by Harold Green
In the last issue of Midwest Flyer Magazine (Feb/March 2014), we had just turned final on a windy day. Our aircraft is in the landing configuration and the pre-landing check has been completed.
There are two approaches to crosswind landings: crab/kick and slip. I teach the “slip” method, so in this article the crab/kick technique will be ignored.
This does not mean I believe the crab/kick approach is invalid. It simply means I believe the student who learns the slip technique becomes a more accomplished pilot.
It is germane to point out that the primary differences in the two techniques are encountered prior to touchdown. At touchdown and after, there is no difference. When checking pilots who use the crab method, I judge them simply on the degree of control they exercise and the quality of landing as evidenced by a respectably low touchdown force and a lack of side force.
For our purposes, the discussion will be divided into Final, Rotation, Hold Off and Touchdown/Taxi. That is, first we fly the Final Approach, and then we need to Rotate so that we can begin to slow down, followed by a Hold Off so the plane will slow down to the point that it will no longer fly and descend to the runway. Last, we actually Touchdown and then Taxi to the ramp or parking area.
When turning onto final, it is a good idea to check for possible wind disturbances. If upwind to our path, there are obstacles such as hills, buildings, etc., we need to expect turbulence. If there are significant wind gusts, the golden rule is to add one half the gust factor to the approach speed to help avoid stalling. Keep in mind that wind direction and velocity probably varies with altitude, so we will have to make continuous corrections as we approach the runway.
Final will be easier and more precise if we are aligned with the centerline of the runway. This means aligned with, not just pointing at, the centerline. As a slight modification, consider landing just on the upwind side of the centerline, as hard surfaced runways are crowned to provide drainage. This will give you a slight advantage in keeping the upwind wing down. The task now is to maintain that slip orientation until touchdown with appropriate corrections for changing winds.
It may help to imagine an extension of the centerline on the ground. Then the airplane is placed into a slip with the upwind wing down and that extension is tracked with rudder being used to keep the aircraft’s longitudinal axis pointing along the centerline. The task now is to maintain speed, descent path and track. Focus on those elements is required to do this. The more experience you have, the less difficult it becomes.
Constantly referring to instruments makes the task more difficult. If you can hold speed and attitude mostly by visual reference, you have a leg up on the process.
With any landing, it is necessary to be aware of where you will touch down. Same rules apply as in a non-crosswind landing: The point on the ground that appears not to be moving up or down in the windscreen will be the point at which you would touch down with no flare. The airplane will have its upwind wing down to keep the airplane tracking with the centerline and, of course, opposite rudder will be required to hold the track. During descent on final, wind direction and velocity changes will require a varying amount of slip and hence rudder.
The ailerons may be thought of as sliders and the rudder pedals as pointers. That is, ailerons are used to keep us aligned laterally with the centerline extension, and the rudders used to keep us pointed along that extension. Flaps should be used only as necessary because they will cause difficulty in maintaining track alignment and can cause loss of rudder control in even moderate crosswind speeds.
A typical question from the beginning student is: “How much control should I use?” Obvious answer:” As much as it takes to keep the airplane in the attitude you need.”
The landing becomes much easier if the pilot sets very tight standards on maintaining alignment with the centerline. This alignment should be as perfect as the pilot can make it, and can hold it. If that alignment cannot be held because the controls have reached their stops and the airplane is not in the necessary attitude, go around and re-think the situation. Inability to maintain track and heading because the controls are at their limit indicates that the airplane’s capabilities are being exceeded and it is best to find an alternate landing site.
Typical errors during final are: Failing to track the centerline extension and allowing airspeed to fluctuate.
Eventually we begin rotating for the touchdown and several things happen.
First, the airspeed may be high because of the gust factor. This means it takes longer to slow down.
Second, as the plane slows down, the wind becomes a greater percentage of the airspeed and hence has a greater effect on path and altitude. Therefore, the higher the round out is begun, the longer the airplane is exposed to possible disturbance by the wind, and the more attention is required to maintain the desired path.
Third, the lower the altitude, the stronger the ground effect. However, ground effect will cause the lift/drag characteristics of the plane to change and the pilot must compensate. In general, ground effect will increase lift and hence increase the time to slow down even further. As an additional complication, the wind speed and direction will also change when within a few feet of the surface. Generally, velocity and gusts will decrease the closer to the surface we are.
It is imperative that the pilot maintains aircraft control until the airplane is firmly on the ground.
