Crab on approach until you have to straighten to land. As you probably shouldn't land sideways (bad for the undercarriage) you have to straighten out which will require dropping on wing and using opposite rudder to stop the turn. If you are carrying pax it's much nicer to be sitting up than falling over to one side. Much easier to maintain a wind-corrected heading than a bank angle.

Sorry, Papi, I could have made it slightly clearer where I agree with you and where I don't.

I agree that if your manual states that there is a limit and you don't comply with it, you are almost certainly not insured since compliance with the POH is normally a requirement of insurance.

I also agree that if your club's Flying Order Book gives a limit and you don't comply with it, you are almost certainly not insured since compliance with the FOB is normally a requirement of insurance for club aircraft.

However, what I do not agree with is that the "demonstrated cross wind" is a limit which must be complied with. Many aircraft manuals give a demonstrated cross wind, but do not give a limit. And in these cases, if the aircraft is privately owned, or if it is a club aircraft and the club does not set a limit (or you are exempt from any limits the club sets), then there is no limit. The example I have given of a C172 (complete with a quote of the relevant section of the manual) is an aircraft which does not have a limit.

My club, which operates two C172s, imposes a limit of 8kts for solo students and 12kts for PPLs for depature, and the same limits on forecast winds for landings, with a warning that if the wind becomes outside these limits during flight, consideration should be given to diverting. Solo students and PPLs must comply with these limits to be insured, and we will not rent aircraft to anyone if the wind, or the forecast wind, is outside these limits. However, we do not have a limit for holders of CPL or higher licenses.

Since I hold a CPL, I regularly, legally, and being fully insured, fly in cross-winds far exceeding the 15kts demonstrated limit of the aircraft, to carry out trial lessons for example. I will also teach students (with an appropriate amount of prior experience that they will benefit from it, of course) or existing PPLs how to handle these strong crosswinds, because a) it will give them confidence to improve their personal limits up to the club's limits, and b) there is always a chance that the wind will do something other than forecast during a trip, and the wind will be outside their limits when they return. (The club's rules do not prevent them from making an approach in these conditions, they merely caution that consideration should be given to diverting.)

To the best of my knowledge, the rules my club sets are fairly typical of the majority of other clubs.

FFF
-----------

I prefer the crab method as well, but I have to disagree a bit with some of you saying that you should lower the wing when straightening out. It is not completely wrong, but you should use enough opposite aileron to level the wing, and THEN if you start to drift you should lower the wing into wind. I agree that in strong x-wind conditions you probably always have to add that extra correction...

A reason why I don't like the wing low in for example a c-172, is that on many 172's there is only one static port on the left hand side. And the wing low is a slip condition, and in a slip you will have over -or under reading IAS with only one static port, and over read of the IAS is not something you wan't on final if not aware of it.

for a novice: align the nose, then use aileron.
if you know the plane well, and know how much rudder you have to give, the crab method is OK.

guys, whatever method you use is OK, as long you are happy with.
the most dangerous situation is people turning from base to final and using to much rudder.this is a spin departure, ...

Thought that may provoke a reaction (and then couldn't get near a computer for 24 hours - drat!!)

.

Wrong.

It is a demonstrated limit, not an absolute limit. A test pilot will only have a small window to test in, if the crosswind available was only 15 knots that day, then that is what the demonstrated crosswind limit will be.

.

Wrong.

It is not "technically outside the limits of the aircraft, see above.

It is limiting when you run out of rudder authority. Simple as that. If you do, then you go around.



I agree. Though the limits are far more likely to be personal limits rather than the aeroplanes limit. The ability to turn round after you have reached the halfway point is also a good thing, but irrelevant to this thread.

Outside what limits? If it is outside my limits then I will stay at base, otherwise I will go. My limits are a lot lot less than the aeroplanes, but the aeroplanes limits are far far more than the demonstrated.

I agree that if the manufacturer sets a cross-wind limit, you must stick to it or you will not be insured. Also, if you fly a club aircraft, you must comply with any limits in the club's Flying Order Book, or you will not be insured.

