Teaching crosswind landings

[Timothy]

Why do so many ab initio instructors teach kicking off drift rather than wing down, when the latter is easier, more transferable across types, safer and increases crosswind capability?

It does seem that people tend to "graduate" to wing down after a few tens or hundreds of hours after PPL, seeing its advantages. This "graduation" gives the false impression that it is a more "grown up" way of doing crosswind landings, whereas in reality it is easier*. So why not just teach it as the "only" (or, if you prefer, "best") way from the start? Is it a JAA/FAA requirement to teach the kicking method?

Timothy

* this is ironically analogous to the VFR/IFR situation. VFR planning and navigation is much more difficult than IFR, yet IFR is a "graduation" from VFR

[Fly Stimulator]

I agree with you about the relative merits of the two approaches.

My speculation is that the drift approach is taken simply because that is the most obvious way for a beginner to correct for a crosswind and therefore it offers the path of least resistance for both teacher and pupil. Given the obvious and well-rehearsed parallels with things like swimming or rowing across a river it is an easy concept to explain.

The wing down approach isn't so immediately obvious and requires a bit more co-ordination on the part of the pilot. Perhaps the blood-curdling warnings about the use of full flaps in sideslips in certain aircraft play a part in some cases too.

[Kingy]

I agree that the wing down method is the best. A couple of thoughts on why it is not taught more during ab-initio training..:

1. It is a crossed control manuver. No other crossed control things are taught during training as, alas, side slipping seems to be frowned upon by most instructers. Certainly my instructor (who was exceptional) thought that it took people a while to be comfortable flying with crossed controls and it was something that would come with experience. He was quite pleased when I insisted we do an hour of approaches right up to, and slightly beyond the limit of the aircraft late during my training. Frankly, it is a skill not needed to pass the PPL and as such, perhaps it's left out in the name of 'economy'.

2. Without wishing to sound bitter, a lot of training seems to be aimed at 747 jock wannabes with some instructers being the same, just slightly more advanced. I believe that big jets use a crabbed approach rather than wing down. Maybe these instructors don't want to teach 'bad habits...'

Having said all that, the crabbed method does work up to a point and is preferable in some aircraft. So if it works for you, that's fine!

Kingy

[Milt]

Cross Wind Landings

Recently inserted the following into a discussion on the subject

My mostly military experience on 90 plus aircraft has been as a fledgling, QFI, CFS, Experimental Test Pilot and Hercules Sqn CO.

Can't recall how we were instructed pre wings.

I do recall taking a Wirraway to the edge of its and my capabilities once as a QFI with a CAF cadet aboard.
There was 35 kts , a bit gusty directly across a selected runway. The wing down technique could not have worked as the extent of sideslip necessary was unachievable. So to take the Wirraway way beyond its normally accepted limits of maybe 15 kts cross component was both highly irregular and experimental. And there was I in the back seat.

It was a challenge I accepted and I soon found that success could only be achieved with a series of deliberate actions. The approach with about half flap had to be about 10 to 15 kts fast with the nose pointing up to 20 degrees off runway alignment. The flare involved increasing the angle off as speed subsided. Then only when absolutely sure of being a few feet above the runway would one deliberately push the wheels hard on to the runway at the same time as a pre learned input of rudder was used to bring the nose somewhere close to straight down the runway. Any delay in that deliberate process would allow the aircraft to take on sideways drift, which if allowed to develop to what appeared to be excessive resulted in a go round. Or as I found on a long enough runway a second hard touch down could be set up and executed, before going around for another try.

That experience set me up as a firm subscriber to the kick straight push on wheeler for any aircraft which only becomes a bit hairy if you have flared excessively high. Oh the poor undercarriages!!

A few things emerge on reflection. Prior experience and practice/training on the technique are essentials and that there is some familiarity with the control inputs necessary to push the wheels firmly on the runway simultaneously with the kick straight. The weight of the aircraft type will affect the rapidity with which that type will accelerate sideways during that short period of time between kicking straight and wheel contact.

Clearly much larger crosswind components can be overcome with the kick straight technique than the wing down/sideslip method. I would not recommend playing around with a combination of the two techniques as the kick straight method in extreme conditions relies on BOTH main gears immediately taking up the side forces during the tail high roll out.

Some aircraft such as the B52 have undercarriages that can be aligned along the direction of the runway as they are just too cumbersome to kick straight.

Navy spoil themselves by pointing the ship but the angled decks probably result in some cross wind. Any Navy comments??

[Timothy]

Clearly much larger crosswind components can be overcome with the kick straight technique than the wing down/sideslip method.

