The elements of a good approach should include:
- We're on the centerline.
- Have a stable glide path aimed at a specific point on the runway.
- Airspeed over the threshold is stable and dead on.
- We have the airplane set up in the right configuration (flaps, trim, etc.).
A good touchdown might be defined as:
- It occurs at minimum practical speed.
- The touchdown is on the mains (for a tricycle-gear aircraft).
- The nosewheel is held clear as long as practical for the situation.
- The airplane is perfectly straight and ground track is on, or parallels, the centerline.
- The airplane stays straight after touchdown.
When flying an approach, about a million factors come into play, but the one that controls the entire package could be labeled precision. Everything we're trying to do in the approach has a specific parameter (speed, altitude, ground track) attached to it, and throughout the entire approach we're going to do our level best to make sure each of these factors is as exact as we can make it.
The first rule of order when flying the approach is to decide exactly what line we're going to fly and where it's going to terminate. The approach itself can be visualized as a three-dimensional line that is the intersection of two flat planes. One plane comes vertically off the ground and represents the airplane's ground track. In a normal approach, that should be the runway centerline. A second plane that lies horizontally represents the glideslope, and the intersection of the two makes up the final approach path.
We select a specific point on the runway as an aiming point for the line (the glideslope). Rather than just saying that we're aiming at the first part of the runway, we're going to aim for a specific point, such as the runway numbers or the threshold. If we use the numbers as our glideslope reference, that almost guarantees two things: First, we won't land on those numbers using normal speed control because, when we flare, we'll float beyond that point. Second, because we referenced the numbers, we'll come over them at a reasonable height (20 feet sounds reasonable, doesn't it?) and touch down 400 to 600 feet past them--which for most landings is short enough--and we'll be able to turn off at approximately 1,500 feet with minimal braking.
| Inconsistent airspeed control is one of the main causes for inconsistent touchdowns. Five knots, although within practical test standards, can make a big difference. |
| To control attitude changes in the flare, focus on both sides of the runway a few hundred feet ahead, and continually judge that relationship to the airplane's nose. |
| The landing game becomes more challenging when crosswinds are a factor. Keep the nose straight with your feet and neutralize any drift with the ailerons. |
Lack of airspeed control is probably the single largest factor behind inconsistent touchdowns. Although the Practical Test Standards give the private pilot applicant latitude in airspeed control (minus five knots, plus 10), the only thing that kind of inexactitude guarantees is that the pilot will never experience the same landing flare twice. A difference of as few as five knots right at the point the airplane is flared totally changes what happens from that point on. If five knots below the optimal speed, the airplane will bleed off speed quickly and settle through ground effect with a minimum of float. Be five knots over the POH-recommended speed, however, and the amount of float increases many times over.
Too much speed causes the airplane to hang there in ground effect longer, which gives the wind more time to mess with it. Higher speeds make the elevator more effective so inadvertent ballooning is more likely. The wind becomes a factor in the way it interacts with speed in the flare. A steady wind is of no consequence, as nothing actually changes, but a gusty wind can have a huge effect in terms of the aircraft either ballooning or falling out of the sky. Since gusts can change the airplane's airspeed for just an instant (until it has time to react to it), there is the possibility of ballooning up on a gust and then falling out of the same gust when it suddenly dies.
Carrying too much speed into the flare aggravates the tendency to balloon, so a gust only makes it worse. However, if a little fast, the abrupt nature of falling out of a gust is softened because the airplane has more speed left. If you're slower and a gust picks you up, the airplane was already in the act of decelerating, so it has slowed even more by the time the gust dies and it falls off the edge. That's one reason why, in a gusty condition, the rule of thumb is to carry half the gust spread over approach speed as a protective margin. The tradeoff is that the airplane is more pitch sensitive in the first part of the flare.
