Takeoff with light quartering tailwind

[mfclearner]

What should be aileron position if you are taking off in light quareting tailwind? What i learned in CPL Days was...
for taxiing in light quartering tailwind (say from left) hold control wheel to the right so that my left ailerons are down and right ailerons are up. Does same thing hold good for takeoff also?

[5LY]

No. Into wind for t/o.

[iFly738]

always into the wind.

Don't know what airplane you are flying, but beware of the fact that if you displace the yoke to far into the wind -> your spoilers will also come up -> causing more drag.

[mfclearner]

Referring to this webpage http://freepilotinfo.********.com/2010/01/remembering-correct-x-wind-taxi.html shows POH diagram for taxiing with tailwind. It says left quartering tailwind left aileron down. So why would it be different for takeoff?

If it is b737 what will be aileron position with light quartering tailwind?
Note: just insert word b-l-o-g-s-p-o-t in above weblink without dashes

[STBYRUD]

Sure, always into the wind, why would it be different?

[WallyWumpus]

Once the take off run is commenced then you do not have a tailwind in any real sense. The ground speed will be higher than your airspeed, but there is not wind coming from behind, and over, the tail and wings.

Control displaced when taxiing light aircraft can be "reversed", because at that stage there may be wind coming from behind, but this is quite different.

Wally.

[framer]

Thats a good way of explaining it Wally :)


Don't know what airplane you are flying, but beware of the fact that if you displace the yoke to far into the wind -> your spoilers will also come up -> causing more drag.

True ifly, but how far is 'too far' ? If you are looking at the aileron trim markings on the yoke in front of you, how many before the spoilers rise?

[STBYRUD]

Went through the trouble of checking the AMM about this a while back for the 737, If I remember correctly the spoilers start to come up at 1.6 units on the yoke. Still - this is not a reason to limit aileron inputs if they are required...

[framer]

Begin the takeoff roll with the control wheel approximately centered. Throughout
the takeoff roll, gradually increase control wheel displacement into the wind only
enough to maintain approximately wings level.
Excessive control wheel displacement during rotation and liftoff increases
spoiler deployment. As spoiler deployment increases, drag increases and
lift is reduced which results in reduced tail clearance, a longer takeoff roll,
and slower aircraft acceleration.


This is from a 737 FCTM. Two things stand out to me. 1/Many pilots I fly with don't start the roll with the control wheel approximately centered and increase it as it is required. And 2/ What is "excessive" control wheel displacement?

[JammedStab]

This is from a 737 FCTM. Two things stand out to me. 1/Many pilots I fly with don't start the roll with the control wheel approximately centered and increase it as it is required. And 2/ What is "excessive" control wheel displacement?

Can you tell me which model 737 FTCM you are quoting from.

Thanks

[framer]

From an 800 model.

[MarkerInbound]

In the 727, the spoilers come up after the yoke is rotated 10 degrees. In the 747 for dummies manual I've got with me, it doesn't give a number, it just says the ailerons and spoilers work together for roll control. Hey, if it's not in the book, they can't ask about it on the oral.

In most transport airplanes you are limited to a 10 knot tailwind. You're going to change that around to a headwind before the power is even half way set.

[bubbers44]

That was the procedure taught in J3 cubs and light aircraft, not airliners. They don't get flipped over by gusts like the light stuff unless you are really stupid.

[Crashdriver]

Throughout the takeoff roll, gradually increase control wheel displacement into the wind only enough to maintain approximately wings level.

Why are you increasing control wheel displacement as airspeed increases? If this theory were to hold true than you would have a large amount of aileron deflection as they become effective, leading to worse problems than a tailwind <10 kts.

You should start with it deflected and return to neutral as the airspeed increases so that you leave the runway wings level.

[framer]

In the 727, the spoilers come up after the yoke is rotated 10 degrees.
I haven't flown the 727, does it have markings indicating when you've reached 10 degrees rotation?

[framer]

You should start with it deflected and return to neutral as the airspeed increases so that you leave the runway wings level.

Thats not what boeing say. I see quite a few pilots starting with it already deflected and working backwards to somewhere thats hopefully right. If you do it like the book says it works nicely, you never end up with too much aileron. Do you ease off the aileron as the airspeed increases and then during rotation change direction and increase the aileron input again in order to maintain the wings level during rotation?

[Crashdriver]

Framer
I think you may have mis-read the book or are reading from the landing section where you increase aileron deflection as the speed decreases and the ailerons become less effective.

I find it hard to believe that Boeing would publish something like this. If you start at neutral and work into the wind as the airspeed increases you're trying to roll the airplane while it's still on the ground. This puts extra stresses on the landing gear and really stresses that work their way back to the wing root. Not to mention differential drag on the main landing gear causing a yaw in the direction of aileron deflection. So that takes care of the problems on the ground.

Now for the problems in the air. The ailerons work by changing the lift on the individual wings. Aileron down, increased angle of attack, more lift and vice versa. So as you get closer to Vr one wing will be making the lift required for rotation before the other. You can see where this is going. Now you have one wing flying and the other one...well...not. And since both wings are connected, with asymmetrical lift one goes up, the other goes down. And it's not long till the tip of the wing meets concrete and the insurance rate begins to climb.

