bank into wind during strong cross wind takeoff

[Bungfai]

My B777 instructor told me not to bank into wind during strong cross wind takeoff, because it will induce roll spoilers to extend. But I still think that we must give a little bank into wind to keep wing level for high swept back wing aircraft. My instuctor told me that to bank into wind is the thing of the past. Any comments.

[Basil]

I haven't operated the 777 but on all the swept wing types flown, we have applied sufficient into wind roll control to prevent the upwind wing from lifting.
NO BANK, just enough control to keep wings level. We were aware of the control movement which would cause spoilers to extend and usually avoided entering that range.

Once airborne AND with an assymetric engine failure, 5 deg bank into the live engine is usually permissible. I believe that some regulatory authorities take this into account when establishing Vmca.

However, your instructor will be qualified to train on your specific type. What does your flying manual say?

777 trainers - what's the gen?

[Bungfai]

Thanks, my manual doesn't say any thing about it. Any of you guys with B777 can give me some ideas ?

[Driver 242]

If your instructor tells you something, why not accept it?
If you want to pass, start doing what your instructor says.

In general for most jets, hold the crab, kick it straight in the flare and land on Both mains at the same time. That was the way Boeing designed the aircraft to be operated.

Here are the Boeing boys testing the 777. Yes it is a bit windy!!!!
http://www.youtube.com/watch?v=EDfWXzd3Zfk

[Dani]

Your FI is most probably right.
Problem is, that if your spoilers are extended, you increase drag, and if you watch your wing once from pax row 40ish, you see how big your spoilers are.

One could argue that you like to have your wing straight and wish to have safety margin against gusts on take of roll. But you will move into territory without protection from certification.

Today's swept wing are not as prone to roll anymore. If you take off on a really gusty crosswind day, you will rather feel the big force of yaw, produced by the crosswind blowing into your huge tail fin. If you remember your sim lessons with engine failure, you see also that this swept wing aircraft is very forgiving (not only because of the wing).

So, cheer up, and enjoy the good handling qualities!
Dani

[misd-agin]

Ask him what Boeing says on the subject.

The answer I heard from Boeing was no input until needed to prevent the upwind wing from lifting.

That means very little input, and then only as speed approaches rotation.

Many line pilots put way too much input in on takeoff roll IMO(in my observation...).

[Capn Bloggs]

So rolling like this on liftoff is OK?

http://www.youtube.com/watch?v=J9BgwLbPIwI

If he were to lose No 1, things would get sporting.

In my jet, the roll spoilers don't start popping up until more than 30° of control wheel rotation, meaning you can have quite a bit of aileron in for liftoff to keep the wings level before you start popping the spoilers.

[Jimmy The Big Greek]

ooh, that was so cool videos with the crosswind landings.

I have one question. When landing a jet in crosswind. Do you correct for the crab after you have touched down??? I have always thought you do it during the flare.

[Dani]

after touchdown, it's the physics that do, not you...

More seriously: Some operators don't decrab at all, escpecially on contaminated or wet runway. Most producer recommend it during flare. I learned it to do before flare, because - if you do it during flare - you have to do several yoke/stick movements at one time, which might be difficult.

Dani

[ray cosmic]

Normally you give as much roll as needed to keep the wings level. Only a littlebit is normally needed, though. Like 1 or 2 units should do the trick.
I as well came from an operator where this was prohibited and you are skidding down the runway in heavy x-wind. Another operator tells me the opposite, and the take-offs seem to be more controlled. Performance is being used as the reason why not to do it, but it is not really a factor.
Try it in the sim next time.:ok:

[Kiwiguy]

Actually i was unimpressed by these test pilots in the youtube clips, since they made no effort to decrab at the flare.

The 737 is limited to 19 knots crosswind with minimal flaps and 23 knot crosswinds with 40 degrees flap. The limit applies to aircraft which are not de-crabbed. The limit is set not by the aerodynamic limit of the aircraft but rather by the strength of the undercarriage to resist hitting the runway sideways.

If the aircraft is de-crabbed to align with the runway in the flare then the risk is removed and theoretically if you use proper technique there is no limit.

I landed a Gulfstream Cheetah at Wellington's runway 16 in 45 knot winds gusting 55 knots from 240 degrees once. The crosswind limit on a Cheetah was 11 knots, but if you land properly it will handle that. The limit is on the undercarriage strength and not aerodynamic factors.

