Page 4.71 ( 8814)
Landing in Winds
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...Downwind Landing; ...Downwind in a Crosswind; ...Base in a Crosswind; ...Demonstrated Crosswind Capability; Dutch roll; Learning the Dutch roll; Why the Dutch Roll; ...Crosswind Landing; ...Crosswind Landing Instruction; One Wing Low Landings; Other Opinions; ...Crosswind Landing Skills; ...Crosswind Proficiency; Crosswind Capability; ...With a Crab and a Kick; ...Landing in Turbulence; ...Unusual Wind Landings; ....Rules of Thumb for Landings; Risks Related to Landings; When Things Go Wrong; Wind Effects; Crosswind Landing Notes; Crosswind Taxiing; ...Phil and Dudley on Winds; ...
The entire downwind approach, even with full flaps, is unexpectedly flat. Flying the familiar pattern results in a go around. The aircraft will be moved by the air mass too tight in the pattern. Trying to adjust the approach and apparent ground speed so that it is "normal" will not work. Further, if we are not in the habit of making full stall landings and even if we are, the landing roundout, flare and roll will require much more runway length than we would ever expect. It is this unexpected distance that often makes the inexperienced pilot try to force the airplane to the ground before it is ready. The resulting flat or hard landing extends the distance required even more. The controls on the ground must be held correctly especially if there is a quartering tailwind during rollout. If you expect to be going into a one-way airport be sure to get some downwind practice first.
The difficulty with downwind landings is the conflict of previous performance and perceived performance. We are used to landing into the wind and the reversal of wind makes things happen differently. Pilot judgment is impaired by the perplexing unfamiliar ground speed being greater than airspeed. By failing to fly an exceptionally extended downwind the full flaps, power off, and minimum approach speed does not get us down. The C-150 requires at least 50% more runway with a 10-kt tail wind added to the normal approach speed. Busy airports frequently will maintain the use of a runway after the winds reverse direction because of traffic or noise considerations. Some airports have a calm-wind runway. This calm wind may exist at ground level but not infrequency the entire approach will be with a tail wind. The IFR straight in ILS with a tail wind may be your only option someday or some night as preferred to circling.. The increased ground speed caused by the tail wind will make for a very flat approach and a long landing roll.
While the inadvertent downwind landing may occur during near calm conditions, it may be required at a one-way airport. This is an airport for which there is only one landing direction regardless of wind. Ruth, the northern most airport on the S. F. sectional is such an airport. This landing as well as cross wind landings, can be practiced at a non-busy tower airports.
ATC is authorized to use any runway when the 'calm wind is less than five knots where it is operationally preferred or requested. ATC will advise of the downwind condition. Pilot requests are usually honored by ATC.
Downwind in a Crosswind
The beginning of a good crosswind landing is determined in how well the pilot maintains the downwind leg a desirable distance from the runway. If the left pattern downwind crab is toward the runway then the right pattern downwind crab must be away from the runway. The key to avoiding any problems in the turn from base to final is dependent upon not letting the downwind track shorten the base leg. The decision should be to keep your downwind legs very wide for all crosswind landings. Skill in maintaining pattern spacing is acquired during ground reference training. A wide base lets you adjust your turn to final if high or low. Suggest you draw it out on a piece of paper.
Base in a Crosswind
Whether a crosswind adds or detracts from your base ground speed and track, it is important that you plan accordingly. The base-to-final turn in a crosswind requires specific procedures to allow you to smoothly align the plane with the runway. If the cross wind is adding to your ground speed, then the turn will have the correct wing low and require opposite rudder to align the nose. If the crosswind is slowing your ground speed, it will be necessary for you to reverse the turn bank immediately on final and apply opposite rudder for alignment. Because the turn to final in each case is so different, it is important to practice both left and right pattern landings in the same flight and wind conditions. Anytime the aircraft is in a cross-control configuration on final, significant forward yoke pressure will be required to maintain the indicated approach speed.
Even when the base to final is properly turned for runway alignment, there is considerable difference in how the turn concludes. Unlike most turns that are completed with the wings level, the crosswind landing turns from base to final are completed with a wing low and opposite rudder to align the nose parallel with the runway. If the base leg has a tailwind adding to your ground speed the turn to final requires only that the opposite rudder he held for nose alignment while the wing continues to be held low into the wind. If the base leg has a headwind the turn to final must be quickly reversed to the opposite bank from entry while the rudder is depressed to keep the nose straight with the runway. The more constant the airspeed the more consistent will be rudder pressures and aircraft performance. Any time the aircraft is in a cross control configuration on final, significant forward yoke pressure will be required to maintain the correct indicated approach speed.
Demonstrated Crosswind Capability
When an aircraft is certified by the FAA, it includes a demonstrated crosswind capability. The capability is based only on the winds available for that time and day. Some capabilities are based on relatively light winds. This means that an average pilot with average competence will be able to land without difficulty. This is a very poor method of determining the flying limits of an airplane.
Students should expect to have trouble with all the variables of airspeed, wind velocity, bank angle and rudder application when learning crosswind landings. Of all standard flight maneuvers the crosswind landing requires the greatest variety of contradictory control applications. Only mastery of the Dutch roll prepares the student for what is going to happen. The Dutch roll removes the intellectual process from the uncoordinated used of controls. If you must think of what to do, you will always be behind the plane.
