Photo: Tim Romano @Flickr.
Success starts with the approach
Even though landings constitute a minute fraction of any flight, they're typically the measure of its success. Most often this is judged by the smoothness of the landing; however, it isn't really an indicator of the safeness of the landing. The fact is, landings are one of the more error prone phases of flight, and I presume they account for the majority of aviation mishaps, but they're really just the finishing touch on the overall flight. Success in executing a smooth and safe landing lies in the well-executed approach, something we discussed in great detail in the first article of this series.
This is particularly true for landings in the backcountry, as most backcountry type airstrips or landing zones tend to be shorter and in somewhat "interesting" areas that require a level of precision that just isn't as necessary on a standard GA runway. And while some backcountry airstrips are plenty long, they still may have some characteristic that makes them more demanding on the pilot's skillset, like steep, tight terrain blocking a go-around. Of all the sectors of general aviation, powered single-engine operations probably focus on spot landing technique the least, in contrast to glider training, and even heavier turbine aircraft training, where precision landing is a skill that is expected and enforced. Suffice to say, the average GA pilot tends to be deficient in this area, focused much more on smooth touchdowns than overall used runway.The backcountry landing is geared toward safely using as little runway as possible, in stark contrast to the average GA pilot's daily technique of using as much runway as is necessary to "grease" it on.Photo: Bernal Saborio @ Flickr
In the backcountry we don't fly that much differently than the pros do. We fly a stable approach at the slowest possible safe speed to a pre-determined spot, much like an airliner on an ILS. However, we don't have fancy instruments and electrical guidance. Instead we must rely on experience, comprehension of theory, attitude flying, and lots and lots of practice. Nowhere is this truer than on landing. There is no simple panacea for a well-executed landing, but if you understand the theory and task for each part then becomes much easier to execute over time.
If you read the first part of this series then you know that we advocate a steep, stable approach flown at much slower airspeeds than usually accepted in the GA world. A well-timed landing to complete the flight follows this steep stable approach.
Per my own convention, I break the landing down into three distinct parts: 1) The Flare, 2) Touchdown, and 3) Rollout. Breaking it down like this, and understanding what's involved for each part simplifies what is an otherwise quick and complex task. The main objective is to constrain vertical and horizontal energy to the shortest distance possible. We can express this with a few physics formulas (extremely oversimplified but good for illustrating the concept): Momentum is equal to your mass times velocity, or P = MV. We want to minimize momentum, and since weight can't be changed mid-landing, the aircraft is a constant mass (a good reason to keep it lightly loaded) so the best way to manage momentum is by decreasing velocity. Recall that velocity is equal to distance divided by time, or V = D/T. Most of us learned way back in algebra class that decreasing velocity will also decrease distance. It all boils down to: the slower you are, the shorter the distance traveled. This is the fundamental foundation for a short landing. There are quite a few other variables, but if you could break down one fact of short landings I think everyone can agree: slower = shorter.
This has an added benefit for taildraggers, whose center of gravity being behind the main gear creates a tendency to swivel and "swap ends," so by reducing the momentum of that mass, the danger of the ground loop is reduced.A nice example of the flare stage flown by Nathan Kurth in his Stinson 108.
The flare is the first and probably the most important part. If you've flown a steep and stable approach, then what you're really doing is trying to arrest the vertical component of your energy, and arrive at the ground at the slowest forward speed possible. I prefer the steep approach because it really allows for dissipating total energy with minimal distance covered. And it happens fast. If the approach is flown at too shallow an angle, there's less total energy to dissipate vertically, but it becomes necessary to adjust attitude and power continuously to make the spot, reducing forward visibility and using up runway to make the adjustments.
Theory is one thing, but execution is another. This type of energy dissipation is all about timing. There isn't really some magic bullet here; this takes practice, practice, and more practice. To add to the complexity, the actual inputs vary depending on weight and steepness of the decent. While the maneuver is different in every plane, the steeper and heavier you are, the more energy dissipation is required. In a heavier [light] aircraft like a Maule or Cessna 185, quite a bit of arresting energy is required to make this happen. That's where the timing is so important. Because overall energy is lower than a standard GA approach, there isn't all that excess speed to bleed off. There's really just a little bit of forward energy left before a stall.
The question becomes: Where do you get the energy to arrest your vertical component? This comes from the engine. Make no mistake; this doesn't work without the engine to help dissipate the downward vertical energy component. One of the reasons I like to advocate a steep stable approach is because it doesn't rely on engine power like "dragging it in" at high power settings does. However, when you get close to the ground there should be a thorough understanding that the engine will undoubtedly be used to arrest the descent, even if only for a second.The sink arrestor tool, AKA the throttle. Joeri van Veen @Flickr
The other half of the puzzle in arresting the descent is to initiate a flare using pitch. This may seem like what most pilots are used to as far as using the elevator, but there is a major difference: There isn't really a "round out" or "bleed off" period where excess airspeed is dissipated while burning up runway. Essentially you go from approach phase directly to the flare. This makes the timing extremely quick and important. There won't be a lot of speed or energy to bleed off if a steep and stable approach has been flown. It's just a matter of getting attitude correct for touchdown and letting engine power arrest descent in the flare. This allows you to hit your spot as opposed to float past it.
