Short Field and Soft Field Landings
Operating from runways that aren't routine
By Budd Davisson
Ehen landing on a short or soft runway, the difference between practice and reality is that in the real world there's more at stake than the disappointment of rolling past a specific runway light, or not turning off at a designated intersection—just as is the case when taking off from a short or soft field.
For that reason, we're going to share some guidelines that can be used to help you get out with a minimum of hassle and risk. These aren't going to make you into a bush pilot, but they'll work in the sort-of-short/soft-field situations that we're likely to see.
Just like short-field and soft-field takeoffs, it's important here to remember your objectives. In a short-field landing, the goals are:
- Have zero doubt of the outcome from the beginning.
- Leave as little runway behind on touchdown as is practical, not possible.
- Hit a given spot.
- Touch down at minimum speed.
Part of the bit about knowing the outcome at the outset is recognizing both the airplane's limitations, as they relate to the field in question, and your own limitations.
The limitations of the airplane change with both with the airplane type and with the environment. A runway that's short to a Beech Bonanza is unbelievably long to a Piper Cub. A runway that is plenty long during the winter becomes a pinch in August, and runways of the same length seem to get shorter as they are moved up into the mountains of the West. In addition, a short runway with no obstacles is longer than a bigger one that has trees at the end. There are many factors that make a runway short for a given airplane, and most of those factors aren't in the POH. Even if they are in the POH, they can't be trusted.
Other factors that can make a given runway shorter include surface conditions and grade. A wet grass runway gives no braking, and a runway with a slight downgrade gets really short regardless of its actual length. If the runway is rough, then your braking is also in question and it becomes short.
The one thing that doesn't change about a given airplane on a given runway is the amount of energy that airplane is carrying on touchdown and how much resistance, as supplied by the brakes and surface friction, is available to counter that energy. At a given speed and weight, an airplane is going to have a certain amount of energy. Normally, other than burning off fuel, we can't do much about the weight, but we can definitely change the touchdown speed. This is good because speed has much more effect than does weight—the force required to stop the airplane goes up as a square of the speed. Add a little speed and the energy goes up a lot. Fortunately, the reverse is also true, which is why a major goal of a short-field landing is to touch down as slowly as possible.
There's a misconception that the proper way to land slowly is to fly final as slowly as possible. That's not entirely true. We want to arrive at the minimum safe speed (stall plus a comfortable margin for bumpy air, gusts, and you not being on your game), but that doesn't require flying the entire final that slowly. We only need to be that slow when over the threshold. During the approach, we'll start out at normal approach speed and gradually slow to a predetermined minimum speed over the threshold. As we slow down, at some point we'll see the airplane become more of a brick, and glideslope control will be slowly transferred to the throttle. Then we will use the throttle to keep the threshold/runway numbers stationary in our windshield.
Watching the threshold/numbers move is the key to our success. Just remember: If they appear to be moving toward us (or down in the windshield), we will land beyond them. If they are moving away (or up), we will land short. The goal is to hold them stationary with subtle movements of the throttle. The closer we get, the more obvious the movements become.
We've said that one of our goals is to leave as little of the runway behind us as possible, but that does not mean hanging the tail over the threshold on touchdown. Serious bush flying sometimes requires flying on the ragged edge, but few of us are likely to land on a runway that absolutely requires we use every inch. The average light airplane doesn't need much more than 500 to 800 feet to stop, so unless the runway is 1,000 feet long, it doesn't make sense to try to use every foot. Besides, trying to plant it right at the end of the runway exposes us to the risk of landing short. If you're going to make a mistake, it's better to roll off the other end at a slow speed than drop it in the trees right at the approach end.
At a minimal approach speed the airplane won't have enough energy to flare normally, so fight the urge to bring the nose up until nearly the last second. And don't suddenly chop the throttle. Gradually close it so the airplane eases onto the runway, rather than flops on and bounces. Bounces take up runway length and ruin braking.
Once down, raise the flaps to transfer all the weight to the gear and smoothly get on the brakes. Try hard to avoid sliding a tire because a sliding wheel isn't doing anything to slow you down.
A short-field landing is an "arrival." You clunk on. A soft-field landing, however, should be a gradual merging of the airplane with the soft surface. The theory is that we're going to ease our way onto the runway so gradually that we minimize the chance of the surface's grabbing a wheel.
To accomplish this we're going to fly what starts out as a normal approach, but as we come into ground effect we're going to start flying in formation with the ground, doing our best to get closer and closer to it but never touching it. Obviously, we are going to touch it, but we're going to delay it to the last second by using throttle throughout the flare.
This is really a neat game where, as the airplane tries to slow down and settle onto the runway, we keep adding just enough power to hang it in the air only inches above the runway. But we don't want to keep it there. Gradually ease the throttle back just a little and let the airplane barely touch. The throttle will stay where it is or will be slightly increased, as you try to soften the touchdown and keep the nose up. Slowly ease the power further back and let the wheels settle on the rest of the way. Then, while the power is being brought further back, gradually lower the nose to the ground—don't let it drop of its own accord. Everything we're doing here is an effort to stop the tires from penetrating any deeper than necessary into the quicksand.
Once you're down, keep the yoke back to keep pressure off the nosewheel and stay off the brakes unless they are needed because they probably won't grab evenly and will cause you to slip and slide.
Soft, short fields
First of all, there are some takeoffs and landings that shouldn't be made. When the runway is both soft and short, the best you can do is use a modified soft-field technique for either landing or takeoff, but it's a serious compromise in both cases and the ramifications should be closely considered. If it's a soft, short field and you realize on takeoff that you aren't going to make it, you have to abort much earlier because the braking won't be there to stop you. Landing in the same situation is even worse because by the time you realize you can't get stopped, you probably can't go around either.
Any runway longer than 1,800 feet generally will accommodate most small airplanes without using special techniques, as long as the density altitude isn't too high and the obstacles aren't very tall. Still, using short-field techniques can't hurt. Even though 1,500 feet isn't really short, it is short to the pilot accustomed to landing on a mile of concrete. "Short" is a personal definition. If the runway looks and feels short to you, or if it may be soft, treat it accordingly.
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 for 36 years, he teaches about 30 hours a month in his Pitts S-2A Special.