Crosswind Landing Instruction
To begin with we must assume that the student pilot has flown the pattern in such a manner as to arrive on the final approach with appropriate flaps for wind angle and velocity, on glide slope, and on airspeed.
The basic training exercise for the crosswind landing is the Dutch roll. The presumption is that mastery of the Dutch roll has prepared the pilot to keep the aircraft parallel to the runway at all times on final, while maintaining runway alignment with left-right side slips as required. My preference is to maintain a constant airspeed regardless of the slip. The slip redirects the pitot tube so that the relative wind pressure is at an angle. There is no air flow in a pitot tube. This means that the greater the slip the greater the forward yoke pressure.
In the ideal approach the wind would remain as a constant. This would mean that the slip angle and required rudder would remain constant. It doesn't happen. The wind is a constantly changing approach factor both as to angle and velocity. This means that the pilot must constantly adjust aileron, rudder, and yoke to maintain a stabilized approach with constant heading, runway alignment and airspeed. The essential skill is the previously mentioned Dutch roll and anticipation of changing conditions before radical adjustments are required. I very much recommend that extended straight in approaches as a planned training exercise to give smoothness to the control applications.
The wind velocity usually decreases during the descent so that less cross control application is required as the flare approaches. The actual flare is much as with any other landing but since generally less than full flaps will be applied greater care must be used to avoid ballooning. At this point full attention must be paid to prevent any sideways movement of the aircraft. Landing gear are exceptionally strong and resilient but they are most subject to damage when side loads are applied.
If everything goes well the touchdown is made at minimum speed on the upwind main wheel with the nose wheel and downwind main still flying. This configuration can be bothersome to passengers and should be explained as normal before the landing. The wing low need not be of concern if the aircraft is kept going parallel to the runway centerline. As the aircraft decelerates the yoke should be held ever more into the wind and back. The downwind tire will touch to be followed by the nose wheel. Use rudder as required in holding a straight course down the runway after the first touchdown. Correctly done you are now in the proper configuration for taxiing on the runway.
A crossword on landing will increase stopping distance. The tire surface contact area provides only so much friction. In a crosswind this total friction is divided between the effect of the crosswind creating side-load friction and the braking friction working against the forward momentum. For this reason expect crosswind rollouts to be longer.
One Wing Low Landings
Half a Dutch roll is basic to all wing low/opposite rudder crosswind landings. It is a matter of pilot judgment to decide what to do if rudder authority is insufficient to allow the pilot to hold the nose aligned with the runway. In my experience I have applied full rudder and wing low and then eased off with rudder if the situation allows. Should the rudder lack sufficient authority, I will lower the nose or add power to the point where full rudder application will straighten the nose. I will increase my approach speed as needed so long as runway length will be sufficient to let me float until this excess speed is lost in the flare.
I have never been concerned with excess bank angle because the closer the tip gets to the surface the greater the resistance due to ground effect. The primary concern is to keep the nose straight with the runway centerline. I do not believe you can make the tip touch so long as the nose is straight. I have landed Cessnas in 45 knot 90-degree crosswinds without touching the tip. Once on the ground, I always hold the yoke full over into the wind and it often seems I will catch a wingtip but I have always backed off without touching the ground.
I have found that even at airports with multiple runways, ATC is willing to allow those who ask to use the crosswind runway so long as traffic conditions will allow. I have used the crosswind runway at non-tower airports with as many as four other aircraft in the preferred runway pattern. With proper radio procedures they have spaced out so that my student and I have been able to get the practice required to give the student the confidence that was previously lacking. It is surprising how easy it is the handle crosswinds once you have extended your personal crosswind limits up into the 20-knot region.
Just the other day I took a student into some crosswind landings at a non-tower airport. Student made four landings where touchdown occurred power off and near the numbers. I did one to demonstrate that the student was working too hard to keep runway alignment and drift countered. The last two approaches I deliberately set up the situation were the touchdown was half-way down the 4000' runway abeam a small grove of trees. All at once the student's landings became more difficult. The trees changed the previous steady wind into a series of swirling gusts. The difference in the landings showed that more practice is needed. There is no time to add speed, you have to land with what you've got or go around.
