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bank into wind during strong cross wind takeoff

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bank into wind during strong cross wind takeoff

Old 19th Nov 2006, 13:59
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bank into wind during strong cross wind takeoff

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.
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Old 19th Nov 2006, 18:09
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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?
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Old 20th Nov 2006, 22:13
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Thanks, my manual doesn't say any thing about it. Any of you guys with B777 can give me some ideas ?
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Old 20th Nov 2006, 23:03
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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
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Old 21st Nov 2006, 00:36
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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!
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Old 21st Nov 2006, 01:23
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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...).
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Old 21st Nov 2006, 01:36
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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.
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Old 21st Nov 2006, 05:57
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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.
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Old 21st Nov 2006, 06:26
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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.

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Old 21st Nov 2006, 06:53
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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.
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Old 21st Nov 2006, 07:31
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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.
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Old 21st Nov 2006, 07:43
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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.
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Old 21st Nov 2006, 07:53
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I did not know this and I must say that I dont like the idea with not de-crabbing.
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Old 21st Nov 2006, 08:59
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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.
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Old 21st Nov 2006, 09:20
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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

(These links should work now)

Last edited by Kiwiguy; 21st Nov 2006 at 20:26. Reason: fixing hyperlinks
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Old 21st Nov 2006, 10:10
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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!
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Old 21st Nov 2006, 13:31
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bungfai,
this is what my copy of B777 FCTM says. i took the liberty of underlining the relevant sentence.
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Old 21st Nov 2006, 14:57
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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.

Last edited by Centaurus; 21st Nov 2006 at 15:09.
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Old 21st Nov 2006, 20:07
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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.

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_su...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.

Last edited by Kiwiguy; 21st Nov 2006 at 20:57.
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Old 21st Nov 2006, 21:16
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Originally Posted by Kiwiguy
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

Last edited by c100driver; 21st Nov 2006 at 21:42. Reason: thread creep
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