This is a very complex action, and getting it wrong can result in a few unwanted results. First, if the aircraft hasn't been slowed in the approach to a minimum forward energy then any excess energy will be transferred into floating past the intended landing spot. If the approach is steep and slow enough to require engine power (which is necessary for any measure of precision) and the timing of the flare isn't just right, the "landing" is going to be more of an impact. This could just be a bounce, or it could be worse. The reverse of this is also true. Flare too fast or high and the result will be the same: hard arrival, essentially dropping from a height above the surface. That's why practice is so important. This is a very fast maneuver and repeatedly performing the maneuver helps develop your motor learning and procedural memory. Additionally, the required inputs are different for each weight configuration and descent rate. On a gusty or thermally day in my Maule, it isn't uncommon to need nearly a full blast of throttle if gust abatement is necessary, or there's a last minute sinker close to the surface. Heavy and high in the mountains can increase the rate of descent even more. Obviously, one should try to avoid less than ideal conditions, but they're a part of flying in the backcountry and can't always be avoided. In Cubs and lighter aircraft, the timing is still important, but without all of the extra mass to arrest, they can be much more forgiving in terms of getting the timing of elevator and power correct.
A footnote to the flare portion: In most aircraft desirable for backcountry flying, there is a need for aft ballast. As these planes have been fitted with bigger engines over the years, in many cases, the CG has moved forward. I've found the need to carry ballast in many of these planes, particularly if they've been stripped down. Aft ballast is very helpful when slow and light, because it moves the CG rearward, increasing elevator authority and therefore flaring ability at slow airspeeds. Carrying gear in the back, or another person in a tandem seat aircraft is fine too. However, if it's just the pilot and half fuel, ballast makes a huge difference in the ability to use elevator for the flare.
The touchdown may seem pretty simple, but if you really look at it, the touchdown is the part that can have a massive impact on the total distance of the landing. If you've executed a steep approach followed by a big energy-arresting flare, then you're going to be in a tail-low attitude near touchdown.
This is probably where I should mention that you have the option of performing either a wheel landing or three point landing in a tailwheel aircraft, but without getting into the merits of each, it should be pointed out that there isn't a right or wrong choice. Furthermore, up until the last quarter second before touchdown, the approach and flare for each style landing are identical. The only difference is whether the stick is pushed forward or pulled back a little further. In this case both are effective, and depend on many factors (or as a response to mistimed inputs.)
In either event, the main goal during the touchdown is to establish positive contact with the ground. Touch down too hard, and it's easy to quickly initiate the start of an oscillation, where it becomes difficult to break the cycle of lift. The opposite is true if the wheels just kiss the ground and let the wings continue to work whatever lift remains. I like to touch down fairly firmly; not too rough, but certainly not a greaser. In fact, if I do grease one on I know I'm going to have to work that much harder to shorten the roll. In order to help fix whatever shortcomings I may have had at the precise point of touchdown, I like to snap the stick or yoke forward very briefly. This helps spoil whatever lift is leftover (hopefully not much.) In the video at the end of this article, it can be seen that this action is just a snap of the elevator, and typically it doesn't change attitude. It simply tells the wing that its job is over. I have to reiterate that this can be in wheel or three-point landing. A snapshot of the aircraft at this point in the landing should be of the gear firmly planted on the ground and ready for the rudder, brakes, and elevator to take over. If the aircraft has landed too rough and bounced, the goal is still the same: get it on the ground firmly. The most common mistake I see at landing is that the touchdown is too rough or smooth, and the stick or yoke is held back relentlessly in a hopeful but passive attempt to ride it out. This really prevents true control of the aircraft. Like the rest of this process, it's an uncomfortable task at first until practice creates confidence. Popping the stick forward is a fairly unnatural reaction to touching down too rough or soft. Similar to the flare, it' it's all about perfect timing.