The POH for the aircraft I fly the most only gives a demonstrated crosswind. What's more, the manual explicitly states that this is not a limit!



Very sensible.


You are talking about club aircraft and club aircraft only. It is for the clubs sake that these limits are imposed, due to the varying skill level of the renters. However, it does NOT imply that you cannot legally fly the same type outside of the club, therefore the demonstrated limit is not limiting nor illegal, unless a club/school has imposed rules to safeguard themselves.


Nobody is saying that they have no respect for the weather or for their aircraft. They are saying that a crosswind needn't mean a cancelled flight as long as it is not above the pilots limits. "Playing with fire" is a little of an extreme way of describing someone safely and sensibly pushing their limits (and therefore their skill level) up.

don't get a reputation for being a risk taker...
 

Guys, whatever you do, be careful whatever you do. It's not a testicle-size competition. If you want a future in professional aviation, I'd recommend you not try to land a light aircraft beyond your or the aircraft's limits. I'd suggest your limits should be lower.

My 2 cents, personally found x/w landings to be a nightmare until I was taught the wing low technique. Later as I gained actual skill my judgement improved and could use either efficiently. Was inclined to teach the crab/kick straight method when instructing.

FFF and Andy_R are correct, the Demonstrated Crosswind is not a limit, but a Demonstrated Component. It would help if people didn't refer to it as a limit- unless it is refered to as a limit by a particular aircraft flight manual.

I also add (from memory) that in Cessna aircraft the Demonstrated Crosswind figure is not found in the limitations section but the Normal Operations section of the Flight Manual (if someone has one handy colud they confirm this?).

I believe also that the Demonstration can be limited by the conditions encountered during the test flight phase- if the cross wind component never exceeded value X then that that is where the notation occured, some aircraft types have had their crosswind component uprated when retested in stronger conditions.

Dear King Rooney,

Have you considered switching to OAT as a different FTO as you seem so unhappy where you are? :E

MB

I believe the difference between the apparent difference between demonstrated cross wind componets is the method which they are obtained.

Some are demo'd without using the rudder other's do use the rudder.

The ones which do use the rudder are usually listed as limits and the ones without are demonstrated.

I presume these days its all liability.

There seems to be many theories on this. As Sgroogee says, it just happens to be the strongest crosswind demonstrated to the authority during the certification phase. If the wind didn't blow then it is low, if it is then it maybe the limit of the aircraft, but you don't know that. Therefore, I don't believe the demonstrated limit actually tells you much at all about the true limit of the aeroplane. My experience is that I am more than capable of landing in excess of the demo limit on some aircraft and am not really upto it on others. That isn't a recipe for gonad growth, simply an understanding of what the numbers mean.

FYI
http://www.gulfstream.com/product_su...GIV_OIS_09.pdf
http://www.gulfstream.com/product_su.../GV_OIS_01.pdf

Just to try and address some of these technicalities a bit further.

Crosswind techniques:
In truth there are 2 methods,

1) Side Slip technique. i.e. Windward wind down for finals (The amount being dependent on strength of xwind component). This counters the drift and allows for an approach straight in on the runway 'heading'. In other words no adjustment needed on roundout.

2) The Combination technique. (I find this works best for me). This involves a 'crabbed' approach. i.e. You track the centre line on finals with the a/c weather cocked into wind. As you reach roundout, you straighten the a/c's heading to the runway heading and then lower windward wing.

There isn't really such a thing as just a 'crabbed' approach. Remember there still remains several seconds during round out before you touchdown. During this period the crosswind will move you off centre line or worse still. How is this counter acted? By roll. i.e. Windward wing down. The other important reason for lowering the windward wing is to enhance stability and ensure you don't get blown over, especially in gusting xwinds. Windward wind down ensures the wind blows over the wing and the rest of the a/c. Windward wing not down means wind blowing under the wing. Not good! (It's sometimes good to lower the windward wing very slightly on finals as well in gusts. Even if crabbed).