The crosswind slip to a landing uses the opposite rudder, as applied to keep the aircraft centerline parallel to the runway centerline. The opposing aileron is used to tip the wings so as to slide and maintain the aircraft centered on the runway approach line. The greater the crosswind component the more flaps application is reduced.
Once the crosswind component exceeds that which was used during the certification demonstration the pilot is advised to adjust the use of flaps and speed to suit the conditions. Any time the full application of the controls and increased speed is unable to maintain directional control the go-around is the only option.
Low touchdown speed gives each knot of crosswind additional effect so that additional aileron and rudder deflection--and more bank angle-- is needed to get the slip angle needed to hold runway alignment. Whatever deflection is needed on final approach is only 2/3 of what is needed at flare and touchdown because of slower speed.
A student would be ill advised to self-instruct crosswind landings. Wind gusts can occur that will make the go-around as the only viable option. Without experience a student is apt to be too late with too little.
The "Demonstrated Crosswind" is a meaningless certification requirement indicating that on the day the aircraft was FAA certified that was the maximum wind available. The maximum wind I can land in is the one in which I can keep the wing down with the aileron for runway alignment and the nose straight with the rudder. If I run out of rudder authority I will increase airspeed. So long as I keep the nose straight with the rudder I do not worry about how close the wingtip is to the ground.
Many years ago there was an airport at Antioch, CA near the junction of the Sacramento and San Joaquin rivers before they join to enter the San Pablo Bay northern end of San Francisco Bay. It was relatively narrow, short, and the favored direction had considerable down slope. I used this airport as a landing graduation standard for my students. On this occasion, my student was Jay Spangenberg in his early 20's. Of interest is that he was the grandson of Mr. Taylor, designer of the Taylor aircraft line. I had Jay take me to Antioch airport for his high-wind graduation. Wind was strong at 90-degrees to the runway. Jay did everything he could to keep the aircraft aligned and the nose straight for a landing without success. He executed a go- around. I told him to let me demonstrate how I should be done. I did no better than Jay and made my go- around. Good instructor lesson.
A few years ago at Concord, CA, my home field my student and I heard a young lady advise ATC that she was unable to land on the assigned runway under the prevailing wind conditions. She was offered taxiway Charlie which during the war had been runways 24 and 6. She readily accepted, as did we by request. Landing on 24 gave us a ground roll of less than 150 feet, the width of an intersecting runway.
Only last week did I hear a pilot express surprise that when I specifically requested a crosswind runway from ATC. He asked ATC if he could ask for any runway he wanted. ATC's response was that you can always ask but you may not get it.
Has been defined as a second order composite stability characteristic that results for the lateral-direction cross-axis coupling of two separate responses to a sideslip. Since there is a coupling between the roll axis and the yaw axis is often considered as a lateral-directional oscillation. Actually the Dutch roll is a relatively easy to control rocking of the wings while holding the nose straight with the rudder. Undesired, the Dutch roll is a nuisance that can occur in turbulence or on an instrument approach. The term is derived from the rocking and rolling motion of 15th century Dutch sailing ships.
What can create a problem is the fact that it is an uncoordinated maneuver. You can create a Dutch roll problem just by trying to fly with only the rudder. While trimmed for level flight, displace the rudder and then put your feet on the floor. The aircraft will waver back and forth and finally return to level flight. Doing the same thing while trimmed at approach speed will aggravate the Dutch roll and make it take longer to smooth out. Do this again but try to use the ailerons only to hold a heading. The adverse yaw of the down-deflected aileron will cause the aircraft to perform Dutch rolls.
Dutch roll introduction:
Students to first plant feet on the floor. Sight a reference point, straight ahead or a heading. Rock the wings back and forth between about 45-deg bank left and right. Hold the nose on the reference point or heading. No rudder. Now try it with rudder. Rock back and forth and back and forth, rhythmically for a minute using the rudder.
A student typically uses on the wrong rudder and wrong pressures in the beginning. It will take a few sessions to get it right. When the Dutch roll finally falls into place you have mastered the basic control skill required for doing crosswind landings.
Learning the Dutch-Roll
UNCOORDINATED FLIGHT---A NECESSARY SKILL
While the controversy continues over spin training, I feel that a much more practical and useful flight skill is being neglected. I write thus of the Dutch-roll. I suppose that just as much of our aviation language originated from naval terms, the origin of the Dutch-roll could have come from the peculiar sideways shift of the stern of an apple-bowed caravel (Dutchman) when running before a following sea. As the stern was lifted by the oncoming wave it would swing to one side, the hull would roll as the swell passed, and the stern would swing back onto the course-line as the breaker moved under the bow and the hull rolled upright.
In an aircraft, especially those with V-tails, it is a tendency for the tail to wander off the line-of-flight far enough to generate a straightening force, but overshooting the correction only to repeat the excursion on the other side. If accompanied with a pitch variant, the tail may oscillate in a circle. The Dutch-roll in ship and aircraft is an undesirable characteristic.
The basic Dutch-roll consists of rocking the wings with the ailerons smoothly through a series of 10, 20, or 30 degree banks while keeping the nose on a point or heading with the rudder. If done while the aircraft is climbing most of the rudder application will be more or less right rudder with an occasional tap of left rudder. This does not detract from the value of the exercise.