Wellington is a wind factory and it is not uncommon for Air NZ B733s to land with 50-60 knot crosswinds. Course the passengers often don't appreciate it.

Oh and PS: The rudder is used to equalise the drift. the aileron to slip towards or away from the runway as a form of minor adjustment to track the centreline. Always de-crab before touchdown, by kicking the ruder to point along the centreline.

[BOAC]

The 737 is limited to 19 knots crosswind with minimal flaps and 23 knot crosswinds with 40 degrees flap. - I assume these are company limits, since they are not Boeing?

We have 'drifted' somewhat from the original track which was about roll control during take-off. As 'misd-agin ' posted, I try to use what I need rather than any 'pre-set' concept. If I have to deploy the spoilers to avoid the wing-tip digging in I do.:)

[Jimmy The Big Greek]

I did not know this and I must say that I dont like the idea with not de-crabbing.

[Capn Bloggs]

I landed a Gulfstream Cheetah at Wellington's runway 16 in 45 knot winds gusting 55 knots from 240 degrees once. The crosswind limit on a Cheetah was 11 knots,

I'll bet your local aviation authority examiner wasn't watching! Since when have flight manual crosswind limits been able to be ignored if you de-crab?

I have heard that some Asian carriers do not teach de-crabbing. Probably because, as the videos show, the aircraft can handle it (provided the limits are not exceeded) and secondly, if you stuff it up and start drifting, you could end up anywhere. Given longhaul pilots don't do a lot of landings, "fly it on crooked" is probably not such a bad policy.

[Kiwiguy]

I'll bet your local aviation authority examiner wasn't watching! Since when have flight manual crosswind limits been able to be ignored if you de-crab?

Watching ?

My oath... My CFI was sitting beside me and we had a back seat passenger. A student pilot whom the CFI wanted me to show correct flare technique to. I have to say I was a little surprised we even flew that day. During pre take off drills holding short, when i checked control surfaces with engine idling we took off unintentionally. After we sorted that out the tower cleared me onto the runway for take off !

http://tvnz.co.nz/view/page/425829/842395

http://www.scoop.co.nz/stories/HL0408/S00185.htm

www.wwa.org.nz/Weather/How%20windy%20is%20Wellington.htm (http://www.wwa.org.nz/Weather/How%20windy%20is%20Wellington.htm)

(These links should work now)

[FullWings]

Bungfai, (are you bribing a well-respected aviation organisation? ;) )

On my fleet (777) the trainers tend to encourage a bit of into-wind aileron in crosswinds. Having observed and performed many x-wind takeoffs, I would say it's not a bad idea. You don't need much in the way of deflection - you're just trying to stop the upwind wing lifting dramatically on rotation: I suppose it's the difference between anticipating something or just reacting to what has happened. In the second case, people sometimes have a bit of a 'wobble', the severity of which depends of what they do with the rudder.

If you think about it, taking off in a jet with a big fin in a crosswind you have to apply a force to the airframe to counter the tendency to weathercock. At slow speeds most of this will come from nosewheel steering ("rudder fine") but close to and during rotation it has to be aerodynamic with the rudder biased to one side or the other. As the mainwheels leave the ground and the side reaction force from the tyres disappears, the aeroplane will start to move off the runway centreline. That can be countered by introducing a drift angle by gently reducing the rudder deflection to zero. The end result is being in balanced flight climbing out on the runway centreline... (well, sometimes!) In essence you are leaving the ground in a sideslip and uncrossing the controls as you climb away. The intial aileron deflection is bled away at the same time as the reduction in rudder.

Hope this helps!

[SuperRanger]

bungfai,
this is what my copy of B777 FCTM says. i took the liberty of underlining the relevant sentence.
http://i123.photobucket.com/albums/o310/palmiator/fctm.jpg

[Centaurus]

Kiwiguy. Which Boeing published document states that the crosswind limits as you stated are dependant on flap setting under normal conditions. Or are your figures only your specific company limitations rather than manufacturer´s limits? In addition, I find it difficult to believe that New Zealand pilots would land with a 50-60 knot crosswind component when the manufacturer´s limitation is well below that. Remind me not to buy a second hand 737 from a NZ operator..
Of course if what you meant to say is that Wellington has strong winds and Boeings routinely land with a 50 knot headwind component and not crosswind component, then that is understandable. Your comments on the landing of your light aircraft with 45 knot crosswind component either indicates you are a Walter Mitty nutter on these pages or you and your instructor should have your licences taken away. Certainly your light aircraft should be subject to an airworthiness maintenance check on the landing gear attachments if indeed you were foolish enough to land in such strong crosswinds beyond the manufacturer´s limit.