Just to add, on a point of order. The phrase 'kick straight the rudder' is a bit misleading and shouldn't be used. You don't 'kick' the rudder straight. You promptly & smoothly starighten with rudder as not to over do it. Then you continue to maintain runway head with rudder control until the roundout is complete and you have touched down. ;)

Regarding rudder authority: The selection of runway should deal with this. Imagine landing on a runway 360 and you have an xwind say 15kts coming from 090. The wind blows on the right-hand side of the empennage and naturally weathercocks the a/c back into the wind. On roundout, you apply left rudder. The point some of you are raising is that you may 'run out' of left rudder before the a/c is straight. Remember on a single engine the slipstream from the prop blows in a clockwise twisting motion around the fuselage of the a/c, which means it eventually hits the left-hand side of the empennage, giving rudder more authority. (Hence right rudder during a standard take off!)

Of course, you lower the windward wing so rudder authority is not an issue and the ailerons then counter the drift). If you tried landing on runway 18, things would be more difficult as the slipstream and the wind would act on the same side of the empennage and reduce your rudder authority unnecessarily.

Obviously most a/c have a max 'demonstrated' xwind limit. The Katanas we fly have 20kts. You can breach the limit and have a go, but not really advisable as there is only so much you can do!

Hope this helps. Crosswinds can be a difficult thing for a pilot to learn. You are moving the a/c on all 3 axis all more or less at the same time. It took me a while to get the hang of these. I used to fear a good xwind. Now they're a nice challenge. Good landings are always satisfying, but a good xwind landing is even better.

REMEMBER THOUGH. Dont get sucked into getting it down if things get difficult. GO AROUND and have another try!

Here's a link for your viewing pleasure. Technique is a bit different but the principle is the same..
http://www.linhadafrente.net/bin/Pousos.wmv If it doesn't work then type in '777 crosswind landing' into yahoo and access it from a different source.

Enjoy :ok:

It depends on how wide the runway is and yes, the C-172 can land with considerable drift on and stay on the runway.

What I like about wing-down is that you get a clue ahead of time when there's not enough rudder to keep the plane lined up. Mind you, there will be less wind at the surface.

If the wind picks up another 10 kt or so, do you know where to find another runway that's pointed into the wind?

Once you're down in a wind over 20 kt. and still on your wheels, be very careful about taxying downwind.

As for the FTO, they may be used to the prevailing winds and if you have demonstrated acceptable landings dual in similar conditions, they may have decided that you're up to the job. Students botching landings gets the attention of the CAA and raises the insurance premiums.

Demonstrated limitations
 

Re comments about DEMONSTRATED limitations, I flew on a twinjet fleet where we'd two different marks of engine, one more powerful than the other.
Curiously, Vmcg on the lower powered variant was higher than on the more powerful machine :confused:
Boss reckoned it was entirely due to test pilot assessment - don't think more powerful had more rudder authority.
Anyway, I just flew it - didn't have to make one.

Supercruise,I would disagree with that.

A crabbed approach involves entering the flare with crab, then just before the wheels touch down kicking it straight with rudder - sorry, "promptly & smoothly starighten with rudder as not to over do it" ;) As the rudder is applied, a little oposite aileron is required to keep the wings level, in order to counteract the secondary effect of the rudder. The landing is made with wings level, both main wheels together, before the aircraft has a chance to start drifting. (Obviously a very light aircraft would start drifting very soon after straightening up, which makes this technique very difficult on some very light aircraft.)

The key here is that the landing is made wings level.

If the rudder is applied too soon (either deliberately or due to a slight lack of judgement, makes no difference), the aircraft will start drifting if it is not corrected. The correction which is made is to apply more into-wind aileron to lower the into-wind wing. As the aileron is applied, more rudder is required to avoid the yaw which occurs as a secondary effect of the rudder. The landing is now made with the into-wind wheel first, followed by the other main wheel, followed by the nose wheel. This is the Combination technique, and it is slightly different from the crab technique in that the landing itself happens with one wing low.

However, I think lots of people use the phrase "crab technique" to refer to this one, probably because they have never seen a properly executed crab technique and therefore don't appreciate the difference. This was certainly the case with me, until I did my FIC. In around a 25kt cross-wind in a PA28 my instructor demonstrated a crab technique properly - it was a work of art, and not something I've ever been able to replicate since.

