Airplane Crosswind Landing

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It seems that not too many people pay much attention to slips anymore. I guess the advent of flaps and spoilers has caused the need for the slip to be pushed to the rear of the list of things some pilots believe they ought to learn. However, they still have a very real place in the mind of the complete pilot. The FAA has only recently reintroduced the forward slip to a landing as a required maneuver for the private pilot checkride.

Some say, “If you have flaps, you don’t need to slip, and anyway, it’s unsafe to slip with your flaps down.” To this I politely say, “Nonsense.” Unless your particular aircraft is placarded against slipping with flaps, go ahead. And even in the aircraft that are placarded concerning slipping with flaps, most don’t prohibit them. The placards usually say, “Avoid slips with flaps extended.” Many aircraft flight manuals don’t mention the fact one way or the other. If your aircraft is prohibited from slipping with flaps, don’t. Otherwise, why not? It just might get you into a field you might have otherwise overshot. It can be especially true in an emergency situation.

Generally, there are two varieties of the slip: the forward slip and the side slip. Although the two are very much alike in the manner in which they are executed, the forward slip usually requires much larger doses of control input. The one facet in which both are alike is the fact that you must have your controls crossed. Crossed controls means you hold your ailerons in one direction and rudder in the other —something most pilots find rather uncomfortable until they have executed many slips.

If you have any wind, the slip should be done into the wind. If the wind is from your left, the left wing is the one put down. But, if all you do is put down the left wing, what will happen? You’ll turn left. To keep the aircraft from turning, add opposite rudder. Now you are cross-controlled —slipping.

To put these slips to work for you, you need to know what each one is for and what the desired results should be. The forward slip is used mainly for altitude loss. The sideslip is used to align the aircraft with the runway and to touch down in a crosswind.

The forward slip
Let’s set up a situation where both types of slips are used on one final approach and landing. Throw in a crosswind to complete the setup. You have turned from base leg to final approach and find yourself very high. You are landing on runway 18 and the wind is from 120 degrees at 10 knots. You already have full flaps and power at idle, yet you are still going to overshoot. Now what? If you are very high, you will have to go around; however, if you are only a little high, the forward slip just might be the ticket.

Lower your wing into the wind as you apply opposite rudder. In this case, you need to lower your left wing and add right rudder. You want the nose to swing past direct runway alignment, say 15 to 20 degrees to the right. You will still be tracking straight down the runway, but your nose will be pointing at a heading of about 200 degrees or so. This is the signature of a forward slip: Your heading changes while your ground track remains the same.

Now comes the important part: Don’t let your airspeed build up much over approach speed. If you do, all the gain of the slip will be lost because once you get down, you will have to bleed off the airspeed and you will float much farther, negating the advantage you gained from slipping.

Continue to slip until you are down to the point where you reintercept your glide path. Then, come out of the slip and proceed with your approach. You get out of the slip by reversing your aileron and rudder, bringing your aircraft back to level flight with the ailerons, and using left rudder to swing the nose back to direct runway alignment. Most likely, since you have a crosswind, you should continue to bring your nose past direct runway alignment into a crab condition to take care of the crosswind ground track.

Now, you have lost the unwanted altitude, are still tracking straight down the runway, and will be ready to complete the crosswind landing.

The sideslip
The crosswind landing is accomplished using the sideslip. In this slip, the longitudinal axis of your aircraft remains parallel to the flight path. In the sideslip, lower your wing into the wind and add opposite rudder as you did in the forward slip. Add only enough rudder to maintain your track straight down the runway. You sort of lean into the wind like you used to do when you rode your bike in a strong crosswind. You still go straight but are banked to correct for the crosswind. It probably will take a little practice before you become proficient and comfortable with sideslips and remember to use the controls as you need them. You can’t just put the wing down a certain number of degrees and leave it there because the wind will probably increase and decrease in intensity. So use whatever it takes to hold your runway alignment.

The crosswind landing is accomplished exactly as any other landing, except you keep your sideslip throughout the approach, flare, and touchdown. Remember, after touchdown, you’re not through yet. Maintain your windward wing down and use your rudder as necessary to maintain runway heading. As you slow down, add more aileron into the wind because the controls become less and less effective as your speed slows. In fact, as you reach your slowest speed, you will want to have full aileron into the wind to correct for the crosswind, just as if you were taxiing. By the way, that is taxiing.


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