HOW TO FLY
MAKING (AND TEACHING) CROSSWIND LANDINGS
In reviewing all the skills and tasks that student pilots must master, four areas in particular stand out in terms of both difficulty and importance. In fact, they tower head and shoulders above the rest.
Broadly, they are:
In the main, the difficulty attached to all four stems from their "newness:" they are unique to aviation and require understanding and skills that are not intuitively obvious. Some, like crosswind management, are actually counter-intuitive.
For CFIs, the teaching skills brought to these tasks are the measure of excellence. For students, the thoroughness with which they are learned is the measure of success. Each plays a crucial part in the overall quality of the finished product, and each has its own specific challenges.
Thanks to the inherent stability of the tricycle design, the touch-and-go student can usually straighten out at this point and take off again, with little or nothing learned. Many never progress much beyond this level, and some find later to their chagrin there is a limit to the punishment the landing gear will endure. Tailwheel pilots, of course, are forced to learn a bit more quickly, but the continuing frequency of ground loops is evidence that there are still lots of unsolved problems in the area.
Pilots who never master effective crosswind technique are doomed to a lifetime of uncomfortable sideloaded landings. Some land crabbed, some drifting. The crabbers arrive with the nose pointing sideways, counting on being able to straighten out after touchdown. The drifters land with the fuselage properly aligned, but with the aircraft drifting inexorably toward the runway edge. These landings become a race to get on the ground before running out of pavement, and many pilots solve the problem by simply planting their planes on the ground early and fast. Crabbing and drifting sort of work in light winds, but both are hard on equipment and say little for overall ability. In stronger winds, you often see bent parts.
THE CFI CONTRIBUTION
Wind does, however, have a definite effect on the track of the plane across the ground: to the outside observer, a plane flying in a crosswind appears to be moving sideways--;which is why flight in crosswinds is called "crabbing." The sideways motion is, as stated, an aerodynamic illusion--;the plane is moving perfectly straight through the airmass--;but the drift across the surface of the planet is real enough. At the moment of touchdown, this sideways movement becomes a problem: failure to align the aircraft fuselage with your groundtrack results in sideways impact on the landing gear.
The keys to successful crosswind landings are good rudder use and a thorough understanding of what happens when the wings are banked. Most instruction on the subject is delivered this way: "control heading with rudder and drift with aileron." The instruction is twice flawed: it fails to establish a proper sequence and mistakenly saddles the ailerons with drift control. The ailerons are merely a tool for moving the plane around its longitudinal axis--;the resultant bank angle is what actually controls the wind. Better would be: "point the airplane where you want with your feet, then bank the wings to control drift."
While accurate, this description is too simplified for most students: the learning task is complex, made so in part by the fact that both aileron and rudder can apparently each be used to do the other's job. Additionally, a lifetime of aiming cars with a steering wheel is not likely to be abandoned instantly because of a single sentence of instruction.
There is a further complication: crabbing is instinctive--;it's fair to say everyone emerges from the womb knowing how to do it--;but crosswind slips feel unnatural and require disciplined effort for mastery. What finally works for most students is the adoption of a hard and fast set of actions. Unfortunately, the sequence is not immediately obvious to every CFI and student:
If all this seems a bit mechanical to you, let me say first that it works, and second that what it is intended to do is simply arrange the proper order of priorities: alignment first, then drift. You should find it helpful.
THE LEARNING PROCESS
The main point is to make sure at all times you keep the aircraft fuselage aligned either on or parallel to the centerline. This is no more complicated than taxiing, and is in fact the same action, done entirely with rudder. Naturally, the minute you do this the airplane will begin drifting off centerline, and it is at this point you must exercise the first disciplined effort. DON'T succumb to the temptation to return to the crab--;instead, use aileron to lower the upwind wing until you see the drift stop.
So far so good, but now the airplane will want to turn. Here comes the second disciplined effort: DON'T lift the wing back up--;instead, use opposite rudder to keep the airplane straight.
Immediately, you will notice two things: slips are mildly uncomfortable and they increase drag. If your approach was perfectly set up prior to establishing the slip, it will be necessary to add power to compensate for the added resistance.
A third observation will develop over time--;the wind doesn't stay constant, making a steady stream of small corrections necessary as you continue to prepare for touchdown. If the crosswind component drops a bit; the airplane will start "drifting" UPWIND. Stop this movement by taking out some of the bank. Then continue the chore of keeping straight with rudder. If the crosswind component increases, you will start drifting downwind; it may take a little discipline to resist the temptation to rudder the nose into the drift. Instead, as in step 3 above, bank a little more and add an appropriate amount of increased opposite rudder. Flexibility is the key: there is no way you can remain with controls frozen in one position. Simply keep repeating steps 3 and 4., and if the airplane gets crooked at any time, go back to step 1.