FFF
-----------

FlyingForFun,

Interesting comments & you sound like someone who has alot of experience of this. However, just a few more points. Forgive me for quoting you out of context or being too subjective but...

"The landing is made with wings level, both main wheels together, before the aircraft has a chance to start drifting".

"The landing is now made with the into-wind wheel first, followed by the other main wheel, followed by the nose wheel".

A bit of a contradiction in terms?

Before the a/c "has a chance to start drifting". That's rubbish.

Not even the best pilot can really everytime on a perfect roundout with more or less instantaneous heading alteration (rudder) and touchdown. Lots of xwinds variate and as someone said 'they reduce as you approach the surface'. Well generally, that is what is expected. Once well below the friction layer on approach though things could happen that are difficult to predict, especially at a point of pilot high workload.

Many xwinds variate through a range of degrees. Everyone has seen examples of this from the socks as they come in. Anything could happen. You may float, bounce, a gust may come along and tip your windward wing up, sudden windshear etc. I landed in approx 12 kts xwind the other day. The x component increased as I got to the surface! Generally unexpected.

Why rely on "chance"? Why not follow a preventative method that stops last minute drift and enhances stability? (Your correct in that you may realise there is very little drift during roundout hence so little windward aileron is required that your wings are almost level, depending on how much you are countering secondary effects). Why do you need to land with wings level if there is still drift?

Why not follow your second correct statement and land with windward wind down (hence windward main down as well). Gosh we even see the Saabs (commercial) doing it whilst we wait for RWY entry. Don't ever rely on chance unless there is a technique that removes it from the equation!

Not going to enter the argument about this and that as that would be a recipe for getting no-where. However I do recall learning many things about crosswinds years ago on Types such as SuperCubs on towing operations. Probably some of the things I did then I wouldn't do now ... ?

Couple of things to consider -

(a) the Design Standard will define a minimum crosswind for the certification exercise. If the test program gets more, fine, but practicality may become a limiting factor

(b) the demonstrated value may have been able to be pushed up had the program found a tad more crosswind .. the problem is the line pilot doesn't know what the TP found and how much pad there might be. I can recall a quite nice line of singles which came on the market quite some years ago. The demonstrated crosswind was quite low (15 -16 kts or so as I recall) and we redid the certification for the crosswind limit. This particular design had an interlinked aileron/rudder and we ended up deciding that discretion was very much the better part of valour at around 18-20 kts if memory serves me correctly .. that few knots increase definitely presented some limitations for handling in the landing flare and roll out.

(c) there may be other dragons waiting in the far reaches of the known world for careless would-be TPs .. consider things like tail blanking and uncommanded pitch excursions .. just what you might not want to experience during the flare ?

lol..

Good points John.

You're not suggesting we are careless would-be TP's are you? ;)

.. Heaven forbid, mate.

On the other hand, I have to admit that greasing a strong crosswind landing on is a matter for great delight and satisfaction. Used regularly run down to a crosswind landing at one hub airport in another life ... 25-35 kts often was the order of the day and a fistful of throttles made for interest.

Awesome...

Supercruise,No, I am describing two different methods of landing. The first line you have quoted from my earlier post relates to a crabbed landing. The second relates to either a wing-low or, in the context in which I intended it, a combination landing. No contradiction since the two quotes are in two different contexts.Because both statements are correct in their context. Your assertion that landing with wings level is incorrect and chancy and that wing-low is the only correct way because "we even see the Saabs (commercial) doing it" is not true.

And it's not just me who thinks that, either. The same view was held by Wolfgang Langeweische, who I think is universally recognised as one of the experts in handling aircraft. I quote from his book Stick And Rudder, where he describes the crabbed method as it relates to a crosswind from the left:(The emphasis is added by me.)

