In flight school we may get the idea that we turn by application of coordinated aileron to bank with ruder to control adverse yaw followed by pulling back on the elevator to actually turn. While aerodynamically correct, there are some problems actually doing it this way. First, the nose goes the wrong way initially unless we lead rudder. Second, pulling back on the elevator is what causes the airplane to stall.

Last Wednesday I was working wind of 30 gusting to 40 with one of the local instructors, Shim. We were using 40 degrees flaps, the apparent brisk walk rate of closure approach, and side slip into occasionally right crosswind. The wind was S and occasionally SSW and we were landing 18. Trees lined the runway 200' west and 200' east of the runway with an east-west road across short final. Pretty squirrelly.

On one approach, coming into ground effect with groundspeed down to about 20, we were inadvertently banked 30 degrees left. My right leg is my bad leg, but I put the right rudder to the floor ahead of Shim. The wing incidence of the banked wing will cause 1 g turn without pulling back on the elevator. Because Shim was making a power pitch approach, he had some back pressure on the elevator. So turning left was turning the nose left of the centerline. Right aileron with coordinated rudder would have eventually stopped the left turn by bringing the left wing back up...long after the crash. Only immediate right rudder to the stop was quick enough to prevent turning into the ground. The immediate effect of the down aileron was pulling the left wing further back. As I pointed out to Shim, we had a longitudinal alignment problem. Early rudder correction, or even better dynamic proactive longitudinal axis stabilization, of that problem keeps the wing level or in a stabilized bank into any crosswind.

In somewhat calm or steady wind, dynamic proactive rudder to bracket the centerline will keep the wing level. In rough air, reactive full rudder may be needed to level the wing and maintain longitudinal alignment. If we had been very actively dynamically and proactively walking the rudder to nail the centerline, we likely would not have been severely banked left by gust spread. It was a good lesson where Shim learned what coordinated aileron and rudder was not able to do and even better what right rudder to the stop was able to do. We touched down slowly and softly on the left edge of the runway with the nose and our butts going down the left edge of the runway. The wind could drift us left quicker than we could change bank to correct, but could not change our longitudinal axis so long as we dynamically and proactively maintained longitudinal axis.

Finally, we accomplished our original goal of getting Shim familiar with aggressive throttle movement to control the glide angle disruption of gust spread and terrain/obstruction interference with stable relative wind.

Before the flight I told Shim I had known Justin, the FBO, a long time and if anything happened we would be at a very slow groundspeed.

If we were teaching slow flight at just above stall airspeed or takeoff and departure stalls, we would be teaching use of rudder only for anti-turn anti-stall anti-spin control. Same with the falling leaf.

I understand that we are at 1.3 Vso at the round out and that aileron is still effective at that airspeed. With the deceleration on short final caused by not allowing the apparent brisk walk rate of closure to increase to faster then what appears to be a brisk walk, we are near Vso and continuing deceleration to the airspeed of stall in low ground effect upon touchdown slowly and softly on the numbers. Using this technique, we should certainly be levelling the wing with rudder only. We should actually be keeping the centerline (white striped line) or apparent centerline( (angle into the crosswind) strictly between our toes using dynamic proactive rudder movement, which automatically levels the wing (no crosswind) or stabilizes the bank into the crosswind.

Finally, if we are using the round out and hold off technique, we will encounter this aileron becoming ineffective and rudder only being required to level the wing as we are finally descending to the surface well down the runway.

Regardless of technique, rudder only is the anti-turn control on short final until the airplane is tied down. Longitudinal axis alignment, at any airspeed, is a rudder only technique. Using coordinated turns for longitudinal axis alignment is an ineffective, wing wobbling, technique that is dangerously ineffective, especially in strong gust spread. Using aileron does not aid the rudder in directing our course but only introduces adverse yaw. Adverse yaw is detrimental to either reactive rudder application to yaw back to the centerline or certainly to dynamic proactive rudder application to bracket the centerline.

Jim wrote — On one approach, coming into ground effect with groundspeed down to about 20, we were inadvertently banked 30 degrees left. —

My question is how the wing drop was best first sensed? I doubt that it was from looking at the wing. But rather being (more) sensitive to the movement/alignment of what was straight ahead (and it probably wasn’t the far end of the runway after the wing dropped occurred.)

When I do an ABWROC approach, I line up by sighting as far as I can down the runway. Becomes easier and more precise with lowering altitude. Then I pick my ABWROC Target; usually the numbers ( or one of them). I go back and forth quickly between the two views — staying in each only long enough to establish that am longitudinally straight, and not speeding up. Usually I have to change my ABWROC Target as I close in on it and now pick a convenient runway centerline segment. Once down in the landing zone (foot or less off ground), I look down that runway as far as I can see and only peripherally at the sides of the runway. All the while pulling the yoke into my stomach.

