kind of scanning is that you’ll soon understand intuitively what the windshield is telling you. Then, if you were to lose every instrument, you’ll still be in full command of the airplane.

Budd Davisson is an aviation writer/photographer and magazine editor. A CFI since 1967, he teaches about 30 hours a month in his Pitts S-2A Special. Visit his website.


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