Crosswind landing debate • Redux (Go the crabs)

[Garfly]

Crosswind operations—no drama, please

 

https://airfactsjournal.com/2021/09/crosswind-operations-no-drama-please/

[kgwilson]

Good article. When I was training crabbiing and rudder to straighten just prior to touchdown was taught. Wing down approach/sideslip was not.

 

In very windy cross conditions I now do use a bit of wing down when close to the ground but approach to just a few feet off the deck is always a crab. When landing in over demonstrated crosswind limits, the problem is not landing but keeping the aircraft straight once on the ground. As I lose forward momentum the aircraft wants to weathercock and controls become useless. In this situation I always choose the grass (if there is any) as it allows the wheels to slip sideways a bit without digging in. I get a bit of a shudder as the plane skids and skips till slow enough for its weight to keep it fairly straight. I have a castoring nosewheel which helps in when going fast but makes slow crosswind taxiing a bit more challenging.

[RossK]

Crab techique for me.

I agree with the article on the point of doing what you always do. Crab techniue uses all the same speeds, decent, etc, that you use every other landing, just not pointing the nose down the centre.

Also, instructions for our AC says crab is better as with a pretty low wing, it's very easy to touch the wingtip on the ground using the wing down method.

I also like the point made in the comments about picking x-wind right to left over left to right if you can for take off.

I have had the experience of running out of right rudder on a left to right x-wind takeoff. The nose weathercocked left as soon as the nose wheel was off the ground, despite full right rudder. 

[Flightrite]

When you drive a plane with under slung pod mounted donks you crab, I keep the same principle in basic stuff.

[facthunter]

it's easy to bang an engine or flap on the runway with a heavy and I'm not sure the feeling of leaning would impress the Pax either all down the approach. The velocity and mass of a heavy keeps it going the same direction for a sufficient time when you kick it straight for it all to work out ok if you don't allow the upwind  wing to rise at any stage. The act of straightening the plane gives the upwind wing a tendency to rise more which mucks it up' if you don't counteract it.

  Smaller stuff be slipping into wind and land on   the into wind wheel Just how much bank you can put on depends on the planes wing position and dihedral. AND how effective the rudder is. High wing can be a more extreme  looking arrival if you have to land in a very strong wind . Of course once on the ground you have to keep it on the runway as you reduce speed.. It will want to weathercock into wind.  and you have to keep a lot of aileron on to stop the wing lifting. Nev

[RFguy]

My Xwind landing are all sideslip/wing down/wheel down.... (high wing) . I learned that way, the Brumby had a very effective rudder, espesh with a bit of power on as you do .... Never attempted a short field in max X wind, I tend to chew up runway getting the wing /wheel down. Maybe the crab might be better for the short fielder at max Xwind... dunno. 

[cscotthendry]

I use the wing down method. Because? If you crab in, eventually you have to transition to the wing down (crossed control settings) to straighten up to the runway. If you start with wing down (crossed controls) you fly that all the way to the ground, no need to change methods just as you're about to touch down. Also it presents the pilot (me) with a direct view down the runway on final which I find easier for lining up the centreline rather than an oblique view through the side of the windscreen.

HOWEVER, I'm aware that wing down has its limits for low wing aircraft.

[Bosi72]

Good article but many comments 

are better than the article.

 

My instructors taught me not to fight the wind all way on final, nor during climb immediately after liftoff. Wings level and crab into the wind.

 

However everyone touches ground with wing down, since damage may occur if land crabed. The question is when to do transition from crab to wing down. Transition just before threshold works for me.

 

Also it is better to takeoff/land when the wind is coming from the right (clockwise props) due to all tendencies pushing nose to the left (p factor, slipstream, torque).

[APenNameAndThatA]

The author’s arguments against wing-down landings were 1) crossed controlled is not how you normally fly, 2) the aiming point changes, 3) descent rate changes and 4) that’s not how aces/full-time/pros/airline-pilots/he does it. Those are the worst arguments ever. What a toss pot, referring to himself as an ace.🙄

 

The author neglected to mention that airliners cant land in a sideslip, so airline pilots don’t have to worry which method is best. 

 

The author also ignored that airliners have a larger mass to surface area ratio and therefore will be blown sideways less than light aircraft. It’s not like they have to tie them down lest a gust blows them over. 