I would guess that the reason you see Saabs landing with a combination technique is because it is easier than a crab technique: as I said earlier, I've only ever seen one person who can reliably use a crab technique properly without it becoming a combination technique. But it is is possible, because I've seen it. Langeweische also says it is possible, and remember he is talking about tail-draggers, where getting it slightly wrong could well result in a ground-loop - so there is less need for absolute perfection in modern aircraft than there was when he wrote this.

FFF
---------------

Sounds like the Mooney 201 and friends, introduced around 1980. The max demonstrated is 11 knots (exactly 0.2 Vso). I also remember 17 knots as being the number that stuck in my mind as delimiting the routine from the ... interesting landings. Crosswind take-offs were challenging too.

I think FFF is on the right track:D here.

I always ask (or state myself) whether people are going to use the 'wing down' or 'crab' technique if we are going to experience a serious x-wind component, as it saves me a short period of uncertainty as we approach the runway.

I have to say that 99% of those who 'crab' are, in fact, using the 'very late wing down' method, much as FFF has described. I also agree that the perfect 'crab' landing involves achieving alignment of the centreline of the aircraft with that of the runway, at the moment of touchdown (the process having started shortly before). After touchdown the wings are level, being kept that way by an appropriate amount of into-wind aileron.

I have to say (and this is personal to us all) that I prefer the 'wing down' approach as it is stable and you don't have to guess where the main gear (or nose gear, depending on how you fly) is going to end up. Also, showing my yellow streak, if you are running out of control at 200' with the wing down, you get a chance to throw it all away earlier than when you start drifting onto the grass at ten feet...

FFF and Fullwings,

Why do you mention that most crab landings are actually a combination of both crab and wing down methods. This is not true. As you straighten up using rudder you also use opp aileron into wind, however you touch down with both main wheels and with the wings level.

The main disadvantage of the wing down method is that the pax will be uncomfortable during the approach, leaning over to one side seems crazy to me.

Crosswind take offs are more limiting and demanding anyway, although most people thing the landing is the most difficult.:hmm: its not.

Marsman,

Impolite sentence deleted .. keep it nice, chaps ...

You will only touch down wings level if you kick the drift off at exactly the right time, otherwise you will need a small amount of wing down. This is basic PofF. Nobody can repeatedly get this right. Neither method can ASSURE a wings level touchdown unless you never kick the drift off which I strongly recommend against. It twists the gear and even on a modern jet will result in a very uncomfortable feeling. (I've been there!)

marsman: FFF and Fullwings are closer to the mark about what actually happens with most attempts at crab landings- whether intentionally or not. This is particulary true of the majority pilots. However the initial intention is for the landing to result both main wheel touching down at the same time, tracking the runway centreline.

Regarding my earlier post supercruise593 is correct regarding the "kick straight" part, after the initial "kick" most students would try and land normally, then wonder why the squeeling was occuring, as the aircraft weathercocked back into wind, and landed sideways.

Scoogee,
What say is perfectly correct however I dont believe this is repeatable several times in a row. The only way for the 'average' pilot to get the a/c on the ground is to use 'very late wing down' as described previously. This is not therefore a wings level landing. The only way to land wings level is with no x-wind or complete luck-FACT

Q. Why does a B747 have 4 sets of main undercarriage units?

A. Because it needs them to acommodate the aircraft weight, particularly during Landing.

Q. Would it be advisable to use only one quarter of the undercarriage units to absorb the landing load?

A. NO!

You figure out the rest, and the preferred landing technique:*

Regards,

Old Smokey

OS -- The 4 sets of 747 MLG bogies are there for takeoff and aborts at max weight. Landings, generally at half the weight, can be done on just the body or wing gear -- although a landing on just the body gear is best done with a minimal crosswind.

There is considerable vertical travel on the wing gear oleos; however, the limiting factor in bank is the outer engine pod.

Also the rear axles of the bogies hang down; so, there is a complex gradation of weight transfer from lift to the gear as the various axles and bogies come into contact and the oleos compress.

Bottom line is that the first gear contacting the runway does not immediately assume the entire landing weight -- assuming a reasonable descent rate.

Agreed... in a lighty. However in a heavy, kick the rudder in around 100ft to 50ft AGL and keep the wings level or with a VERY slight wing down. The inertia of the aircraft will maintain centreline and you won't have a pod strike.