The process of controlling the touchdown actually begins the instant the airplane hits ground effect and we start setting it up for landing. When we gradually pull it into level flight right on the top of ground effect, the airplane has zeroed out its rate of descent. If left alone and the nose attitude is left unaltered, it'll slow down gradually and, as the lift decreases, fall towards the ground in a slightly nose-down position. The decreasing speed/lift affects the tail as well as the wings, so the tail becomes less effective and it comes up slightly.
The trick is to understand, and control, the tradeoffs that are continually in process while flaring an airplane. It's a combination of rate of attitude change (how quickly you up pull the nose), versus the height above the ground, the rate at which the airplane is descending, and the remaining airspeed. We want to bleed off the speed by changing the nose attitude at a rate that puts the airplane in the right attitude for touchdown, keeps it barely off the ground, and zeroes out the rate of descent. When we start the nose up to flare, it stands to reason that, if we pull just a little too hard, the airplane stops coming down, changes direction, and--for the briefest of moments--moves up and away from the runway. Not to worry: Gravity always sorts that kind of thing out. Unfortunately, while moving away from the runway, we're burning speed fast and, when gravity does its thing, we fall out of the air.
To keep our attitude changes under control, we need to focus, actually fixate, on both sides of the runway a few hundred feet ahead of us and continually judge their relationship to the nose. Don't just stare at the centerline, because it won't give you enough information soon enough. If you click back and forth from one side of the runway to the other several hundred feet ahead, your binocular vision gets into the act and your ability to judge height is much better. Plus you'll pick up any wind-induced drift much sooner.
The aim of fixating on the edges of the runway is to pick up on the tiniest changes in our rate of descent and control them. You can't control what you can't see, so the first goal should be to develop our visual acuity to the point that we see changes in height and direction much more quickly than we do now. The better we can do that, the better we'll be at controlling the airplane's movement toward the ground.
As the airplane starts to settle, we want to control its rate of descent while slowly rotating the airplane's nose into the touchdown attitude. This is not one big, slow pull on the yoke. In fact, it's something of a saw-toothed input pattern: you stare at the edges and see the airplane is slowly moving down, so you put in just enough elevator pressure to stop the downward movement. A nanosecond later, it starts settling again, so you increase back pressure, which brings the nose up a tiny bit, while still holding the wheels off the ground.
The "hold it off" game continues with you slowly working your way toward the runway and the nose slowly coming up. The closer to the runway you get, the more critical your movements become, and the more obvious it becomes that this game is much easier if you're right on speed from the beginning. This is where flying a fast approach gives you the most heartburn. This is especially true when using full flaps on a Cessna and loaded lightly. If you're fast, expect a tug of war right at the end while you're trying to get rid of the extra speed and still keep the nosewheel clear of the runway. A gentle touch combined with really sharp vision helps here.
This game becomes a lot more fun if you're fighting a hard crosswind. Fortunately, the technique is essentially the same, but you're also paying strict attention to the alignment of the nose with the centerline and any drift that may have developed. Don't complicate your life by thinking "cross-control." Just keep the nose straight with your feet and neutralize any drift with the ailerons. If you do that, your feet will automatically cross-control if the amount of aileron required to overcome the drift is enough to cause the nose to move.
In any case, as soon as the airplane touches down, you'll probably need just a hint of increased back-pressure to keep the drag on the wheels from pulling the nosewheel down. Sometimes it's difficult to prevent this, but if we're going to create a work of art, we need to do what we can to keep the airplane balanced on its hind legs. Then, after the airplane has rolled a few hundred feet, gently lower the nose to the ground; don't wait too long and let it fall of its own accord, when the tail runs out of air.
This sounds like a lot of work, but it's a fun game. The result is a landing that feels more professional and looks better. And, you'll be paying more attention and touching down slower and more smoothly, so it'll be a safer landing as well. What's better than looking good and being safe while doing it?
Budd Davisson is an aviation writer/photographer and magazine editor who has written approximately 2,200 articles and has flown more than 300 different types of aircraft. A CFI since 1967, he teaches about 30 hours a month in his Pitts S-2A Special. Visit his Web site.