My bet is that Jim sensed the angular rate of the straight ahead vector. If you are looking far away, even small rate changes are noticeable. The wing drop probably resulted in a very noticeable slew rate.

One of the E3 exercises is off centerline landings —- on the runway left or fight of centerline. Not real clear on the extent of reasoning if not only to show students that landing on the center line is not sacred? But maybe there is more? Say in the case of the Malibu crash, the pilot is clearly cognitively challenged (just before the crash) and focuses on something familiar — the numbers or centerline marking. This is a kind of a trap that could be avoided by focusing on the larger situation which is probably not helped by at all by man-made markings on the runway.

Am going to experiment with off centerline landings when I get my plane back to WY at my practice base KAFO, home of the Husky. Nice flat lands on 3 sides whereas at 46U, one can easily become a swimmer in the Palisades reservoir.

And this begs the bigger question. If you don’t need the runway centerline to keep lined up, why not land on the R side of the runway in a strong L crosswind and vice-versa? More leeway, if drift does occur, in spite of best efforts. In the backcountry there is often just the runway —- only just wide enough and no centerline marks. But you do what you have to for a safe landing or go somewhere else.

Sorry, now I’m rambling like Jim. But you gotta to evaluate new trains of thought!

Blue skies,

Tommy

Did I read correctly that you're using 40* flaps in 30G40 conditions?

Tommy,

All of your thinking sounds fine. Last Wednesday we were moved sideways when we crossed the east west road on short final by greater crosswind at that point with gust probably causing the left bank as well. I did not become alarmed with being moved sideways. It was, as you said, the nose coming off longitudinal alignment to the left. I delayed because Shim was getting better with rudder only and some dynamic proactive rudder movement to correct that. When the left wing suddenly went down as well, I reacted immediately with full right rudder. Shim was just a bit unglued and in post flight I learned that he was unsure about such extreme control in such extreme conditions. The solution is to get much more demanding with dynamic proactive rudder movement to nail the centerline, or optical adjusted centerline in the angle across the runway. Our wind that day was mostly right down the runway with just the venturi made by the east west road moving us sideways at that point. When we have some more iterations of dynamic proactive rudder movement and if we have lapsed on that, reactive rudder to get the nose going the same direction as our butts rather than trying to return to the centerline with a coordinated turn in that direction.

The effect of any coordinated turns on short final in these extreme conditions is immediate loss of longitudinal axis control.

Happy flying,

Jim

CParker,

Yes, you read correctly. I use full flaps for all landings with all airplanes I have flown, most US trainer 65-250 hp size. They are very effective at 40 degrees with Cessnas. The wing, while very large, has less high lift camber. 40 degree flaps allow it to be flown at reasonable pitch attitude in power pitch approach to the ground (short field.) The big flaps work equally well in strong winds and gust spread. With gust spread, we have to use the throttle as a rate of descent control all the way down to touchdown. In a gust caused balloon, we may have to close the throttle and then adjust. In a gust caused sink or mush, full power and then adjustment may be required.

Decreasing flaps and increasing airspeed such that groundspeed is actually higher than in no wind conditions is all too common a reaction to gust spread. Lots of airplane damage results for LOC problems at high airspeed. The airplane will not really land at high airspeed and it certainly is not designed to roll around on the ground in gusty air at high airspeed. Any loss of longitudinal alignment on the ground at high speed is hard on the gear and usually begins LOC damage.

Had I not applied full right rudder to get the nose going the same direction as our butts, we would have touched down in a bank at about 20 knots groundspeed. Not good, but not as damaging as doing the same at 69 knots groundspeed.

The solution is neither 40, 30, 20, 10, nor zero flaps. The solution is to keep the nose (between our toes) going exactly in the same direction as our butts (longitudinal alignment) on touchdown. Next, we can choose whether we want the throttle actively controlling glide angle and rate of descent on touchdown. Round out and hold off gives up throttle, the best glide angle and rate of descent control. The apparent brisk walk rate of closure approach, or any power pitch approach, allows use of throttle as the glide angle and rate of descent control all the way to touchdown.

At fast approach airspeed, the ailerons are effect until the end of the hold off and the wing no longer has enough relative wind to overcome lift. Any power pitch approach, however, allows the use of throttle much longer keeping the rudder effective for both longitudinal axis control and when we keep the nose going the way our butt is going, the wing is automatically leveled or stabilized in bank into a crosswind. Slow airspeed on short final absolutely requires rudder application, lot in gust spread, to both maintain longitudinal alignment and keeping the wing level (anti-turn.)

It is not harder to do it with full flaps and deceleration on short final, just different. Actually, it is easier in most conditions and very, very slow and safe. In strong headwind component without gust spread, it is like having time to sort thing out and even correct mistakes in plenty of time. In gusty conditions it is a lot of serious throttle and rudder control work, again with lots of time to sort things out.