The pilot naturally wants the airplane on the ground because this slipping stuff is not comfortable, there is a natural concern about causing the wingtip to hit the ground, and the pilot is tense. Don’t let this get to you. Just keep flying the airplane and it is going to land just as it does without a crosswind. The pilot’s job is to just maintain the proper control inputs to allow the airplane to do just that, but when it is ready.
At this point the airplane should be held off and prevented from landing until it is ready. Flaps can prevent an airplane from properly maintaining heading until touch down due to the rudder’s inability to overcome the drag factor created by the flaps. Therefore, flap use should be limited to the extent possible. In addition, in really strong crosswinds, carrying a little power can help because among other things, the increased airflow over the rudder increases its ability to counteract the yawing tendency of the nose in the slip.
There are two very common concerns when learning crosswind landings. First, a very common – indeed almost universal – concern on the part of students is a reluctance to maintain one wing low out of fear that the wing will hit the ground. The angle that will do that is very pronounced and you are not likely to get the airplane banked that far. If this is a concern, it is best to find an instructor to demonstrate the degree of bank, which is acceptable.
Typical errors during Hold Off are: Failure to use rudder to maintain heading along direction of travel; failure to correct for side drift with ailerons; and rotating too high, exposing the airplane to extreme wind conditions as it slows.
When approaching touchdown, do not try to force the airplane onto the ground before it is ready. It is best simply to let the airplane decide when it wants to land, just as in a non-crosswind landing. Just maintain the attitude until the airplane naturally wants to touch down. Once the airplane is down, it may be necessary to hold it onto the ground with forward elevator and upwind aileron in a tricycle gear plane. Tailwheel airplanes need to keep the tail up as long as possible in a wheel landing, and once the tail is down, the pilot needs to taxi very slowly with plenty of aileron and, if necessary, brakes.
The airplane should not be allowed to touch down with any side motion in order to protect landing gear, tires and in extreme situations, prevent the airplane from becoming uncontrollable and tipping.
The longitudinal axis should be pointing in the direction of travel. If your airplane has retractable gear, be especially mindful of the side loading on the landing gear. The tricycle gear airplane is nothing but a three legged milk stool, and in some situations, very subject to tipping, particularly if the wind gets under the upwind wing as you turn across the wind. A tail dragger in a three-point landing can easily be ground looped in this situation and, if in a wheel landing, it can still easily enter a ground loop as it slows down.
In a good crosswind landing, the upwind main wheel should noticeably touch down first. It’s alright to keep it on one wheel for a bit. Once on the ground in a tricycle gear plane, it may be necessary to hold the plane down with forward elevator pressure and upwind aileron. With a tail dragger, the best advice is to fly the plane even on the ground, and when taxiing downwind, keep the tail down with elevator. A crosswind takeoff run is initiated with full upwind aileron, which is removed as speed builds up. In a crosswind landing, we begin with enough aileron to keep the upwind wing down and end up with full upwind aileron as the landing roll ends.
As the airplane changes heading when exiting the runway, revert to the taxi techniques discussed in the preceding article. Remember, it is necessary to fly the airplane until it is firmly attached to the ground or is totally undercover outside of the wind. Unfortunately, the plane doesn’t know whether it is flying or the wind is blowing.
Typical errors at touchdown are 1) Failure to hold the upwind wing down. 2) Failing to hold the airplane on the runway with elevator. 3) Applying brakes too early and too vigorously. 4) Touching down with side motion. 5) Touching down with the airplane not pointing in the direction of travel.
If you feel uncomfortable in crosswinds and want to increase your ability, practice on a day when you know you can handle the situation. Then, as you gain confidence, go out on days when the wind is a little stronger and keep ramping it up to increase your comfort zone. If there are no crosswinds at your airport, you can usually find an airport where the wind and the runway do not line up.
You might also consider conducting all but the touchdown and flying down the runway a few feet off the surface, holding the slip attitude. Then, as your comfort level increases, just land the beastie!
Most air traffic controllers will be glad to assign you a crosswind runway if you ask. Also, remember there is no fault in deciding to go around or even to a different airport if things get too wild for your capabilities.
You can avail yourself of the services of a flight instructor to push the envelope ahead even faster. When all is said and done, there are few things more satisfying than a “squeaker landing” when the wind is 15 or 20 knots, gusting to 30, and lesser beings are sucking down coffee at the airport while watching you put the bird through its paces. And if you just happen to keep the plane up on one wheel to almost the taxiway, that’s not bragging…. It is just maintaining competence.
EDITOR’S NOTE: Harold Green is a Certified Instrument Flight Instructor at Morey Airplane Company in Middleton, Wisconsin (C29). Email questions or comments to: firstname.lastname@example.org or call 608-836-1711 (www.MoreyAirport.com).