To the student pilot, to whom the coordinated use of rudder and aileron has become a sacred ritual, the contradictory control pressures required for the Dutch-roll ranks as sheer heresy. The control pressures required equate with patting the head while rubbing the stomach. The skill acquisition compares with that of roller skating. It is best not to intellectualize it. Just do it until all by itself it seems to fall into place. Remember when you learned to skate?
Just as the four basics are skills essential in normal flight situations, so is the Dutch-roll an essential additional skill for successful crosswind landings and use of the rudder. In the off chance that the reader may be unacquainted I will endeavor to describe the maneuver and suggest an instructional sequence.
The Dutch-roll can be flown level, climb, or descent. You select a point or heading and try to keep on that heading. Beginners seem to do the series of banks too quickly. This increases the yaw effect and makes necessary abrupt usage of the rudder. At a slower pace the rudder use can be better anticipated. If the nose swings the rudder is being misused. Start over. The nose should not move during the banks. Maintain a constant airspeed. The rudder must be applied or relaxed sometimes in anticipation and at other times in conjunction with the ailerons.
A suggested instructional or practice sequence would be to use the climb time from pattern altitude to cruise altitude. This time is often under utilized and the Dutch-roll serves to clear the flight route. The student can begin with a series of rhythmical 10 degree wing movements while the instructor applies rudder to maintain heading. It is vital that airspeed be maintained relatively constant so that rudder application and effect will also be constant. Then the roles can be reversed between student and instructor. The third step would be the student performing both functions with the instructor monitoring. If, for any reason, banks and nose movements become erratic--start over. See, just as in roller skating. It seems to be best to initiate the first banking of the wings to the left followed quickly with a solid application of right rudder before the nose has a chance to swing.
The left turning-factors of the climb is a constant that requires right rudder. The banking causes yaw which is a variable depending on amount and quickness. When the bank begins toward the right the rudder pressure is gradually relaxed but not removed because of the left turning-factor and adverse yaw in climb. The banking movements must be continuously smooth and rhythmical, as in waltz time. All efforts to control heading must be done with rudder while the banks are maintained in rhythm. Rudder amounts and timing of release or application is done in anticipation of heading changes.
The student will experience extreme frustration with this exercise in the beginning. As the student becomes visually aware of the nose on the horizon and how rudder is a control he will improve. It is vital that expectations of proficiency be planned over at least five flights. If air sickness is a problem, approach the exercise in gradually extended time periods from twenty seconds to three minutes. The most common difficulties seem to be making the banks too quickly and of unequal angle, holding the yoke tightly, not making airspeed adjustments, not recognizing heading changes, belated rudder applications, and attempting to salvage a blown exercise. If the nose begins to wander, start over.
Even though we are in uncoordinated flight there is still a required coordination between foot and hand, rudder, aileron, and airspeed. Coordination, even in uncoordinated flight, is a basic skill required for slips and crosswind landings.
Now what do we get from this. We get a pilot who can enter final for a crosswind landing with one half of a Dutchroll and the visual coordination skills required to maintain runway alignment, the nose position and the airspeed. The pilot can do this with those Dutch-roll skills that enable him to anticipate rather than react. He is ahead of the plane, not behind. If, because of wind velocity and direction or control problems, the half Dutchroll cannot be held on final--GO-AROUND.
Why the Dutch Roll
There are two ways, actually three ways, to perform crosswind landings. The oldest method required that the aircraft fly the whole final in a wind correcting crab until in the flare. At the flare the nose would be rudder aligned with the centerline and a wing dropped into the wind for touchdown. Exquisite timing made this work very well. Anything less would (could) put damaging side loads on the landing gear.
The FAA preferred crosswind landing uses a cross controlled approach in which the nose is aligned with the centerline while a wing is lowered into the wind to correct for any crosswind. On the entire approach, flare, touchdown and rollout the nose is kept straight and the yoke into the wind. The third way is a combination of the two with the wing low initiated before the flare.
The Dutch roll is the basic training maneuver that prepared the pilot to enter into the wing-low/nose-straight by 'doing what it takes' without conscious intellectual involvement. My best analogy is the art of roller skating.
The actual Dutch roll is a process of using uncoordinated applications of rudder and aileron in such a manner as to fly a specific heading without change while at the same time making the aileron changes necessary to offset any existing crosswind and it's variations.
Simply put, you practice rocking the aircraft wing down to wing down the same amount to each side while using the rudder to prevent ANY yaw. If yaw occurs, start over. I usually do this exercise in climb beginning with the second lesson for 2 to 4 minutes at a time. In five lessons a student suddenly has it fall into place. Just like roller skating. A pilot usually takes only two sessions. Being done in a climb forces the student to apply the right rudder far differently than the left.
Duncan from the Netherlands
Interesting you should ask about the Dutch roll being from the Netherlands. If you go to my History pages you will find that Dutch roll derived from the old Dutch sailing ships that were relatively top heavy and would rock side to side while remaining on a straight course.
The purpose of learning to do the Dutch roll as a pilot is to determine how to apply rudder required to keep the nose straight. The crosswind limitation regardless of situation and method is to have no side load on the downwind tire when it touches.