[Kiwiguy]

Centaurus I am not an airline pilot. I am merely an airport worker. I genuinely can't recall the document which I read about 737 crosswind limits, except the details I related but since I read this only in the last week i will retrace my steps and try to find it for you.

My recollection at the time was that it was either a Boeing document or someone citing from one. I will make the effort for you, because I found it interesting to note from what I read that the limit was not aerodynamic, but rather a function of what would break the gear if you fail to de-crab.

Put in a more accurate way, Mr Boeing would not certify the gear wouldn't break if you landed in an un-decrabbed manner above certain limits. Obviously finding the document will help us all have a look and an opinion.

The inference I took however was that if you de-crab in effect limit is not an issue. My humble opinion. Anyway you can take it from my equally humble efforts as a test pilot that this aeroplane (Cheetah) handles a damn sight more than the placarded limit.:8

I plead ignorance as a thirty something hour SPL at the time.

Whilst Wellington airport only sees 733s land in 50-60 knot crosswinds a few days per year, I can say I have had a ringside seat on the Ramp to many hairy landings and these appear de riguer at WLG. I suspect there is a lot of commercial pressure on these guys that if the airport company does not close the airport due to high winds (which it rarely does) then the onus is on pilots to defy their employer.

SuperRanger's document is very helpful indeed. Tongue in cheek I was thinking this proceedure is obviously written by the same test pilots who failed to de-crab in that youtube video earlier.

What it says however re-states what I mentioned. Ailerons just provide some slip to keep tracking the runway. Unlike these 777 jocks, I would de-crab before hitting the pavement.

PS Hey guys little request if you can help about 732 holding speed, please don't ignore my little post here... please?

Also this PDF file touches upon somethingelse which is relevant to the debate:

http://www.gulfstream.com/product_support/technical_pubs/pdfs/G2_G3/_OIS/GIII-OIS-13%20Rev%2000.pdf

That is, the crosswind limits on most aircraft are only the demonstrated limits and not the actual aerodynamic limits. Thing is FAA or CAA certifiers can not conjure up 50 knot crosswinds to test an aircraft. They demonstrate the aircraft to the maximum crosswinds they can find and then certify that as a demonstrated limit.

Bring all your protypes to Wellington in October and you could certify double the demonstrated limits.

Hey Centaurus I object to the unnecessary personal insult in your post. My recollections of the facts are perfectly accurate. Your personal attack on me is a cheap shot.

I take some pride in the landing which I performed. I did that landing well. I touched down very gently and properly aligned to the centreline. I did not bend or overstress the airframe. The CFI had implicit faith in me and was using me to demionstrate technique to another student who was having difficulties. Unlike most here, I don't sit and speculate about crosswind landings outside my personal experience.

I was only an SPL at the time. I turned up at the airport for a flying lesson that day not expecting the booked session to proceed. Airlines had stopped flying anything smaller than 737s that day, so i expected my 8am flying lesson to be cancelled. I couldn't reach the CFI by phone so i decided to drive to the airport. My CFI at the time and I will not name him because he is the most amazing pilot I have ever known, was then also an ATPL Captain flying F.27s.

I think you'll find Centaurus that when the runway is 16 and winds are 240 gusting to 55 knots there is little difference between component and actual crosswind.

I think if you had some common decency you'd publicly withdraw that walter mitty comment and apologise.

[c100driver]

Whilst Wellington airport only sees 733s land in 50-60 knot crosswinds a few days per year, I can say I have had a ringside seat on the Ramp to many hairy landings and these appear de riguer at WLG. I suspect there is a lot of commercial pressure on these guys that if the airport company does not close the airport due to high winds (which it rarely does) then the onus is on pilots to defy their employer.