RatherBeFlying,

I read loud and clear where you're coming from, and agree with you.

The intent of the suggestions implied in my post was that it's always preferred to not take any part of the aircraft all of the way to it's limits (e.g. allowing one set of landing gear to do the work of four), hence the use of the words "advisable" and "preferred" in my post.

Regards,

Old Smokey

As a student my instructor insisted I use, what has been described here as the ‘combination’ xwind landing method. His view on a ‘wing low’ approach was “Why cross your controls and increase your stalling speed when you are already low and slow?”
I have read this thread with interest but have not seen any mention of this.
He did eventually teach me both, but always warned me to keep my approach speed a little higher when making a ‘wing low’ approach compared to making a ‘crabbed’ approach.
Was he wrong?
Regards,
W.B.

Neither type of approach is "wrong" or "right." Use which ever you feel comfortable with and which is sensible for the type you are flying.
Most jets with underslung engine pods aren't very good at wing down. It tends to get expensive very quickly! A Cessna is a bit more forgiving.

One question for everyone. Why is the demonstrated cross wind limit on the 152 and 150 different?

Could it be due to the difference in techniques of the test pilots? Answers on a postcard.

Try landing any of the Cessna Tailwheel types without applying sufficient into wind aileron. Crossed controls are the order of the day for almost all landings except nil wind conditions.
Transition from crab to wing down is a must, and is called the combination method. If you do not roll in aileron and apply opposite rudder, you will surely start to drift.
One advantage tailwheels types do have, is that they can be held on at any speed. It is quite possible to hold them on at 100kts, although it is a bit hard on the gear. With a X-wind at the higher speeds, you would still have to hold into wind aileron and opposite rudder to maintain your line without drift.

Wing down Vs crab? It's down to what you've been tought and what you're used to. I once checked out in a school in the States prior to renting an aircraft. The CFI insisted I did the wing down method as that is what his school did and 'it was superior'. After cocking up a couple he declared that 'I had obviously never flown taildraggers' (actually I had about 1500 hours on them) so I demo'd a perfect crab method on the other runway with 25 knots of cross wind. He conceded.

Also, what id a limit? If you look at a lot of aircraft's POH (esp American ones) the crosswind is a 'max demonstrated cross wind', in otherwords it's the maximum the manufacturer has tested to. It's up to the operator what he does with that limit - whether he want's to treat it as a limit or not. I flew a very large jet with two companies. One treated it as an absolute limit, one left it to the pilot's discretion.

Dan, I agree that is not an absolute by any stretch of the imagination.
There is a time and place for each method of dealing with X-winds. I use either as required in the 185.

Sorry for the SLF intervention,
just found this link in the spotters forum, nice demonstration of crosswind landings :ok:
http://www.youtube.com/watch_fullscr...ind%20landings

Listen, look, emulate, learn (hopefully)
 

KR quote:
'Keygrip however, I do not like your patronising tone a great deal, there really is no need.'

If Keygrip is who I think he is then he's the best instructor/examiner I've ever flown with, bar none. In any case he was just trying to give you some advice which will save you breaking an aeroplane, boosting all of our insurance costs and preserve what seems to be an unjustifyably large ego intact.

To (miss)quote another aviation guru ' most common cause of a broken (aeroplane) is to have been talking when you should have been listening'..... Hope this helps.

PF

PS I find that most students in both gliders and aeroplanes seem to get the combination technique quite quickly - i.e. crab + a touch of wing down in the flare etc. The wheel doesn't take all of the weight because the wings are still producing lift. When wing stops producing lift you loose aileron authority and the other wheel gently touches the ground- evey time. Works on taildraggers and twins too. Admitedly I've never tired it in a 747, or at 90 kts.

Bookworm - I was thinking the same thing as I was reading John's post.

If I remember correctly, your aircraft was a later J. Out of interest - was the 17 knots transition level with full, half or zero flaps? Did you have any personal guidelines for how much flaps you'd use with different levels of crosswind?