You are most likely to use and teach the method you were first taught be it wing low or crab. The wing low (half-Dutch roll) tends to be uncomfortable to passengers. They need to be warned about what is being done and why.
The crab method is somewhat easier until just prior to touchdown. Well done it is a joy to watch, poorly done it is most damaging to an aircraft. I believe you should do both methods enough to retain proficiency in each. If you get into teaching, teach both.
I'm sorry to hear you mention that slips with flaps should make a difference in your landing procedure. Cessna created a problem where there was no problem. Yes, certain conditions on certain models can cause a slip to cause the nose to 'bobble'. Lowering the nose instantly stops it. Any slip is self correcting since the high wing will always stall first in a slip and go through level and un-stall. Suggest you climb to altitude and enter a variety of slips, flaps, stall sequences and see if you can make something unexpected happen.
Everything you need to do in a crosswind is in your imagination. The use of rudders in a crosswind just involves doing what it takes. You make the airplane do what it is supposed to do. What you experience is more what you think has happened and what actually did happen. Imagine what is supposed to happen and then make it happen.
As a student working on crosswind landings, or any landings for that matter, you must be asking yourself an infinite variety of questions about the process. High, low; close, far; fast, slow; up, down, in, out; it doesn't matter you must never focus on one item, the whole process must be put together to make the landing. As in a poker game, each landing is a new hand that must be bet and played with the cards you are given
The necessity for a stabilized approach even applies to crosswind landings. You should hold the crossed controls throughout the final approach. The crabbing approach, which requires a sudden application of rudder and aileron during the flare, seems to pose an unnecessary risk at touchdown.
The problem of crosswind instruction is not with students; it is with instructors. All to often I take my students up in a moderate 15-knot 60- degree crosswind for an hour. We are lonely. The FBOs with their cadre of young instructors have flight restrictions to protect their equipment. How is a student to learn to cope with the adversity of a crosswind if the opportunity of exposure is denied? A crosswind is a learning opportunity. An event to be challenged, studied, and conquered. If the student should discover that he is incapable of handling a specific wind, then that, too, is a valuable lesson. We must learn our limits, how better to learn them under experienced instruction?
I have had occasion, of late, to fly with several mid-time pilots who show weaknesses while making crosswind landings. On each occasion, my first query is as to whether or not they have been taught Dutch rolls. They may have heard of the Dutch roll or may even be able to describe it. None of these pilots admit having had instruction, proficiency, or awareness of the Dutch roll relationship to cross wind landings. Proficiency in the Dutch roll takes the mystery out of how much rudder and aileron to apply for a crosswind landing. Become sensitive to signs that will give wind direction and velocity. Check the windsock on final.
There are two distinct cross wind landing patterns for a given wind. Left or right patterns in less than 90 degree crosswind affects the amount of turn required to hold runway heading on takeoff, the turn and heading to maintain crosswind track, as well as the amount of turn required for downwind and base legs. The pilot must learn to take into consideration the velocity of the crosswind as it influences the ground track of the traffic pattern. The 90-degree crosswind does not affect track on crosswind or base except in terms of speed.
In a crosswind landing this runway alignment is doubly important. Each turn from base to final, left or right will require a completely different rudder/wing low technique in a crosswind. This can best be practiced where parallel runways exist or where left/right patterns can be flown to the same runway. When practicing crosswind landings it is very important that both left and right patterns be flown to teach planning of the crosswind, downwind, and base legs as well as turning to final with the proper wing low/rudder position. The initial practice of runway alignment can be done in calm to slight crosswind conditions. Later practice should be done in increasingly strong crosswinds even to the point of requesting a crosswind runway not currently in use.
Aircraft that are certified under FAR Part 23.233 requires the aircraft to be safe for operations in 90-degree winds up to 0.2 Vso. Vso is the slowest speed an aircraft is controllable in landing configuration, at approach speed, no brakes and no special pilot skills. For a 60-knot speed with the C-150 this equates at 12 kts. These are minimums. This means that anything beyond a 12-kt. 90-degree crosswind exceeds the design expectations for an average pilot. If during the certification trials of a given aircraft, only ten-knot winds were available then that is the limit of the demonstrated crosswind component. This does not appear to be a very realistic criteria.
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.
The rate of (aileron) reduction depends on the absolute magnitude of the crossword component and the developing forward speed.
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.
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.
Crosswind Proficiency (Instructor)
Once a student has mastered the basic full flap landing and go-around it is time to introduce the variations that will be required for crosswind conditions. The landings will be introduced when there is no crosswind and may be in only one turn direction. The first landing is a no-flap power on, the second a no-flap power off with a slip as required. Yes, slips with flaps. The next three will be with 10, 20 and 40 degrees of flap. The idea is to develop a student's perception of how 'high' or 'low' on approach is related to the aircraft configuration. 60-knot airspeed is used on all approaches. Each change in configuration requires a slightly differing round out and flare technique.
A good crosswind flight depends on getting the desired crosswind at a velocity up to 18 knots. The same series of landings are discussed on the ground by walking the headings. The variations of pattern size required by the configurations, even though 60 knots is flown throughout, is a major student learning experience. The different configurations are flown. Instructor demonstrations may be required to give the student a 'break'. This lesson should remove wind limitations from the student logbook. A later short session should include even stronger winds.