As a lowly B737 kiwi pilot with 14 years experience into and out of Wellington ON the B737 alone. I have never seen a 50 to 60 knot cross wind in Wellington. Though it is common to have 50 to 60 knots, once over 45 knots it is usually straight up and down the track.

Our company limit IS: 29 Knots Dry runway B737-200 31 Knots Dry B737-300. 60 Knots from any direction is our company limit, but mainly due to ground handling issues; i.e. the airbridges cannot drive against the wind and move too much against the aircraft.

Boeing do not have a max cross wind limit, they have demonstrated each type to a high component and the the operator can decide. "Boeing Airliner" magazine had a table of the max cross wind they has demostrated for each type some years ago. The B737 figure was 45 knots.

The video you see of the B777 and B747SP comes from a Boeing Symposium in I think 2001. They do test the aircraft in a "no correction" cross wind landing. The B733 FCTM recomends 20 Knots max in the DRY for a "no correction" landing.

Now back to the thread; On the non FBW boeings I have flown if you dont hold the controls to stop the wing from rising it WILL roll quite spectaularly once airborne, espically the B732

[Capn Bloggs]

I'm with Centaurus. Anybody who tries to land a Cheetah in 45-55kts of crosswind is a hazard to themselves and their unsuspecting passengers and shouldn't have a licence.

Kiwiguy, so you honestly believe that Gulfstream couldn't find a crosswind of more than 11 kts to "demonstrate" it in? :{

[Kiwiguy]

At Wellington when the winds are too strong as happened just a couple of weeks ago the aircraft use airbridges on the lee side of the piers. I worked for Air NZ for several years and then as a caterer. I have had a ringside seat to many hairy landings at WLG.

Last October I saw a 733 wheelbarrow in exceptionally gusty conditions and in July last year saw a Qantas hydroplane sideways down the runway on 16. These incidents never turned up in CAA incident reports either. The captain was very red faced when I stepped aboard at gate 23.

The item I mentioned to Centaurus was from the archives here:

http://http://www.pprune.org/forums/archive/index.php/t-226895.html

and that item talked of Boeing's FTCM with apologies if I have misquoted any of it. It seems I did.

Incidentally the youtube clip above of a Boeing 777 landing in 50 knot crosswinds was piloted by John Cashman. I have read an account by a test engineer aboard who mentioned that the B777 has got a facility to swivel the main gear slightly, only intended for ground manouvering, but the engineer noted that pilots often mis-use the facility to crab the main wheels a la B-52 style prior to crosswind landings.

The A340-600 was tested landing in 45 knot crosswinds at Keflavik on 27 October 2004. The A380 was also tested landing in 50 knot crosswinds at Keflavik on 10 November 2006. These aircraft are capable of such things.

I touched down as smoth as silk. The Groundspeed almost matched the airspeed. I have seen harier landings by ATPLs with a planeload of passengers, by people who call themselves professionals.

[duece19]

I worked for Air NZ for several years and then as a caterer.

I touched down as smoth as silk. The Groundspeed almost matched the airspeed. I have seen harier landings by ATPLs with a planeload of passengers, by people who call themselves professionals.

Erm, Im not sure if I just read what I think I did. As a caterer Im sure you have genuine knowledge of landing airliners in crosswinds and as you seem to be superior to Gulfstreams flighttestdepartment I suggest that you immediatly apply for a position at ANZ and their traning department to teach crosswindtechniques.

You also state the "these aircraft are capable of such things" which is quite clearly indicated by the filmclips provided by previous posters. It is however not always prudent to fly an aircraft to its limits and I must say I have my doubts about ANZ pilots making landings in 60kts crosswind. Not that I have ever flown in to WLG myself but I do regularly land in strong (I guess its just a breeze to you) winds. At gusty winds up to 40 kts I dont really feel like trying another 20 across the runway but then again I aint a caterer.


Nah mate, I think you are talkin a wee bit rubbish here.

Back on the topic tho:

I dont fly the tripple, but the bobby version but I our FCTMs is pretty much similar on the xwind takeoff chapters.

I read a memo from Boeing a while back about applying intowind aileron during takeoff and if I remeber clearly it stated "that its easy to overapply intowind aileron during takeoff roll and thus causing spoiler deflection with a degredation in performance as a result" The memo further went on to state that the Boeing recommended procedure would be changed to "apply no intowind aileron during take off roll but do apply slight upwind aileron once rotation is started and maintain until mainwheels are airborne."

