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HOW TO FLY
MICHAEL CHURCH
JUNE 1999

LEARNING TO LAND


Solo! Every student's dream, every pilot's fondest memory. To get there, you have to master a long list of skills and a whole library of knowledge; more than anything else, it seems, you have to learn to land.

Undeniably complex, the process of learning to land is often made harder than necessary by failure to separate the wheat from the chaff--that is, failure to understand which pieces are most important, which are least. You may be surprised at some of the conclusions that follow...

GREAT LANDING!
Years ago, flying as a passenger in the Caribbean, it was fun to participate in the ritual applause that always followed a successful landing. The passengers weren’t particularly discriminating: any landing that left them unharmed qualified.

Consulting a slightly more informed point of view, it is interesting to look at the criteria that pilots themselves use in evaluating successful landings. Tongue-in-cheek references to "...if you can walk away from it..." are amusing, but most pilots are much harder on themselves when it comes to serious discussion. The grading resolves to four major areas: SLOW, CENTERED, SOFT, and CROSSWIND SOLVED. A good place to start the discussion is to attempt to list the four in their order of importance. Which is most important, which least?

In contrast to most commercial passengers, pilots of light aircraft should put "SOFT" at the very end of the list. It simply isn’t the be-all, end-all that it might at first appear. Almost equal in its lack of importance is CENTERED.

Most important? It’s a toss-up between "SLOW" and "CROSSWIND SOLVED."

First, the arguments for SLOW:
"Son, airplanes are built to fly, not roll," someone once told me (it was a long time ago).

He had a point. Would you drive a 4-place Cessna on the highway at 60 mph? The compromises and trade-offs inherent in landing gear design make it a poor bet: small wheels, light-weight components, minimal brakes and marginal steering are at the top of the list of disadvantages. Couple these with the awkward handling produced by a high center of gravity and a thirty foot wingspan and problems multiply.

These factors, which have not changed significantly since the earliest years of aircraft manufacture, form the basis of one of the most important rules in aviation: GO AS FAST AS YOU LIKE IN THE AIR, BUT AS SLOW AS YOU CAN ON THE GROUND.

More than just dictating slow taxi speed, this rule naturally affects landing decisions as well. Most light aircraft present a range of potential touchdown speeds to the pilot anywhere between 50 and 80 knots; the rule suggests you should aim for the lower end. Your goal should be to hold your airplane off the ground until reaching the slowest practical speed before you let it touch.

Thus, it is not just fancy technique that leads the best pilots to land only after reaching high angles of attack and slow airspeeds--it is good piloting. And it not just the desire for very short landing rolls that leads these same pilots to use full flaps on every landing. Again, it is good piloting.

I am not trying to suggest that landings made at higher speeds and lower angles of attack are particularly unsafe. Obviously, a pilot who lands flat and fast and yet survives would scoff at such a suggestion. What I am saying is that slow is better. In the normal way of things, slow landings reduce wear and tear on the airframe. From a risk management point of view, the reward is more dramatic: compare the results of a blown tire on touchdown at 70 knots to those produced by the same event at 50. It’s probably clear which airplane you’d rather be in.

There is an additional, more intangible, reward as well. The efforts involved in the attempt to keep your airplane from landing until you are as slow as possible cannot help but improve your overall skill. It is an often repeated refrain in aviation that continued challenge is necessary to ensure increasing ability.

Before completely leaving the area of slow landings, there are also the decisions about wing flaps to consider. First, it is necessary to agree why flaps are there at all.

Flaps are added to the wing to assist landings, and to some degree, takeoffs. In both cases, their major contribution is a re-shaping of the wing to make slower flight (and slower contact with the ground) possible. It is not the primary purpose of wing flaps to increase drag: that is just an added side-effect, one that could be much better accomplished through the installation of speed brakes and spoilers rather than flaps.