The maximum crosswind capability for an airplane depends on the capability of the pilot. The POH crosswind given as "demonstrated" is in no way related to what can be done with the airplane.
When a pilot has applied full rudder. accepted a somewhat diagonal into the wind runway alignment, increased both power and airspeed and still cannot keep the nose aligned with the diagonal centerline it is time for a go-around. I have yet to have an airplane being held straight with the rudder to scrape a wing tip. some say it is possible but I have yet to meet such a wind.
The most likely problem making a crosswind landing is when the winds are light and variable. A steady wind is relatively easy to set up. The variable wind keeps changing. When you have a light constant velocity crosswind you can set your correction all the way down final. You don't become aware of a variable wind immediately. After several changes in rudder and wing, you begin to appreciate acquired skills in Dutch roll. Into the flare your control applications become critical. Get it right or you will side-load the landing gear. together REAL fast, that initial swerve will turn into an pilot induced lateral oscillation that promptly ends in a ground loop or an "off runway" excursion!
Winds normally decrease with decrease in altitude but in the flare at low airspeeds you may need far more control input than you think. Do what ever it takes. This is not because of the crosswind but because of the decrease in airspeed.
At some point in my instructional program I take advantage of the strongest winds above 20 knots to practice crosswind landings. This is best done at a controlled airport so we can fly both left and right patterns.
I have even done it at non-towered airports with the cooperation of other aircraft. Even flying the pattern with a wind right down the runway requires considerable wind adjustments to make the pattern fit the situation.
The pilot must have the patience to recognize that he is not really making the touchdown decision as is the aircraft. Don't be in a hurry to get on the ground. The basic idea is to help my student to come up with his own personal limits. In my opinion it is the post landing yoke skills that are the frosting on the cake.
With a Crab and a Kick (Instructor)
There are two different ways to do crosswind landings, the slip and the crab. Both can be successful. The crab requires greater precision, experience, and luck. The crab is a "more comfortable" approach. The runway comes from the side and does not give the over-the-nose perspective of most approaches. You will be able to crab down to the runway in much more wind than you have control power to slip-kick-land in. An incorrectly timed kick to straighten the nose or a gust can excessively stress the side load capabilities of the landing gear box. (The mounting brace in the fuselage.) The experience required for such timing may be acquired too slowly or too late for really strong wind conditions. The crab does not handle gusty conditions well. The go around should be initiated before the slip-kick else the rapid application of power may cause loss of directional control.
Instructors planning to teach the crab and kick to slip method may wish to prepare the student by practicing the slip/opposite rudder configuration on long final approaches. The slip technique is relatively difficult to learn to the point of mastery. This additional practice along with Dutch rolls done on climb out provides additional exposure.
I do not teach the 'crab' method of crosswind landings because I feel the method offers too much potential for aircraft damage. Landing from a side slipping approach does not require such precise judgment and timing. In a crosswind use a power-on approach and flaps according to wind angle and velocity. Use additional airspeed only if needed to increase rudder power. The 1/2 Dutchroll method keeps both the aircraft path and nose aligned with the runway. The upwind wing is lowered to intercept and maintain the runway path and rudder aligns the nose. This method will correct for any wind velocity or angle up to the control limit of the rudder. On ground contact the lowered wing and aileron position protects against gust effects and the ailerons are correctly positioned for taxi. Full aileron should be applied in the landing roll even after the downwind wheel makes ground contact.
While there are still advocates (surviving) of the crab and kick method, the tri-cycle gear aircraft lends itself to the wing low opposite rudder slip technique. This method allows the pilot to determine and adjust to the crosswind during descent. Constant adjustment, similar to those used for a Dutch roll, must be made to maintain heading and alignment with the runway. The wind is changing constantly both as to direction and velocity during descent so the timing of the kick must be just right.
Landing in Turbulence
Don't use flaps. This will keep the nose higher and closer to the proper landing attitude. Touchdown speed may tend higher as the wind angle approaches 90-degrees. This should be recognized and avoided since a 90- degree crosswind makes airspeed the same as ground speed. Any increase in ground contact speed will multiply any side load effects. Failure to correct for a crosswind will cause damaging side loads and directional control problems.
The potential side loads of a crosswind increases as the square of the velocity. Even at low wind speeds the effects can be dramatic. 2 kt. wind 2x2 = factor of 4 side load; 3 kt. wind 3x3 = factor of 9 side load; 4 kt wind 4x4 = factor of 16 side load. Double the number gives quadruple the side load.
Keep power on during the approach and add one-half of the gust-factor to your approach speed. Do not seek a full stall landing. Fly the aircraft on to the runway, pull the power off and don't get any more weight on the nosewheel than may be required for steering. Remove any flaps. Permitting weight to be applied to the nosewheel will transfer weight from the main landing gear. Too much of such a transfer will cause the main wheels to lift off and lose traction. You are now steering a wheelbarrow with the rudder. Your safest option is to go-around. Salvaging a wheel barrowing landing is not for the faint of heart.
Unusual Wind Landings
Last week, as I walked up to the plane, I momentarily stopped and felt the wind. It was very light but could be perceived as a tail wind for the noise abatement runway currently in use. I had my student, sitting in the plane, get out and asked him to feel the wind. What followed was an analysis of what happens when a wind is classified as "calm". Even more importantly, we covered all the effects for the even greater probability that the wind would be "light and variable". We did some watching of aircraft making their landings. Landings were consistently long on the 5000' runway. Also, the landings were usually off to the side of the centerline.