I probably didnt get the wording correct on that one but I believe that was the context of the bulletin.

Would anyone happen to know where I could find that bulletin again?

Duece

[galaxy flyer]

It should be obvious-professional pilot experience, training and company policy and regulations are irrelevant in the presence of the catering staff. I can't wait until my boss, who already thinks we are worthless primadonnas, hear what can be accomplished by the ground staff. 60 knot crosswinds would make some of those Kai Tek landings look like child's play.

I do salute those Boeing landings--anyone with flagging belief in the structures engineers should be reassured.

GF

[duece19]

I touched down as smoth as silk. The Groundspeed almost matched the airspeed.


It normally does in a crosswind!
:ugh:

[Jimmy The Big Greek]

one last question. This technique with not de-crabbing, is it a 777 thingy or is it valid for most jets.

[FullWings]

Incidentally the youtube clip above of a Boeing 777 landing in 50 knot crosswinds was piloted by John Cashman. I have read an account by a test engineer aboard who mentioned that the B777 has got a facility to swivel the main gear slightly, only intended for ground manouvering, but the engineer noted that pilots often mis-use the facility to crab the main wheels a la B-52 style prior to crosswind landings.
The 777 has no means of altering the angle of the main gear. What it does have is limited motion in the rear bogies to alleviate tyre scrub during tight cornering. This locks out when the aircraft straightens up. If you tried to land with this system activated (no way I know of doing that without major interference with the flight control systems) the results would be rather unpredictable and pretty dangerous, IMHO. If the main gear steering does not lock/comes unlocked during the takeoff roll, it will generate a config. warning leading to an RTO.
one last question. This technique with not de-crabbing, is it a 777 thingy or is it valid for most jets.
The videos linked to on this thread are mostly of test/certification flying by a manufacturer. I'm pretty sure that Boeing design their aircraft to be landed with no crosswind correction up to the limiting value. This doesn't mean that it is a) any good for the fatigue life of the gear/tyres/airframe b) comfortable to those on board or c) regularly practiced outside of test flying. There are situations where you might consider leaving the drift on (icy/slippery runways) and at the back of your mind you know that if you don't "de-crab" on a dry runway the aircraft should survive. Most pilots would attempt some form of correction before touchdown, however. The autopilot certainly does!

[slamer.]

My B777 instructor told me not to bank into wind during strong cross wind takeoff, because it will induce roll spoilers to extend. But I still think that we must give a little bank into wind to keep wing level for high swept back wing aircraft. My instuctor told me that to bank into wind is the thing of the past. Any comments.


Back to the begining.

Reading the above replies, it appears only a couple of you have actually flown an aircraft, let alone a heavy jet. If Aileron is not required with a decent crosswind (a relative thing & probably the real issue here) try it some time..... see what happens !!!!!...... Bungfai do you work for SQ ??

PS: Kiwiguy has got a little out of his depth, maybe the sharks could stop nipping his feet.

[Bungfai]

My B777 max cross wind limit company dry 30 wet 25. And some FI are trying to change to about 45 demonstration speed. But it will require crab landing technique avoiding engine touching the ground. What are your limits?

[bookworm]

The 737 is limited to 19 knots crosswind with minimal flaps and 23 knot crosswinds with 40 degrees flap. The limit applies to aircraft which are not de-crabbed. The limit is set not by the aerodynamic limit of the aircraft but rather by the strength of the undercarriage to resist hitting the runway sideways.

If the aircraft is de-crabbed to align with the runway in the flare then the risk is removed and theoretically if you use proper technique there is no limit.

I landed a Gulfstream Cheetah at Wellington's runway 16 in 45 knot winds gusting 55 knots from 240 degrees once. The crosswind limit on a Cheetah was 11 knots, but if you land properly it will handle that. The limit is on the undercarriage strength and not aerodynamic factors.

...The inference I took however was that if you de-crab in effect limit is not an issue. My humble opinion. Anyway you can take it from my equally humble efforts as a test pilot that this aeroplane (Cheetah) handles a damn sight more than the placarded limit.:8

...
That is, the crosswind limits on most aircraft are only the demonstrated limits and not the actual aerodynamic limits. Thing is FAA or CAA certifiers can not conjure up 50 knot crosswinds to test an aircraft. They demonstrate the aircraft to the maximum crosswinds they can find and then certify that as a demonstrated limit.