Another way to spoil lift is to retract, or "dump" the flaps. This a much-discussed and controversial theory in some circles, and really heats up the forum topics. Here's what I have found to be true for most pilots I've instructed: There is plenty going on at this very critical moment, and grasping for the flap control is a complete distraction. For me personally, I like to dump flaps, and I find it very effective. In fact, my first paying job was flying a piggy 6,000 lb pressurized Baron into a 2,800' strip (I was young, hungry, and stupid.) The chief pilot took me out and told me: "If you don't dump the flaps in the flare you'll overrun." I'm not sure the wisdom of that whole equation, but we operated out of that airstrip for a while with that technique (I won't even go into the technique for takeoff.) That said, I often notice on the more stressful landings (short bars, windy short strips, off-camber landings, etc) that I almost never dump the flaps. I believe it boils down to comfort and physical ability. For instance, my girlfriend dumps flaps all the time in our Carbon Cub where the flaps are easy to reach, but she simply can't reach the flaps in the Maule without ducking the panel and taking her eyes off the rollout. Bottom line with my students is: If you have to think about it, or even have a slight swerve when reaching for the flaps, then don't try to dump them.
In any case, whether you've chosen wheel landing, three-point landing, dumping flaps or leaving them down, the goal at touchdown is to establish positive contact and retain as little lift as possible.
The whole reason for establishing positive contact with the ground is so that positive braking can begin. This part is going to make many a taildragger instructor cringe, and make no mistake, as an instructor this is by far my most guarded part of the landing. In fact, I don't even bother teaching this if the student isn't extremely comfortable with their craft. The reality is, if all the other elements of the landing have been executed correctly up to this point, the landing is still going to be shorter than normal. But for the shortest possible landing, brakes are definitely required. In trikes this might not be as stressful, but the nose shouldn't be forced down too hard, nor should super hard braking be initiated in soft or rough terrain. So, I put this disclaimer out there: You absolutely can land short without jamming on the brakes, but you can land shorter if you're willing to practice this technique. With my students we wade into these waters very slowly, and only after we're comfortable with each other in the instructor/student relationship. As an instructor there is almost nothing that can be done at these speeds to pull the student off the brakes if they decide give it the onion. Please understand that this a critical juncture where a beautiful landing can turn from a wonderment of aviation or an expensive, soul-gutting propstrike. Engine and propeller shops love taildraggers for this reason.
I like to use my brakes to lift my tail and turn most landings into "wheelie" rollouts. The bigger the tires, the harder you will have to brake to make this possible, and it also depends on the power of that particular aircraft's brake setup. Once on the brakes, I use very active elevator control and modulate the brakes to maintain whatever attitude I am comfortable with. Depending on the surface, I will often stay on the brakes until I'm at a full stop, using a shot of power and stick-back elevator to drop the tail. This is different for each aircraft. In tail-heavy planes this is easier to accomplish with less stress than with a light-tailed Cub or similar. Additionally, in an aircraft with 8.50 tires or smaller, I'm very mindful that I don't have the longer rotational arc in pitch as with the larger tires, and am much more reluctant to use the brakes in that manner.A CubCrafters Carbon Cub in the rollout phase, brakes in use with the tail up. Be careful!
I like tail-up wheelie rollouts for a few reasons: First, it allows me to brake hard while modulating elevator and brakes to maximize deceleration. Second, and just as important, it really increases visibility of where I'm going and allows me to dodge obstacles while keeping the tailwheel off the surface and out of harm's way. Third, it puts the aircraft in a favorable balked landing attitude without inducing gyroscopic procession (of lifting the tail) into an already stressful event.
There are plenty of occasions when a rollout with the tail down and less braking is a more appropriate action. Anytime there is soft surface that is capable of "chocking," I like to keep the tail low or all the way down. I still use brakes, but not enough to lift the tail to a horizontal position. If the ground is eroded or rough enough to catch the mains, I also find a tail-down rollout more comfortable, letting my momentum carry me through and over the "whooptie doos." Additionally, once you've picked your line, stick with it. Often people have the urge to do a quick turn just before fully stopping (I have no idea why, but it is common in my observation.) Fight that urge and come to a full stop in the area you have picked, then evaluate your situation. The bigger the tires, the easier these actions are. The longer the landing area the less important hard braking becomes. This is a delicate and sometimes unnecessary maneuver, but it is a great tool to have when operating out of short places.Heavier 4-place aircraft like the Maule will require greater care in energy management and more power in arresting the descent during the rapid flare to touchdown.
I believe that a steep, stable approach followed by an energy-dissipating flare results in the slowest touchdown possible, and that this is the safest way to operate. While this is especially true in the backcountry environment, it is applicable to most other disciplines of general aviation. Following the touchdown, the ability to use brakes and shorten the roll even more is a great tool to have, even if it is totally unnecessary for the majority of normal landing areas. This entire dance takes a great deal of practice to master, and even then it takes more practice to stay proficient. Committing these maneuvers to "muscle memory" is key; if you have to think about what you're doing in this phase, reaction will be too slow. The important thing to remember is: Excess energy produces unwanted results. Improper control inputs yield unwanted results. Slow speeds, high sink, and counterintuitive inputs are not something a pilot will be comfortable with initially. Patience, comprehension of theory, and a great deal of practice are essential to comfortably and safely flying steep approaches to precise short landings.