 

And that airliners dont get damaged if you land in a crab. 

 

The argument against crossed control flying is particularly bad, because crossed control flying is associated with danger. The exception is sideslipping, where crossed controlled flight is perfectly safe. In other words, crossed controlled flying while landing is safe. 

 

The article also didn’t bother attempting to answer the important questions: when do you straighten the nose? How do you stop yourself being blown sideways?

 

The problem with the Foxbat is that sideslipping, one can run out of rudder when the cross wind is not too strong. 

 

It doesn’t look like Air Facts is what it once was. Wasn’t it started by the guy who wrote Stick and Rudder? 

 

 

 

 

Edited September 17, 2021 by APenNameAndThatA

[kgwilson]

5 hours ago, cscotthendry said:

I use the wing down method. Because? If you crab in, eventually you have to transition to the wing down (crossed control settings) to straighten up to the runway. If you start with wing down (crossed controls) you fly that all the way to the ground, no need to change methods just as you're about to touch down. Also it presents the pilot (me) with a direct view down the runway on final which I find easier for lining up the centreline rather than an oblique view through the side of the windscreen.

HOWEVER, I'm aware that wing down has its limits for low wing aircraft.

I disagree. You do not eventually have to transition to wing down at all. For most crosswinds except approaching the aircrafts crosswind limitations (say 15-20 knots) the wings stay level and you just kick the rudder to straighten up to the runway a second or two before touchdown, and keep the rudder that way and ease off as you slow. You only use aileron in to wind after touchdown and ease that off as you slow. It is essentially a reverse of the method you use for takeoff. When climbing out in a crosswind if you want to keep along the centre line you will be in a crabbing upwind climb.

 

My aircraft is a low wing so will handle crosswinds better than a high wing IMO due to friction slowing the wind closer to the ground. I was trained in a C150 though and the crab/rudder flick was the only method taught then (1980s).

Edited September 18, 2021 by kgwilson

[onetrack]

I used to watch the Caribou pilots in Vietnam landing in a strong cross wind. They'd crab at an alarming angle until only a few feet before touchdown, then straighten up with a rudder kick and plonk down smoothly and very neatly, in line with the runway centreline. It was quite amazing to watch.

[facthunter]

 Yes but they'd have plenty of power on and have a whopping big rudder.

Very low wing loading planes are quickly blown away when the slipping stops. They all have a x wind limit and so does the pilot. If you plane is difficult to taxi in strong winds it will be difficult to land in them also.  Kicking a low inertia straight you have to get the wheel(s) on the ground quite quickly and in any sort of gusts that is virtually impossible to guarantee no matter how $#1t hot you are..

 IF you have a stol type land into wind. 

 Don't learn from a forum alone but you can get the essential problems in your mind. Nothing beats good instruction. Lets face it many will always be almost terrified of crosswinds and quite a lot of planes don't handle them well. Know your limit and the planes limit and don't exceed either. Spoilers help big stuff stay planted on the runway after touchdown and allow brakes to work particularly on  wet runways

   Quoted cross wind components MAY be what was available on the day at certification. Very good operators may be able to exceed them but they are REDUCED for water on the runway gusts and  visibility etc. Nev

Edited September 18, 2021 by facthunter

[skippydiesel]

I believe in flexibility - I use whichever method seems to give me the best result on the day (wind speed/direction). Usually crab on final, side slip over the fence, for a single wheel touch down - works for me. Way to high on final, slip for higher rate of decent, no airspeed increase. So my advice - practice both systems. 

[facthunter]

It doesn't have to be all one or the other, I agree. In my experience few do side slipping well and some planes don't sideslip well. If you have a plane with NO flaps you should learn how to sideslip it properly. Being a bit high and intentionally slipping some off is pretty normal. Nev

[cscotthendry]

5 hours ago, kgwilson said:

I disagree. You do not eventually have to transition to wing down at all. For most crosswinds except approaching the aircrafts crosswind limitations (say 15-20 knots) the wings stay level and you just kick the rudder to straighten up to the runway a second or two before touchdown, and keep the rudder that way and ease off as you slow. You only use aileron in to wind after touchdown and ease that off as you slow. It is essentially a reverse of the method you use for takeoff. When climbing out in a crosswind if you want to keep along the centre line you will be in a crabbing upwind climb.