This is not at all clear to me. Pushing the wheels on in a wheeled landing in a tailwheel aircraft is easily acheived, but you cannot do the same in a nosewheel type without risk to the nosewheel. I wonder if your advice is only directed at tailwheel types? (Though I note that you mention several nosewheel types.)

That leads me to wondering if the syllabus requirement for crab and kick dates from tailwheel days. Let's face it, the whole PPL syllabus attitude to GPS and radio nav dates from pre-war days.

My aircraft has a demonstrated component of 25kt and I can "easily" cope with 35kt with wing down. I would be loathe to even try kicking at that component.

I wonder which technique test pilots use for certification...they are supposed to emulate the typical competent pilot rather than the steely eyed superman.

Timothy

[jtr]

as the B52 have undercarriages that can be aligned along the direction of the runway as they are just too cumbersome to kick straight

The 330/340 777 and 747 are all more "cumbersome" than the B-52, yet seem to go ok without main wheel alignment systems.

[Whirlybird]

I discussed this with someone recently, and I'm pretty sure I got told that you wouldn't want to use wing down in a C150 or similar in a strong wind; can't remember why though. The person I was talking to seemed to think you needed different techniques for different aircraft. Anyone know? I really would like an easier way of doing crosswind landings. I don't mind kicking it straight - I'm a helicopter pilot; I have feet! It's the crabbing it in at an angle that I really find hard to estimate accurately, and hate, in a strongish wind.

I think I've also heard that you have less control with wing down in gusty conditions or windsheer; is this the case?

[Timothy]

Whirly

With all respect, it's these "I've been told", "everybody says" things that seem to be the problem rather than the solution.

As you know, I have flown a wide variety of types, small/large, metal/fabric, nose/tail, high/low, jet/piston, bi/mono (even a tiny bit of rotary ) and everything I have flown is easier wingdown than crab.

(I have not flown 7x7s, which I believe prefer crab.)

But certainly C1x2 and Piper Cub (both high wing) are far easier wing down than crab.

Timothy

[Final 3 Greens]

Timothy

I've observed an x-wind autolanding from the jumpseat on an L1011 and the a/p crabbed in to about 100' agl, then went to wing down!

As to why crabbed for PPL, I guess you will have to ask the CAA.

My instructor was very clearly of the opinion that it was because there were no crossed control manoeuvres taught on the syllabus.

Personally, I've always preferred crab/kick off, because it seems very natural to me, but I guess that we are all different

Also, my experience has been gained mainly on nosewheel singles, maybe I would take a different view if flying multis.

As an aside, has anyone read a POH that declared whihch method was used for the crosswind landing demo?

[KCDW]

Timothy,

quote:

That leads me to wondering if the syllabus requirement for crab and kick dates from tailwheel days. Let's face it, the whole PPL syllabus attitude to GPS and radio nav dates from pre-war days.

Not sure about that. You'll find many if not most tailwheel pilots going for wing down. Certainly on my taildragging course its the prefered option.

Reading "The Compleat Taildragger Pilot", the author goes on at some length (devoting a whole chapter and appendix) endorsing wing down over crab/kick out.

It is probably not taught on PPL in order to keep things simple, and to help keep the syllabus achievable in 45 hours.

My tailwheel course has been a breath of fresh air... the joy of cross controls ... slide slipping, that's something else...

[Genghis the Engineer]

I've very much of the view that it depends upon type and it's characteristics.

Picking two types that I've a nodding acquaintance with, the CFM Shadow and the Lockheed L1011; in both of these the preferred method taught is wing-down. They share similar characteristics - lowish sideforces during the continuous sideslip, and a high wing and (relatively speaking) short span, allowing fairly comfortable sideslipped flight and a reasonable bank angle down to the ground.

Alternatively, take a long, low-winged motorglider like the G109b. Wing-down is totally impracticable mainly because if any significant bank angle remained during the landing you'd strike the wingtip. Also, it's got reasonably low lateral stability, so it doesn't try to drop a wing as you kick-off drift.

I've flown a couple of high-wing FW types, with very high sideforces during sideslip such that any significant sideslip during a wing-down approach becomes incredibly uncomfortable. This is bad-enough in a light sports aircraft but would be totally unacceptable in a passenger transport - so crabbed it is.


However, it is true that a lot of aircraft - most of the lighter Pipers and Cessnas for example - will happily accept either technique (checking C152 and PA28-161 manuals on my shelf, neither recommend any specific technique). My experience of flying both is that neither particularly favours either method, but the point I'm making is that that's not universal to light aircraft.