On average, landings are made into runways with the twelve-knot relatively constant velocity and direction winds. Most of our practice and landings are into such winds plus or minus a knot or two. This experience has taught us to make the adjustments to the pattern and aircraft configuration required producing a satisfactory landing. "Calm winds" do not provide the clues the inexperienced pilot has come to expect. The light tail wind will increase the ground speed and shallow the approach angle. The usual changes in flaps, power, and airspeed fail to produce the desired results. This is caused by the fact that, while the tail wind may exist from 600 feet down to 100 feet the winds higher and lower will be from different directions and velocities. Even the tail wind will vary in velocity on final. The momentary truly calm wind compounds the difficulties.
The solution I offered my student was to extend the down wind leg of the pattern by twenty to thirty seconds any time the ATIS, wind sock, or AWOS indicates a calm wind condition. This adjustment allowed for the more shallow approach angle caused by the increased ground speed. The student was on a good approach but a new "calm wind" problem arose. In the flare the aircraft would begin a barely perceptible drift off the center line.
It seems that the intensity of the landing itself often so focuses the attention of the student that he/she is completely unaware of drift unless it is either pronounced or occurring just before touchdown. The likelihood or probability of this condition occurring must be pre-registered into the mind of the pilot any time the "calm" condition exists. With the runway out of sight in a proper flare the pilot must get his clues from the peripheral vision and the horizon. This takes both practice and experience especially in calm conditions. A failure to correct even the slightest side load on the landing gear is potentially very harmful to the aircraft since this is the weakest area of landing gear geometry. The instructor who does not foresee this area of landing difficulty is not properly anticipating an area of difficulty.
A few day prior to this flight another student and I had winds at 23 knots with higher gusts 40 degrees off the runway heading. Once again I proceeded to talk and walk through the headings for both left and right traffic that would produce an appropriate pattern. Just to get into the plane and start doing landings in these conditions would have been most inappropriate. We were transitioning the student from a C-150 to a C-172. This was his third C-172 flight but his first since getting his license.
In the pattern walk through, I gave the student the needed opportunity to see that some operational adjustments would be required. The initial takeoff would cause us to gain altitude over less distance so that our crosswind would need to be flown angled well into the wind and extended somewhat to create a wider downwind. The turn downwind would need to be angled away from the runway since it was necessary to fly a somewhat wider downwind leg both because of being in right traffic and because the wind direction would produce a an effectively shorter base leg due to a higher ground speed. The power reduction would begin before the numbers and even more angle into the wind would be taken to counter the increased wind effect at a slower airspeed. The wider downwind would give us a base leg sufficiently long to allow adjustments in the length and height of our final approach. The instructional emphasis here is that the pilot's control over the final approach must begin on the downwind leg if not sooner.
Under these or similar conditions the landing must be considered an option not a necessity. The go-around is the first choice option if the stabilized final approach cannot be established.
Flying the same runway in left hand traffic in the same wind conditions requires the pilot to make a shorter crosswind to help counter the wind's efforts to drift the aircraft away from the runway. The downwind leg must be angled toward the runway. The base leg again must be sufficient to allow adjustments to the height and length of the final approach course.
The instructional process for landings is not complete unless it exposes the student to the wind conditions described above. The opportunity to fly both left and right patterns in the same crosswind conditions is essential. Variety of pattern and conditions can be created by going to controlled airports with multiple runways. ATC will honor requests for crosswind runways and different patterns when traffic conditions allow. Changing the time of day is a good way to obtain varied wind velocity.
Training and recurrent training will not provide competence unless the pilot puts the training to work as a foundation for building experience. Training should not be confused with competence. Training is but a path for the pilot to follow to achieve competence. Do not believe that training will do the job for you that more flying will. Training does not lead to competence. Competence comes mostly from experience gained in flying.
Rules of Thumb for Landings
1. Downwind speed is at cruise in trainers otherwise at top of white arc
2. Reduce power abeam numbers
3. 1.3 of Vso on final.
4. 1/2 gust speed to Vso
5. Flaps to increase rate of descent requires trim change.
6. Reduce power after desired flaps to increase rate of descent.
7. Use 45-degree key position. (Conflict between official FAA and experts.)
9. Add power flattens slope; reduce power increases slope
10. A constant slope requires relative coordination of pitch and power.
11. The landing variables should be only wind and configuration.
12. Never fly below pre-selected airspeeds and altitudes.
13. Full flap landings are normal.
14. Don't add flaps below 200' AGL; Don't take off flaps on final.
15. Trim for every change of configuration and power.
Risks Related to Landings
1.Undershoots have more serious accidents than overshoots.
2. Full power is best undershoot option.
3. Frequent pilot problem is stretching glide without use of full power.
4. Aiming (judgment) ability is best from a steep approach
When Things Go Wrong
1. The go-around is the first and best option.
2. Trim for a constant airspeed.
3. Let the airplane land itself; don't force it.
4. Salvaging a landing is more luck than skill.
5. Excess airspeed creates problems
6. Directional control problems arise from premature touchdown.
7. Anticipation is an acquired skill honed by practice.
8. Slow down straight-ahead, not in a turn.
9. Practice yoke position skills in all winds.
--A wind blowing directly on your route between two points doubles the time effect as much as would a direct crosswind of the same velocity.