 

My aircraft is a low wing so will handle crosswinds better than a high wing IMO due to friction slowing the wind closer to the ground. I was trained in a C150 though and the crab/rudder flick was the only method taught then (1980s).

If you're flying straight and level and you kick the rudder over, what happens to the wings?

I think your statement that the wings stay level is not accurate or true. It doesn't matter if you do that at 10,000 feet or 10 feet, the effect is the same. If you kick the rudder away from the wind, the other wing WILL rise. That is how modern airplanes are designed. Worse yet, it will be the upwind wing and if the wind is strong enough it will lift the wing even more. What you are unconsciously doing is crossing the controls at the last instant. If that works for you, that's good. There isn't a right/wrong answer to this, only a preference dependent on your training and the type of aircraft you fly.

Edited September 18, 2021 by cscotthendry

[Flightrite]

many 1000's of hours (some think I'm not a pilot, I love that😂) I've just crabbed & kicked it straight just prior to touchdown, heavy metal or toy planes:-) Like conventional U/C machines, some fear them & the boogey man that goes with them😂 99% of my Ldg's are on grass (if possible) regardless of the x-wind.

[facthunter]

Grass is class, especially if you have no brakes. Nev

[F10]

Crab for me…kick it straight on touchdown, stick over into wind. Wing down just complicates things, I’ve seen more getting out of shape lifting that low wing (aileron will be down, on the into wind wing….not great) than stick into wind on touchdown. But I concede, probably a personal preference. Crabs worked for 6500 hrs….not changing now. By the way, airliners gear is engineers with being able to touch down sideways, it’s actually recommended, changing a few tyres in that Bob Janes tyre shop hanging below them, costs a lot less than scraped engine pods and possibly fodded engines.

Edited September 30, 2021 by F10
Typo

[cscotthendry]

9 hours ago, F10 said:

Crab for me…kick it straight on touchdown, stick over into wind. Wing down just complicates things, I’ve seen more getting out of shape lifting that low wing (aileron will be down, on the into wind wing….not great) than stick into wind on touchdown. But I concede, probably a personal preference. Crabs worked for 6500 hrs….not changing now. By the way, airliners gear is engineers with being able to touch down sideways, it’s actually recommended, changing a few tyres in that Bob Janes tyre shop hanging below them, costs a lot less than scraped engine pods and possibly fodded engines.

One of the things I don't like about the “Crab and kick it straight” method is the precise timing that requires and the other thing is changing from the Crab to the Crossed controls at a very critical point of the landing, ie right at touchdown.
If you miss the timing of the switchover, you'll start to drift off the runway, or worse yet, if there's a bit of a bump on the runway (as most I've taken off and landed on have) and you snag a wheel while still crabbing, it can be unpleasant at the least or damage the plane at worst. But in any case, you are still landing with crossed controls.

BTW The aileron on the into wind wing is actually up, not down. If the aileron were down, it would lift the into wind wing.

Finally, this was not meant to sound snarky and I hope it doesn't. As I said before, cross wind landing technique is a personal choice and it comes down to what works best for each pulot and aircraft. There is no “right” answer.

[turboplanner]

8 minutes ago, cscotthendry said:

Finally, this was not meant to sound snarky and I hope it doesn't. As I said before, cross wind landing technique is a personal choice and it comes down to what works best for each pulot and aircraft. There is no “right” answer.

There are definitely situations where one method is more suitable than the other, but I think it relates more to the aircraft than the pilot.

The pilot can be trained to do both. I came from years of using the crabbing method with the luxury of reasonably high inertial aircraft like the Warrior which allowed an accurate transition in the round out, not much buffeting and brakes to quickly slow you to a speed where wind buffeting was not an issue.

 

By comparison RA aircraft are blown about like a leaf, and you make a very good point about the possibility of snagging a wheel.

I had a perfectionist for an RA Instructor and he retrained me on the Jab to cross control, lecturing me on the effects of a low wing with its side effect of  boundary layer, high wing, and biplanes where you had to allow for one wing in boundary layer and one not, and if there had been a Tiger Moth on the field he would have frog marched me across and made me learn the biplane too. So I had a unique knowledge of what to do and when.....which I've totally forgotten because he never provided notes and never stopped on one subject long enough.