The final "hard spot" starts to crop up as you bleed off speed over the runway just prior to touchdown. Perhaps predictably, students are generally unwilling to land in a banked attitude, so right before touchdown it is common to see beginners level the wings in an attempt to touch both mains at the same time. It's a shame, as the action undoes all the good work that came before: the minute the wings are leveled, the plane starts to drift sideways, and touchdown is made with sideload. It is important to realize that a successful crosswind landing requires a banked arrival and initial touch on one wheel.
Touchdown observations also reveal an inherent weakness in the "other" method sometimes taught for handling crosswinds. Called "crab and kick" (and other endearing names), the technique recommends crabbing all the way to the point of touchdown, then kicking the nose straight just before both mains touch the ground, wings level. The technique is touted as easier than learning to slip, but has a major flaw: it is a rare pilot who can consistently predict the precise moment of wheel touch. In fact, unless you make no-flare carrier type approaches and landings, it is virtually impossible to predict exactly when you will touch. Any error--;kicking too soon or too late--;results in sideload. And remember, landings made with inadequate or no crosswind correction are called "bad." Why learn that?
Even large airplanes, like airliners, are landed in slips--;the trick being that their pilots, for reasons of passenger comfort, learn to wait until virtually the last possible moment before replacing the crab (comfortable) with the slip (uncomfortable).
The intuitive answer may appear to be that the bank angle needs to increase to compensate in some way for the diminishing speed. In fact, the angle remains the same. You don't lose lift during the deceleration, so the counter effort provided by a given angle of bank remains constant--;just the right amount to handle the crosswind.
But something else does change: the control inputs--;rudder and aileron--;needed to preserve the slip. As you slow, the control surfaces lose authority, and more and more deflection becomes necessary. This is, in fact, the source of the ultimate limiting factor in managing crosswinds: all aircraft eventually run out of one or the other control surface--;it is usually rudder--;as they slow down and try to maintain a slip. In aircraft with very limited slow speed control authority, crosswind management dictates high touchdown speeds--;anything slower risks loss of directional authority.
In addition to creating crosswind difficulties for some models of aircraft, the increased control deflection necessary at slow speeds creates an ironic problem for students: just as the last of the "hard spots" begins to emerge--;the student's unwillingness to touch down in a banked attitude--;the control deflections necessary to remain banked demand more attention and effort. The result? In the hands of the unwary, the plane seems almost to level the wings on its own, and then lands sideways. The solution, of course, is to remain conscious and in control of aircraft position and behavior throughout the entire flare and touchdown. That's why you practice.
Using low passes only--no touchdown--;fly down the runway with the student on the rudder pedals and CFI on throttle, elevator and aileron. Tell students they have control of heading only and should work exclusively on keeping the fuselage parallel to the centerline--;not on it, just parallel. The CFI does the rest. NOTE: this techniques only works when the student knows where the plane is actually pointed--;some ground instruction may be necessary.
After several successful passes, trade places. The CFI gets the rudder and retains throttle--;students get aileron and elevator. Now tell them that their job is to maintain altitude and attempt to keep the plane over the center of the runway by changing bank angle--;you'll do the rest.
After several repetitions, the lights should go on, and although it will be necessary to continue practice, you should now see satisfactory progress with every repetition. If you don't, go back and work on the simplified drills some more.
Four more tips:
One: Low passes are by far the best way to teach all landing skills. Simply have students attempt to maintain altitude down the runway at ever decreasing heights--;five feet, three feet, and finally one foot--;until a go-around becomes necessary. By tripling elapsed time over the runway, the passes significantly accelerate the entire learning process for both altitude and drift control. Free of concerns about touchdown, students can concentrate on the visual and mechanical skills necessary to maintain slow speed control. When CFIs feel things have progressed sufficiently, they simply reduce power to the point that touchdown becomes inevitable, and students "land" without ever trying to. Perfect result.
Two: During low pass instruction, teach altitude control first, then drift. In other words, let students crab down the runway until they master the visual cues, inputs and anticipation necessary to maintain altitude +/- 6 or 7 inches. Then add crosswind drills.
Three: The centerline is a reference, not a target. If students drift off center and then get the wind solved, it is usually satisfactory to let them touch down where they are, without slavishly insisting they return to dead center. Of course, there are limits, but in general, if the student's ability is so limited that the edge of the runway becomes an issue, the right response is a go-around, followed by more low passes.
Four: In light winds, it is often difficult to teach crosswind landing control because the effects are subtle, and it is easy to get away with ignoring them. Here's a good tip: cut the runway in two, lengthwise, and limit students' low passes and eventual touchdowns to the upwind half. The technique will make even a mild crosswind visible.