When I'm managing the assessment of a new aircraft type I'll insist on crosswind handling being (at-least initially) investigated with both techniques, and advice given in the POH. If the advice is "use whichever you prefer" then that's fine, but it's far from universal.

The "start crabbed and transition to wing-down in the roundout" isn't all that unusual as handling advice - usually where the comfort levels are such that you don't want to have to live with high sideforces for any longer than necessary, but there's a strong preference for structural or performance reasons for landing straight on one wheel.

G

[S-Works]

I was under the impression that sideslipping in a CFM Shadow was prohibited. At least that was what I was taught when converting onto one a couple of years ago.

Is this not the case?

Personally a prefer a combination of both methods.

[treadigraph]

Whirlybird,

I seem to remember reading an incident report many years ago in which a C152 or C172 had the engine stop after a prolonged wing low cross-wind approach... I can't recall the exact circumstances but the conclusion was to the effect of low fuel state plus the wing low approach had combined to cause fuel starvation. Oh, I think it landed safely and the pilot was able to restart and taxy clear.

So that MAY be the reason why.

[Chuck Ellsworth]

Both methods should be taught.

Different aircraft require different techniques.

I taught the two methods during the illusions created by drift lesson. Fly the runway at ten or twenty feet with wing down and maintain center line and fly the runway crabbing to maintain center line.

The creb method will allow you to land in the higher x/wind component on every airplane that I have flown.......sideways drift is not a factor on touch down if the thing is tracking the center line as you boot the rudder.

Chuck

[Flyin'Dutch']

Wingdown limits the amount of Xwind you can take as the amount of slip you can generate will depend on rudder effectiveness.

The slip which is created by doing the winglow method gives extra drag, which may be a good thing or not but will vary with the amount of slip, which inherent to this method will depend on the amount of crosswind.

A large crosswind will necessitate a large amount of slip and therefore a lot of extra drag. Not necessarily a good combination.

The crab method is the way we compensate for crosswinds in any other phase of flight.

However it does require you to kick the thing straight before you settle down on the gear. If you do it neatly you will hold the upwind wing lower.

FD

[Fly Stimulator]

I was under the impression that sideslipping in a CFM Shadow was prohibited.

So was I. The 1998 copy of the Series D & DD Pilot's Handling Notes I have says about side slipping - "This manoeuvre is to be avoided as it places unnecessary stress on the forward wing attachment points."

On the very next page however it addresses the subject of crosswind landings and says - "The recommended technique is the low wing towards the wind method, the upwind mainwheel touching first. The rudder remains very responsive to directional control."

[John Farley]

BAD MOOD WARNING

I wish people would not talk about best when the discussion is between two techniques. For sure one may be better, but it cannot be best. Best needs three or more – at least where I was brought up.

Sorry about that but I did issue a warning!.

Now to stuff that is a damn sight more important.

Many of the comments made on this thread may well be correct inside a particular set of conditions but some writers do not indicate those conditions thus implying their remarks are true in all cases when patently they are not. This is not a case of being overly pedantic, it is a case of not confusing beginners in our business with duff gen.

We are all old enough to appreciate a good landing is usually proceeded by a good approach, so it is worth considering the approach which will go on for some considerable time compared to the landing phase.

For all aircraft types there is literally no limit to the cross wind in which it is perfectly safe to carry out a crabbed approach. Neither is there any problem during the crabbed approach if you are hit by a huge gust – at least no more than there would be with the same gust during an into wind approach on the same type.

In contrast there will be a type dependant limit for the wing down technique because of the way it requires crossed controls. The crossed control technique has implications about stall margin and even in extreme circumstances for loss of lateral and directional control by flicking. Without installing special flight test instrumentation it is not possible to progressively establish (and therefore be sure of) the control margin that surrounds a crossed control approach. Of course there is pilot feel and experience but this can be fallible with any of us. There may be a temptation to use stick position to judge control margin but this in itself presumes a linearity of control response that may not exist at large deflections. But my main concern regarding a crossed control approach is the effect of a big gust that could lead to one instantly going outside the boundaries of control.

Before I get any further up the nose of those pilots who prefer the wing down technique, may I make it clear that I agree it is not in the least hazardous in moderate cross winds and moderate turbulence. But it does eventually have limits whereas the crabbed approach does not. And anyhow what is moderate?