 

Within the RA category I copped the J170 before the AD was introduced. This aircraft had longer and much more efficient wings than the J160, but used the same fuse couple length and same small fin/rudder as the J160. It was designed for better performance in the higher temperatures of the northern States, and no doubt did that well, but in the denser air of the south it was exciting, regularly running out of rudder authority on the way down to a landing. It was predictable, even on full rudder in a steady cross wind, but in gusting conditions, with no more authority you started to become the blades of a helicopter when a gust hit you. That situation could have been avoided by crabbing, but thanks to my instructor's frown if I tried it, I did learn to perfect a very flat approach which presented a smaller frontal area of upwind wing, and landing on the upwind wheel with the nose wheel only about 150 - 200 mm above the ground. Then along came the AD and turned it into a pussy cat.

 

[kgwilson]

If you have the choice in a strong crosswind, land on the grass. The risk of snagging a wheel is much reduced and if you are not straight the wheel will just skid sideways a bit before you slow and straighten up.

[aro]

I don't really understand the purpose of the lengthy wing down approach. The wind at runway level is almost always totally different to the wind at e.g. 200', so why put in the slip so high? it's not like you can hold the same correction all the way to landing.

 

With the crab method you are working with the natural stability of the aircraft. Momentum keeps it travelling in a straight line, which means that as the wind changes with gusts etc. the crab angle changes automatically to compensate. The drag is the same as normal, which means that you fly a normal approach, with the runway in a different place in the window.

 

When you round out over the runway, you align the nose with the runway and kill any drift with aileron. "Kick it straight" is not a good description. I don't understand the concern about timing either - how do you judge the timing to round out and stop the descent? If you don't do that before you hit the runway it would also be bad - but we manage to judge it OK.

 

With a wing down approach, you are fighting the stability of the aircraft. Every change in the wind needs a change in the amount of slip. Every change in the amount of slip changes the drag, which changes the rate of descent, which changes the power required. Then you fly through the low level wind gradient and most of it goes away. It just seems like a lot more difficult approach for no benefit.

 

[F10]

“TW The aileron on the into wind wing is actually up, not down. If the aileron were down, it would lift the into wind wing.”
Yes…but what I meant is touching down on one wheel in a wing down landing…the aircraft is still flying, most pilots use aileron to lower the other wheel. This roll often causes an out of wind rolling moment with down aileron, at the worst time. Watch the Oshkosh cross wind landings on U Tube….the wing down lads seem to get more out of shape immediately after touch down, to me anyway.

[F10]

And there’s more!🤓tricycle undercarriage, have the C of G ahead of the mains, this tends to help straighten the aircraft after touch down. I landed my Gazellie last Tuesday in an “angry” wind….was actually a bit late ruddering it straight, (I like “kick it straight”….it implies be positive and quick with the rudder, a good idea), she jerked slightly sideways, but I got the rudder in, immediately straightening her out…no drama of rolling moments and still having to rudder her straight….go the crabs!

Edited September 30, 2021 by F10
Typo

[F10]

“a low wing with its side effect of  boundary layer, high wing, and biplanes where you had to allow for one wing in boundary layer and one not,”

 

Not sure here. “Boundary layer” as I understand it, is the very thin layer of air, on the wing surface. Air molecules right at the wing surface, get dragged along with the wing. They brushed Tulcum powder onto a Mirage F1 wing, flew it to 600 kts, powder was still on the wing. There is a smooth laminar flow at the leading edge area, we then reach the “transition point” where the boundary layer becomes slightly turbulent and finally the separation point near the trailing edge, where reverse flow occurs causing separation.  The energy  characteristics of this boundary layer, and it’s ability to stick to the wing surface, determines the stalling characteristics of an aircraft. Boundary layer breakaway, defines the stall. So, as to bi plane landings, what may refer is the lower wing being more in “ground effect”, a different concept, than the upper wing? I would not have thought this would be noticeable as ground effect can be noticed by a pilot, up to half a wingspan (in theory, 3/4 wingspan) above the runaway surface. Anyone suffering insomnia….well this should have sorted it!😴