Full flaps on approach and landing serve the purpose of lowering minimum flight speed. This in turn allows slower approach and touchdown speeds that still maintain a comfortable margin from stall. Failure to use flaps inevitably dictates faster approaches, faster touchdowns and longer roll-outs.

All of these arguments for touching down at the lowest practical airspeed should have been convincing, but, like every good thing, even SLOW can be taken too far. I’d like to take up a poorly conceived phrase that is still quite popular in some circles for describing the ideal landing: "full stall." It generally comes up like this: somewhere in the middle of discussing the virtues of landing slowly, a pilot will nod sagely and say,
"Oh, yeah--you mean full stall landings."

Well, actually, no. Intentional stalls during landing may have had a practical application with some airplanes in the distant past, but I cannot think of one general aviation model designed in the last sixty years where an actual stall on landing should be a target.

To understand this, it helps to realize that stalls, by definition, involve a substantial loss of aircraft control. Aileron effectiveness, at the least, is greatly diminished, and the rapid change of airflow across the tail robs the elevator of almost all authority. The result is an airplane that pitches forward on its own with almost no aileron response.

What all this means is that although "slow" is good, the extreme of an actual stall is hardly something you want to experience when you’re close to the hard ground.

The term "full stall landings" is most often applied (incorrectly) to tailwheel airplanes, which appear to be quite close to stalling when landed tail low in the "three-point" attitude. Most of these aircraft are not really that close to stall, but there are exceptions: good examples are the Twin Beech and the DC-3. Although both can be three-pointed successfully without stalling, they are close enough to critical angle of attack that most of their pilots choose instead to make "wheel landings," using flatter attitudes and lower angles of attack.
With smaller tailwheel models, from Cubs through Cessna 180’s, the angle of attack on landing is not that extreme, and three-points are easily accomplished without risking stall. More than just a history lesson, these observations might serve to illustrate how easy it is for mis-conceptions about the basics of flying to perpetuate.

On to the next landing criterion: CROSSWIND SOLVED.
If you want your landing gear, your tires, and indeed your entire airplane, to last out their designed lifespan, this goal is just as important as SLOW. Uncorrected crosswind landings put unnecessary--sometimes dangerous--strain on the landing gear (and reveal, for all the world to see, lack of essential piloting skills).
The first element required in crosswinds is that you recognize their existence. Many pilots, especially when learning, make a misleading differentiation between "normal" landings and "crosswind" landings. Actually, there are very few "normal"-- zero crosswind-- situations. Consider: absolutely no crosswind means either no wind at all, or wind perfectly aligned with the runway all the way through the entire landing process. Neither is common.

Accept that premise, and almost every landing becomes a crosswind landing, presenting you with only two alternatives: solve the crosswind, or land sideways.

Solving a crosswind usually means mastering the technique of using the ailerons to "lean" the airplane into the wind and rudder to control heading. The resulting slip directs some of your lift against the wind and allows you to keep the fuselage (and landing gear) aligned with the runway without drifting sideways. It is definitely not the easiest technique to learn, and for some pilots remains a mystery forever. The rewards of getting it right show up in reduced maintenance bills.

Just how hard is this technique? Apparently, harder than I thought. I once saw an article in an otherwise respectable flying publication (that descriptioon might just suggest the name) that recommended not using any crosswind technique at all. Just crab down to the runway and land sideways, was this writer’s suggestion. Justification? The gear is built strong enough to absorb the sideload, and the basically stable tricycle design will straighten out the airplane on touchdown and make up for your deficiencies.

Nonsense! I suggest we all go out and hunt down this guy’s car someday and use his bumper to help us parallel park. Justification? It’s probably built strong enough to take it. At the risk of starting a fight, I assume this genius is one of those pilots who has always remained mystified by proper crosswind technique. Certainly, I can assure you that there are no aircraft rental outfits who would rejoice seeing him or any of his disciples turning into their parking lots.

That completes the presentation of the two most important criteria for judging landing quality: SLOW and CROSSWIND SOLVED.