Now to the landing. Some aircraft configurations are prone to damage on touchdown (even without a crosswind) if the gust level is high. For example low wing airliners with podded engines can tolerate only a small bank angle at touchdown or they will scrape a pod. Any tricycle undercarriage aircraft will be very happy to land mainwheels first with some crab still present as the drag from the gear being behind the CG will smoothly reduce the crab. Quite the reverse is true of course with a tailwheel aircraft.

Now to the biggest problem of all. In a strong crosswind landing there is a nasty area between the stabilised approach (however that has been flown) and the aircraft running along the ground with enough weight on its wheels and enough friction from the surface to resist the cross runway force applied to it by the wind during roll out. Until that state has been reached some downwind drift will occur as soon as the approach crab or wing down angles are reduced. How many seconds this partial control of track goes on for is very type and pilot technique dependant so there can be no valid generalisations.

Given all of the above it does not surprise me that basic instruction teaches the crab technique.

On a personal note I have only once flown in a very strong gusty crosswind where I was greatly concerned about my ability to avoid a crash. At a guess the wind was probably twice the sensible crosswind ‘limit’ for the type. It was an airshow at a large US base and involved three different WWII open cockpit single engine US tailwheel training types with which we had agreed to do a formation display. Pretty obviously we decided that we would do a stream take off and a stream landing. We all felt the landing was going to be the real problem.

We were wrong - the landings turned out to be a doddle because we briefed that we would just keep flying the aircraft smoothly and gently until they were down to taxy speed. We felt it important to do NOTHING SUDDENLY - and in that context to kick off drift IS doing something suddenly. So we all used the crabbed technique for the approach and then flew low along the runway gradually reducing the crab with wing down. Of course we had the luxury that runway length was never going to be an issue so we just flew until we had got one wheel on the ground still with wing down and then very carefully increased the weight on the wheel, then wheels, by reducing power and speed watching like a hawk for the slightest tendency to swing. In the event we all had no problem. But the takeoff was another matter, once you are using full into wind aileron on the ground roll and the wing tip starts to rise you have no alternative but to snatch it off the ground and let it weathercock. We all found this and we had not briefed for it. A most unpleasant feeling. That experience taught me that the safe cross wind limit could be lower for takeoff than landing – something which had not occurred to me before.

Sorry to bang on so long, and in the end I don’t think I have actually said much that is new to this thread.

[G-SPOTs Lost]

A lot of A/C types have been mentioned here. Just one point that may need reinforcing for some is that the Manufacturers have mentioned that sideslips with flap should be avoided at all cost.

I'm not at work but I'm pretty sure the 150 with 40deg Flaps is one, and thats a type thats already been mentioned.

A problem with the flaps masking the elevator I believe.

Having said that you could always reduce the flap it all depends on R/W length and the conditions on the day.

As somebody said above no right or wrong.

[Shaggy Sheep Driver]

Sorry to bang on so long, and in the end I don’t think I have actually said much that is new to this thread.

I don't know about that, but you've crystalsed a few things for me, John. What have I learned from your post?

1) I sort of knew from experience that a crabbed approach has no crosswind limit whereas a crossed-controlled appoach has type-dependant (and pilot ability) limits and that envelope can be compromised by gusts. Your post crystalised that for me.

2) Don't do anything sudden. I know I have in the past done sudden kick-offs with associated untidy arrivals, and maybe I should think about that.

3) Take off can be a bigger problem than landing. Again, something I'd not thought through, but I can remember take offs in the Chipmunk where it's started to go pear shaped and the answer has been to haul it off, stay in ground effect, and let it weathercock while building up a safe climb-out speed.

Thanks John. Wise words as usual; thanks for sharing your experience. How's the book coming along?

SSD (Vince)

[Timothy]

John

As I mused earlier, I was wondering what they taught you at Test Pilot's School about technique when determining maximum component? I am really thinking about trike spam-cans here, let's say from C152 to PA31-310.

To give some background, I am surprised that the demonstrated component in the Aztec is as low as 25kt, as I find it quite controllable, nay docile, up to the mid thirties (my maximum has been 34kt and that was no great feat of heroics, just the application of exactly the same wing-down technique as usual but more so.) I have run out of rudder at 200' when trying to go cross controlled for a surface wind of about 30kt, but I just went back to crab and then tried again at 50' and there was no problem at all. But then I have flown almost nothing except the Aztec for seven or eight years and maybe they have to set sensible components for someone who is low hour and/or swapping between types?

So what criteria were you taught to use for determining what an average pilot could cope with? I am not sure if you tested anything but the Harrier, which is why I say "taught to use" rather than "used". Forgive me if you have 10,000 hours test flying spam-cans!

Timothy