Jim

Fascinating, thanks for the insight.

OK, I'll bite. What the heck is an "ABWROC" approach? (Google doesn't seem to know either...)

Apparent Brisk Walk Rate of Closure Approach. Tommy came up with the acronym.

JP256,

You younger Army Aviators, you and CamTom12, were less indoctrinated I think, but The Apparent Brisk Walk Rate of Closure Approach is an Army term and helicopter technique.

Jim

Just to emphasize the difference, harm, drives me crazy, difference in coordinated turns or rudder only on short final, any use of aileron other than to set a wing into a crosswind would be anti-longitudinal axis alignment. Crab to short final you say. Sure, that would be dynamic proactive rudder only to direct our butt down the centerline extended and thereby automatically keep the wings level.

The law of primacy gets in the way of learning dynamic proactive rudder movement to bracket the centerline extended with pilots who have learned in tricycle gear airplanes, especially with those pilots who have thousands of iterations of successfully reacting to longitudinal axis misalignment by turning to fly back to the centerline extended without actually realigning the longitudinal axis with rudder only. Touching down slightly misaligned or even in a slight turn is not as 100% upsetting as with tailwheel airplanes. I know tailwheel Brian teaches it in his 120, but he is a show pilot and it is an impossible turn technique that deals with not getting lined up with the runway. The anti-turn control, especially dynamic proactive anti-turn control, is not emphasized in nosewheel airplanes.

And without the fear of touching down with the nose going at a slightly different heading than our butts, even good tailwheel sticks may not realize how much more effective rudder only anti-turn control is against wing level upsetting turbulence at altitude. Anywhere in the physical atmosphere (on the runway, on short final, or at altitude) dynamic proactive rudder only movement will prevent longitudinal axis misalignment. Preventing longitudinal axis misalignment keeps the wing level much more effectively than reactive or even dynamic proactive coordinated turns. By leading rudder in precision Dutch rolls, we could make so called coordinated turns maintain longitudinal axis alignment, but nobody seriously wants to do that. Yet only that would make coordinated turns or aileron reaction to gust spread upset effective.

Instructors and teachers, dynamic proactive muscle memory training starts with the beginning of taxi and ends with the airplane being tied down. With nosewheel airplanes, taking the slack out of the nose wheel and rudder control with dynamic proactive rudder movement is necessary. And keeping the nosewheel or tailwheel exactly on the yellow line (optically between both student and instructor's toes) is necessary. We just aren't going to use the technique when we need it unless it becomes an unconscious thing. Yes, the DPE will ask if you are a tailwheel pilot. Tail wag away. Don't wing wag. Adverse yaw is not our friend. Anti-turn dynamic proactive rudder only yaw is effective to keep longitudinal axis alignment (or butt alignment in a crab) which is effective in keeping the wings level.

A major problem with anti-turn control is that many pilots learn early in flight school to coordinate aileron and rudder (not lead rudder) to keep the wings level and hold a heading +or-5 degrees. First, five degrees of heading change is plenty to un-level the wing. A great deal of wing wagging occurs with this method of anti-turn control, especially if the nose goes the wrong way initially unless we lead rudder. Wing levelers work fine for IFR work, but you can't stay in a crop row with them. OK, we don't need to stay in a crop row. But we do desire that the wing stay level, even in gusty conditions.

After thousands of iterations of wing wagging to maintain heading, it is hard to destroy this concept in order to create dynamic proactive rudder technique to keep a distant target between our toes. +or- 5 degrees is way, way to sloppy. While dynamic proactive rudder to keep the pipper on the target horizontally keeps the wing level in cruise for comfort, the technique does much greater service on short final to both keep the centerline extended and to keep the wing level or stable in bank into a crosswind.

The anti-turn control is the rudder. Actually dynamic proactive rudder to be precise at keeping the target stable between our toes or keeping an exact wings level crab angle that will direct our butt precisely to the target. Either dynamic proactive rudder action will also keep the wing level or at a stabilized bank into a crosswind with the side slip.

Because it is so much easier to teach this technique on short final or just to direct our nose precisely to a target with the hands in lap, I have favored no hands on the yoke and taught it that way. This, I fear, is disturbing to pilots who have constant aileron usage muscle memory. I have teased about doing Dutch rolls on final, but now I have come to the realization that might be the way to get around that problem. Let's look at dynamic proactive rudder only usage as Dutch rolls to a maximum of one degree bank (no roll). I think any who have done them will admit that rudder must be lead in Dutch rolls to maintain the target between our toes. Otherwise adverse yaw will sling the nose the wrong way every time. So hang on to that beloved yoke and do no bank Dutch rolls with the rudder. Now you have dynamic proactive rudder. No sweat GI.