If you read the document you quoted carefully, you'll see that the terminology is maximum demonstrated crosswind component. This is not a limit and should not be considered limiting -- it would also be unusual to see it "placarded".

It is not set by "the strength of the undercarriage to resist hitting the runway sideways". Certification requires at least a certain minimum value to be demonstrated, and some manufacturers stop there. For light aircraft the value is 20% of the stall speed in landing configuration, which probably explains the 11 knots for the Cheetah.

There are both theoretical and practical limits on crosswind landing capability. For example if "the aircraft is de-crabbed to align with the runway in the flare" then the maximum achievable yaw rate will contribute to a limit.

[bookworm]

My B777 instructor told me not to bank into wind during strong cross wind takeoff, because it will induce roll spoilers to extend. But I still think that we must give a little bank into wind to keep wing level for high swept back wing aircraft. My instuctor told me that to bank into wind is the thing of the past. Any comments.

The critical factor is the lift generated in ground attitude just before rotation. If the aircraft is almost ready to lift its own weight, the rolling moment from the sideslip caused by the crosswind will lift the wing and aileron must be used to counteract this. Even if the wing doesn't lift, the different weights on left and right gear can make it hard to track the centreline.

I would imagine that the B777 needs a significant pitch rotation to get it to fly, thus the lift generated in ground attitude just before rotation may not be sufficient to cause directional issues without aileron input, even in strong crosswinds. For aircraft that "fly themselves off" at rotation, into-wind aileron is required.

[Bungfai]

Thank you so much, I have learnt lots of things.

[Miserlou]

I think some people are missing the wind-up merchant here.

Kiwiguy's statements about his Cheetah experience are plain bar talk. There, at least, people might believe him if it is late enough.

I have found most 'demonstrated crosswind' figures to be fairly realistic; most definitely conservative but not far off. But I suggest landing with 4-5 times the max demonstrated crosswind value is either stupid or reckless, possibly both.

Then there is the bit about the CFI being present. So that he could show a student how it should be done. Doesn't that ring strange to any one else?

Next time, get it on video:

[Loose rivets]

bungfai,
this is what my copy of B777 FCTM says. i took the liberty of underlining the relevant sentence.
http://i123.photobucket.com/albums/o310/palmiator/fctm.jpg


Thank heavens! I thought I was entering the twilight zone.

The funny thing is, that when I was trying to think how I would do it, it was not really clear. It's just sort of automatic, but the page reads just as I would have expected.



I spent some time flying in conditions that often far exceeded the normal limits, there were no civilian passengers and it was certainly out of the CAA's remit, but I had the advantage of first flying with guys that had done it for years.

The point is, that people that have to routinely do this kind of flying seem to be able to do it without the slightest increase in stresses on the aircraft. In fact, compared to the test-flying shots, most of the landings were non events.

I cannot pontificate about FBW, but certainly heavy turbo prop and the early swept wing jet transports were all perfectly controllable way over book limits. It was just a question of being allowed to enter that territory. Clearly you can't fool around with hundreds of $m worth of kit, so you can never get confident about the more extreme conditions. But if you were allowed to, you would do it with ease...after a few interesting moments.


Despite all this, the worst ever single gust I ever experienced was at Leeds. 60kts on the rear quarter -- just as we were touching down. The air-stairs bowled across the pan and the young lady was blown over and had to be replaced by a (this is so non-PC) by a man.

[FullWings]

My B777 max cross wind limit company dry 30 wet 25. And some FI are trying to change to about 45 demonstration speed. But it will require crab landing technique avoiding engine touching the ground. What are your limits?
Ours are 40/40 and that includes the autopilot. I can't say with absolute confidence that you won't contact the ground "wing down" at 45kts across as I've only tried it in the sim but I'm pretty sure this is the case. Boeing will tell you for sure.

If faced with a landing "in extremis" at or above the x-wind maximum for the type I was flying, I would use as much "wing down" as I thought was reasonable and let the gear take the rest of the leftover crab. I wouldn't revert to a "crab only" touchdown...