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Are you taking off from a grass or gravel runway? Is your hard-surfaced runway covered in snow? Then it's time for you to show off your soft-field takeoff skills. Here's how you'll do it.
How is a soft field takeoff different than a normal one? It all comes down to one goal: transferring your aircraft's weight from the wheels to the wings as quickly as possible.
Why? By lifting off as quickly as possible, you eliminate drag from grass, sand, mud snow, etc. And that's important, because excessive drag on a runway can dramatically increase your takeoff roll. Just look at this example:
Drag might not be the only reason you want to use a soft field technique. If you're on a very rough surface, a soft field takeoff can prevent your teeth from shaking out of your head, or worse, you damaging your nose wheel on the takeoff roll.
So what are the steps to a successful soft field takeoff? Let's break it down into three phases: takeoff roll, liftoff, and initial climb.
First off, when you're taxiing for takeoff on a soft surface, you want to keep your airplane moving at all times if possible. Why? If you come to a complete stop and your runway is soft enough, your wheels could sink into the runway far enough for you to get stuck. And there aren't many more ego-deflating things than calling for a tow out of the soft grass or snow because you're stuck. You also want to keep full back pressure on your yoke, to keep as much weight off your nose as possible.
You'll want to have your flaps configured for your soft field takeoff as well. This depends on your airplane, and you should always follow your POH, but as an example, the Cessna 172S recommends 10 degrees of flaps. By extending flaps, you increase lift, as well as your ability to get off the runway more quickly.
When you're lined up with the runway, you want to smoothly add full power, as well as back pressure on the yoke (many airplanes suggest full back pressure initially, but again, it depends on your plane). This does two things: 1) it reduces the weight on your nosewheel, and the stress it receives from the soft/rough field, and 2) it allows you to lift off as soon as possible.
During the takeoff roll, your nose wheel will lift of first. As it comes off the ground, you want to start reducing back pressure slightly on the yoke to prevent your plane from lifting off too aggressively. As you slowly reduce back-pressure, you want to try to maintain the same nose-high attitude throughout the takeoff roll, and let the airplane fly itself off the runway.
As you lift off the runway, you need to keep in mind one very important thing: ground effect. The only reason your airplane is able to lift off the runway as such a slow speed is because of ground effect, and it also means that your airplane isn't ready to continue climbing - at least yet.
When you lift off the runway, you need to lower your aircraft's nose and fly in ground effect while you accelerate to a safe speed: either Vx or Vy. This is one of the most challenging parts of a soft field takeoff - if you relax your back pressure too much, you can settle back down onto the runway. If you don't relax it enough, you can climb out of ground effect, and them come back down to the runway because your airplane isn't flying fast enough to continue climbing outside of ground effect.
As you accelerate to Vx or Vy in ground effect, you'll also find that you need continuously relax back pressure (or depending on your trim and airplane, increase forward pressure) on the yoke to remain in ground effect. This is something that takes a little practice to perfect, and the more times you do it, the better you'll get.
Now for the last part of the takeoff: initial climb. Do you have an obstacle at the departure end of the runway? You'll want to start your climb when you reach Vx. No obstacle? Then Vy is for you.
Once you've established a positive rate in your climb, it's time to clean up the airplane. Retract your flaps (and gear, if yours are retractable) according to your POH. Then, take a minute to enjoy the fact that you just accomplished a flawless soft field takeoff.
Soft field takeoffs tend to be one of the more challenging takeoffs. So where do things go wrong? Here are a few common problem areas:
If you know the common problems, you're already a step ahead in executing a good takeoff. And now that you know how to make it all happen, it's time to get out to the airport and log some practice takeoffs. Even if you're an experienced pilot, it's always good to brush up on your next flight. Besides, what better excuse do you need to get out to the airport?
Colin is a Boldmethod co-founder, pilot and graphic artist. He's been a flight instructor at the University of North Dakota, an airline pilot on the CRJ-200, and has directed development of numerous commercial and military training systems. You can reach him at email@example.com.