Now, onto the remaining two: CENTERED and SOFT. As suggested at the start of this piece, many pilots mistakenly believe these two have the highest importance and use them almost exclusively to judge the success of their landing efforts.

Lets consider CENTERED first.
On final, the painted line in the middle of the runway is a useful target to help get lined up. As you arrive over the runway, however, the target value begins to weaken. Landings are not a single event phenomenon, and unlike a bullet, the plane does not just get aimed once and released. Instead, because you can continually correct and alter your flight path during the landing process, the centerline is most useful if not used as a fixed bullseye.

To understand this point, you should realize that once you recognize that you are drifting off center, you will probably find your attention naturally going to the approaching runway edge: your first order of importance will be to get the drift stopped and the crosswind re-solved.

Once you accomplish those two things, the need to actually move back to the centerline before touching down is not crucial: you can pretty much ignore it for the remainder of the landing. Conclusion: the most important point with centerlines is not to land on the "target," but simply to use them to help judge and then stop sideways motion so that conditions do not worsen. A good straight landing made even tens of feet left or right of center hardly qualifies as a failure.

But wait! What about Standards? What about Goals? Is it good enough to be Second Best?

OK. It’s best to be able to land exactly where you want every time. Unfortunately, a goal that absolute is absolutely unattainable. Although you should attempt to land precisely in the middle of the runway, complete success will be, at best, only third in importance, well behind SLOW and CROSSWIND SOLVED.

That brings us to SOFT. First in the heart of most passengers, last in importance to the pilot.

If you do everything else fairly right: aim for a slow touchdown, get the crosswind solved, and remain somewhat close to the center of the runway, you’ll probably do a good job with SOFT. The problem is, in a nutshell: even the best don’t succeed every time; there are too many variables.

Here’s how it works. Once you have made the transition from the approach segment to the actual landing flare, your primary job will be to hold the airplane off the runway and remain straight (crosswind solved). One way to look at this is that you will be trying to maintain altitude with the power off--a game you are bound to lose over time. Your vision should be "aimed" straight ahead, but your attention should be strongly on the peripheral scene. At each edge of your vision, the sides of the landing area will be visible, and you will use that reference for controlling sink and drift. Your three jobs: keep things straight, don’t let the plane go down, don’t make it go up. You are, in essence, keeping the plane from landing, rather than consciously trying to put it on the ground.

Note: If this approach to the time spent over the runway while you await touchdown is new to you, it deserves a try. It has these advantages: your attention is on the most important issues (drift and sink), and you have an ideal setup for dissipating airspeed until an acceptably low touchdown speed has been achieved.

Now, back to the subject of SOFT. In calm conditions, a little practice with everything covered so far should reward you with consistently slow, straight, centered, and soft landings. When things don’t work out perfectly, the quality that will suffer first will be SOFT, and the causes are likely to be factors you can’t control: wind shear and thermal activity. In other words, disturbances in the air that you can’t see and can only react to once they have done their mischief.

It is this unpredictability of the air that makes SOFT last in importance. No matter how excellent your aircraft control, there will be times when the plane will "thump" onto the runway. As long as you were flared low, crosswind solved, and reasonably slow, the thump won’t be important.

As with CENTERED, I am not suggesting that you should not aim to develop the skills necessary for soft landings. I am just pointing out the relative importance of SOFT as a goal: it is fourth, behind SLOW, CROSSWIND SOLVED, and CENTERED.

A last point: from fifty feet away, almost all landings look acceptably soft; its just a matter of perception.
Now that you know what's important and what isn't, you're ready to learn to land--the subject of another piece, sometime in the future. To tease you a bit, and to demystify the subject as much as possible, here's all there is to it, in the words of one of my teachers--a pilot accustomed to flying a wide variety of piston powered aircraft, from agricultural planes through classic warbirds:

"All airplanes land about the same. What I do is approach at the right speed, flare as low as I can, keep it straight, and hold it off as long as I can. Never gone wrong yet."

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