--Figuring the crosswind component:
Divide TAS/60 times angle of crab = crosswind component
Each degree of crab is one knot of crosswind for each 60 knots of airspeed
10 degrees of crab at TAS of 60 knots is a 10 knot crosswind
10 degrees of crab at TAS of 120 knots is a 20 knot crosswind
8 degrees of crab at 90 knots TAS is a l2 knot crosswind
12 degree crab at 480 knots = 96 knots.
--Flying on the downwind side of a valley allows you to use lifting effect of thermals to increase speed.
--A 10-knot wind rising on a 20-degree upslope gives 340-fpm lift.
Knowing this will help the C-172 pilot climb out of Reno or Tahoe. Making eights along the ridge
should include always making your turns into the wind and flying as close to the ridge as comfortable.
--When making turns about a point the steepest bank is required when in a tail wind. Groundspeed is higher.
--In a pattern about an airport the steepest turn is required when ground speed is highest.
--When a wind is at 45-degrees to all legs then, in order to maintain the same radius of turn, a steeper
turn is required where the larger heading change occurs. (Draw it out)
--If a headwind exceed your ground speed you cannot make progress.
--If a crosswind exceeds your true airspeed you cannot fly across it.
--Consider practicing taxiing on one wheel.
--Never attempt more than two unsuccessful crosswind approaches at a runway.
--Declare an emergency and use a taxiway that lets you with more favorable winds.
--The basic crosswind landing skill of doing the Dutch roll must be anticipatory and automatic.
--Following a straight line in a crosswind while flying low and slow is another skill that can help.
--Long straight-in landings are a good for sideslips to each side of runway awhile keeping nose straight.
Flying the pattern
--Get a 'wind update' on final by radio or windsock.
--Crosswind patterns are flown with crab until on final.
--Every pilot/aircraft mix has crosswind landing safety limits.
--Crosswinds vary not only in direction but also with altitude.
--If you can't make the approach look and feel right, go-around.
--Every landing pattern has a crosswind component somewhere.
--When crosswind blows you into the runway, fly wide to lengthen your base leg.
--If you are not prepared for the apparent speed and turn required on base, go-around.
--Always fly indicated airspeeds and anticipate illusions caused by wind velocity from the rear.
--All crosswind practice should be in a variety of pattern directions, wind velocities and angles.
--The controls required to get the upwind wing down on final are quite different if for right or left turn.
Final to Touchdown
--Winds usually decrease with decrease of altitude.
--The nose must be straight with the runway at touchdown, otherwise
--Increased approach speed is always an option to obtain greater rudder authority.
--The slip approach is better in that it allows the pilot to see how well he is aligned.
--The only option for not being aligned with the runway at touchdown is the go-around.
--The so-called 'demonstrated crosswind component' has nothing to do with actual limits.
--Cross wind accidents are derived from rusty skills, distraction and poor decision making.
--Pilot selection of flaps used in every landing should be based upon his personal skill limits.
--Pilots require more instruction in extreme wind conditions and recognition of their skill limits.
--The number one touchdown accident cause is not correcting for wind direction and/or velocity.
--The number two cause was instructor's failure to react appropriately and in time for the conditions.
--The use of flaps increases the difficulty of crosswind landing proportionate to wind velocity and angle.
--Constants of airspeed, power, flaps, and alignment are best assurance of a successful landing.
--Other than alignment, set your constants early and vary only one at a time to adjust descent path.
--The lower and slower you get into the flare the more critical your aileron and rudder adjustments.
--Most difficult skill is that of having the patience that allows the aircraft decide when to touch down.
--The vast majority of crosswind landings do not have the proper wind correction at touchdown. Lurch!!
--Be sure to advise your passengers that landing wing-low and on one wheel is the way it is supposed to be.
--Most difficult crosswind taxiing transition is when wind goes of headwind to tailwind.
-- Of the 1/3 share of all loss of control accidents that are landing accidents most occur in crosswinds.
--The airplane wills always weathervane into the wind while taxiing if uncontrolled by brake and rudder.
--Keep some power on to aid rudder authority after touchdown. Yoke goes full over and back into wind.
Dudley on Winds...
I think the somewhat predictable Texas winter winds have spoiled me early on the flight training phase. With summer approaching and variable southerly winds, landings should get more interesting, which is the problem.
I know how to do a crosswind landing, and have done several to near perfection. The problem arises when setting up on final just prior to touchdown. If I set up for a quartering easterly crosswind on final, next thing I know I get one from the west just before landing. Compounding the problem is not immediately recognizing the need to apply opposite trim to keep the plane straight a few feet from touchdown. I have very little width at 52F and winds are often times extremely shifty and turbulent due to the buildings on either side of the runway.
My CFI is very insistent on "flying the plane" regardless of the windsock indication. Back at the FBO today he offered the advice to "look around" at touchdown to improve peripheral vision and get a better awareness of the
plane's attitude against the centerline. Sounds like that makes sense. I've been focusing a few inches to the left of the spinner and have admittedly developed tunnel vision when landing. That has worked for flaring but apparently not for lateral landing adjustments.