Other Opinions:
Opinion
The rate of (aileron) reduction depends on the absolute magnitude of the crossword component and the developing forward speed.
Opinion
I have a different viewpoint. I do not want anyone that I have taught to arrive at a destination with crosswinds that they have not been exposed to.
Opinion
My suggestion to you is to get with your instructor on the windiest day you can and practice x-wind takeoffs and landings to determine what your maximum capability may be.
Crosswind Landing Skills
Were I to have all the control I wanted in the teaching of crosswind landings I would make the first instructional requirement to be that they should be taught in sailplanes. The necessity fomented by only getting one shot at a narrow runway would be sure to focus a student pilot's attention. Ground reference maneuvers in airplanes do not provide the realism that is required for students to sense winds in the pattern. The crosswind landing begins on the downwind. Only by flying the appropriate (wind corrected) downwind can the base and final be readily adapted to the wind conditions. The other legs of the approach only compound the problems of an inappropriate downwind.
In very light crosswinds of 5 kts or less the use of full flaps should not be a problem. However, I find that most students are not able to detect, counteract, or otherwise compensate for the subtle effects of a light crosswind. Dutch roll weakness seems to be the culprit. I would suggest that under light wind conditions a student should be set up on an extended final approach to do the following. Practice side slipping the aircraft left and right across each side of the centerline. Next sideslip to each side while stopping momentarily on the centerline to assure that the nose is being kept parallel and approach speed maintained. This could be done all the way to the landing as a confidence builder.
Crosswind landings can best be practiced where parallel runways exist or where left/right patterns can be flown to the same runway. It is very important that both left and right patterns be flown to teach the differences in planning for the crosswind, downwind, base leg, and final. Skill in getting the wing low and opposite rudder applied is related to how well Dutch rolls can be performed. Initial practice can be with light crosswinds but true confidence and capability requires practice in winds of 18 kts or greater. Towers are usually obliging in the use of crosswind runways.
The velocity of winds usually decrease with altitude. This is true even for winds below 1000'. If the indicated approach speed is held along with power and flaps as constants in the approach, the variable becomes rudder and ailerons. Rudder is used to hold the nose parallel initially and varied as aileron inputs are used to maintain runway alignment. Any change in the rudder requires a change in the ailerons and vice versa. While this is uncoordinated flight, there is coordination between them predicated upon keeping the aircraft nose both straight and aligned with the runway. In this configuration the landing touchdown will be on the upwind wheel first, then the downwind wheel and then the nosewheel.
Every pilot flying has assumed a degree of responsibility for his presumption of ability and skill in making crosswind landings. As a pilot you are expected to have read and understood the significance of the demonstrated crosswind capability of your aircraft. This means that at the time of certification a certain velocity crosswind existed. At this velocity an average pilot would be able to land. Beyond that velocity you should be a better than average pilot. Whenever you taxi, takeoff, or land in conditions that exceed the maximum demonstrated crosswind component you become a test pilot. FAR 91.13 applies.
Knowing when a wind exceeds your piloting capability is usually not discovered until too late. You, as a pilot can determine the wind by entering the wing-low opposite rudder approach early on. If the flight path cannot be stabilized on the approach then a decision to go-around is a good one. Making the go-around decision before the press of circumstances adds additional problems, requires that the pilot think ahead of the airplane. An early go-around is an indication that the pilot is ahead of the situation and ready to select a more favorable landing situation. Turbulence and wind shear are to be expected when winds are active.
The wing-low opposite rudder is an uncomfortable configuration for most pilots. Being proficient in the Dutch roll makes for greater proficiency and comfort. It is proficiency in the Dutch roll that makes getting the control input needed automatic. Only frequent practice will maintain proficiency.
As an instructor I seek out crosswinds. I don't want a student to be faced with wind conditions that have not been encountered during dual flight. Each pilot will need to recognize his limits in a particular aircraft. The 'demonstrated' limits in the POH are not the limits of a proficient pilot.