What has worked for you all when shifting winds create landing alignment problems? Should I work on the peripheral vision or is there something else I should try?
Your CFI is right. You NEVER "set up" for anything and expect conditions to remain as what you have set up for when it comes to landing an airplane. Flying, by it's very nature, is done in a constantly changing dynamic, and you as a pilot, have to be ready to handle any and all changes the instant they occur. What this means is that rather than set up for an expected condition such as a left crosswind. You have to use any and all cues available to you. Do this by constantly assessing the wind situation and what it's doing to your airplane at any given moment in time during the approach.
If you see a sock that indicates a specific crosswind, by all means expect that, but don't just blindly accept that as a given! Nothing is a given in a changing dynamic....NOTHING!! You FLY the airplane based on what your cues are telling you and nothing else. Remember this if you remember nothing else. The airplane is constantly telling you what it wants you to do. WATCH the airplane.
As for catching any change as it happens; this shouldn't be hard at all. You're probably missing it due to over concentration on one area or one thing. Relax. The secret to picking up on what the airplane is doing is to
SCAN......not focus!!! Keep your eyes moving along the runway length as you descend through final. Don't get hypnotized on any one object or item. Keep your scan active and your mind relaxed. When you get to the point where you can do this, you will pick up instantly what the airplane is telling you about drift. Make immediate and ONGOING corrections. Landing an airplane is a flowing continuous series of constant subtle and gentle correction applied with whatever control pressures are necessary to put the airplane where you want it to be in the sky. The airplane is the best teacher you will ever have as long as you fly as a pilot. Learn to recognize what it's telling you. All the best to you and the best of luck,
Thanks for the responses. Sounds like I need to get more in touch with the
plane, which will come with time and experience (presently have 21 hrs and 100
t/l). Given the time so far, should I already have developed that skill?
Not necessarily. It comes in time and everybody finds it in their/its own way. The important thing is to realize that it's there if you look for it, and then to start looking and find it as soon as possible. You'll know when you
have it. From what you are writing, I'm fairly convinced that if I were teaching you, I'd have you pay special attention to relaxing a bit more and developing that scanning of the runway ahead I was talking about. It's
important that you realize that on especially on final, you don't want to ever find yourself focused heavily on any one thing. Start practicing picking up things on the fly (no pun intended).
Consider your central area of constant interest the runway ahead of you as that relates to where you are and where you want the airplane to be. Everything else......control pressures.......instrument readings.......flap
positions......everything....is simply being noted and used to get you to where you want to be in space in relation to that picture. For example, learn to work ahead of yourself on final. Take an airspeed visual check for instance. Don't look at the ASI and stay focused there as you correct an airspeed error. That takes your attention
away from the airplane and puts it on the ASI which is secondary data....necessary data...but secondary to flying the airplane. What you need to learn to do is look at the ASI, note the airspeed......say it's a bit low......now look at the runway which is your main scan area and make a slight pitch correction for the airspeed.......now check the ASI again.......back to the runway.....make whatever correction is needed again.
What you are developing is the ability to do one thing while focused on another, which is basically what flying is all about. In effect, by doing things this way, you are always in front of the airplane, which is exactly where you want to be. The main focus of your attention is always the runway and your relationship to it. Even as you are making a drift correction, you are checking something else in your peripherals. It's a constant flowing
thing that doesn't end until the airplane's stopped on the ground.What I've told you here is the complicated part :-)
The best part is that the way to put it all together is through practice. Each time you do it, a little more of the puzzle will slide into place for you. You might not even realize how well you're doing. Things will just begin to get easier for you. It's a natural process that everybody has to go through so don't worry; it'll come!
Your question, and the fact that you knew to ask it, is a sure indicator that you're on the right path and will have this down pat fairly soon .
Thanks again for your time in responding. Relaxing is another issue I have
coming into 52F after TnGs at nearby strips that seem four times as wide. It's
sometimes a "white knuckle landing" if gusts/wind shifts are
prevalent. One thing I've done to be more responsive on the rudders is to lift
the heels slightly on short final. Not sure if that's proper technique but it
forces me to focus on the rudders more than I would otherwise.
Iíll ask my CFI for critique when things go wrong and ask for corrective advice. He has done so, but this issue seems to be more problematic than most.
I would suggest you do the exact opposite of this. What you want on the rudder is the ability to make extremely subtle and gentle corrections with or against aileron as the case may be on final. The best way to accomplish
this is to get in the habit early on of keeping your heels on the floor unless you're on the brakes, and even then, you only should be lifting that heel just enough to get the brake you need.
No....don't raise the heels off the floorboards to focus on the rudder.
Keep your heels down on the floor and use your ankles as a pivot for your
upper foot to use to apply the pressure you need; which ideally should be a
venire setup. With your heel free of the floor, the force input for the rudder
application comes from the knee which is way too long an arm (no pun intended
:-) to get the extreme subtle pressures you need for proper rudder use.
If you were flying with me, I'd classify this as an error that needed correction immediately! Try it and see if it's better for you. If you're lifting those heels, that might very well be a source of one of the problems you're having. FWIW, even flying extreme aerobatics in a Pitts, I NEVER take my heels off the floor and raise them high enough that I'm not using my ankles as a fulcrum for my foot on a rudder pedal.
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Related Reading 4.34 Thoughts on Landings
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