The procedure for takeoff (this could be different in the bigger jets with roll spoilers and all that stuff, the biggest thing I've ever flown is a King Air) is to start with the ailerons deflected fully into the crosswind, whether it's a headwind, or tailwind, that doesn't matter, because like someone else said the tailwind is gone by the time the engine is halfway to takeoff power. As the airspeed increases you'll feel the control forces increase (hydraulic controls too? I think, dunno, never flown 'em) so you slowly "give in" to the suggestion the airplane is giving you and begin to return the control wheel to neutral. The goal should be to hit neutral just before rotation speed, pull the airplane off the runway, and adjust bank angle as appropriate.

[framer]

My goodness you're authoritive for someone who has never flown the aircraft you are giving advice on.

I think you may have mis-read the book or are reading from the landing section where you increase aileron deflection as the speed decreases and the ailerons become less effective.

I find it hard to believe that Boeing would publish something like this.
Different machinary, different techniques required. Boeing did publish that,it is a direct cut and paste from the latest update :)

The goal should be to hit neutral just before rotation speed, pull the airplane off the runway, and adjust bank angle as appropriate. That aint gunna be pretty in a 737.

[JammedStab]

Interesting. From the Flight Crew Training Manual for the 737-200 dated in 2005, it says simply "maintain wings level during the takeoff roll by applying control wheel displacement into the wind".

[Capt Claret]

An old instructor, ex RAAF - eccentric but a gifted instructor, taught that the ailerons are for roll control.

Therefore, if barrelling down the runway and the wind is not sufficient to cause any roll, leave ailerons neutral. If the wind is causing some roll (there won't be much because the darned thing's on the ground) only use enough aileron to keep wings level (ie, use the natural horizon).

Simple. :ok:

[MarkerInbound]

I haven't flown the 727, does it have markings indicating when you've reached 10 degrees rotation?

Yes it does.

[framer]

That would be handy. I wonder why they did it for the 727 and not the 737?

[STBYRUD]

As I said, thats approximately 1.6 units as indicated on the yoke on the 737 if memory serves me right.

[Crashdriver]

Different machinary, different techniques required. Boeing did publish that,it is a direct cut and paste from the latest update

When it comes right down to it, no. All airplanes fly the same, from a J3 to an A380. Pull back the houses get smaller, push forward they get bigger. (for the Airbus I guess I apparently have to make the disclaimer that it's in it's "normal flight mode" or whatever the technical term is for it.)

My goodness you're authoritive for someone who has never flown the aircraft you are giving advice on.

No I'm using common sense and thinking about what would happen if you lift off the runway with full aileron deflection.

[NARVAL]

Thank you for all those insights.
In fact, I would avoid taking off with a tailwind, but if it cannot be avoided, then, as Captain Claret wisely said, ailerons are for roll control!
You use the tiller (is that right? I mean using the nose wheels orientation) , at the start of the take off roll, then remember that what is important is acceleration, to V1 and Vr...putting weight on one main landing gear by using ailerons is not, I beleive, a good idea, especially as the wind is "light", by the topic"s description. Use slight rudder inputs afterwards to keep the airplane centered, and rotate with the ailerons still neutral. I am always surprised to find that now, everything needs to be written and explained, when in fact, there are so many different conditions which cannot be all adressed. It is, in fact, state of the art piloting...I learnt by looking at (and admiring...) how the old hands did it, then later shared it with the younger ones...No need to cut entire forests to write that in the SOPs...

[Castle Don]

framer, your are correct mate.

Same general wording as my 747-400 manual.

They don't want you barreling down the drag strip with the spoilers up on one wing, eating up tarmac, reducing lift, reducing tailstrike margin...etc etc.... when ultimately, only a smidgen of into-wind yoke may be needed.

Maybe full aileron in a small/light aircraft without spoilers would be appropriate. As has been said...different methods for different machines.

[JammedStab]

When it comes right down to it, no. All airplanes fly the same, from a J3 to an A380.

One should not be misled by this quote. There can be significantly different ways of flying different aircraft. For example. from what I have been told, using control wheel after an engine failure in an MU2 can be very dangerous.

Bottom line....When it comes right down to it, not all airplanes fly the same.

[framer]

Crashdriver
When it comes right down to it, no. All airplanes fly the same, from a J3 to an A380.
Someone tell you that in the hangar Crashdriver? Or the result of years of research flying many types in the exact same fashion? It sounds quite good,gives you an air of experience and wisdom, but it's not true.

If you started your roll on a 737 with full aileron and reduced it so that you rotated with ailerons neutral in a stiff crosswind, it would be an almighty cock-up. Simple as that really. If you did it in your B200 it might work pretty well......it's starting to look like All airplanes fly the same is just a convenient saying.
If anyone reads this thread for advice I'd suggest they be rather judicious about who they take it from, better yet, follow the manufacturers guidelines.
STBYRUD As I said, thats approximately 1.6 units as indicated on the yoke on the 737 if memory serves me right.
I'd be really interested in nailing that figure down. Have you still got access to the AMM?

[Crashdriver]

Someone tell you that in the hangar Crashdriver?

No actually it was a university professor in aeronautical physics. And the physics of your explanation is what I have trouble believing. Before I spend the next 3 hours flaming, I will leave it at that and leave you to your own devices, since an academic conversation cannot be completed here.

[framer]

Ahhh come on Crashdriver, we were on the verge of learning something then. Lets get to the bottome of it :ok:

No actually it was a university professor in aeronautical physics.

He should get in touch with Boeing and tell them their FCTM is incorrect and that the same crosswind departure technique as the J3 Cub will suffice.
I will leave it at that and leave you to your own devices, since an academic conversation cannot be completed here.
My favourite part of the acedemic conversation thus far has been
Pull back the houses get smaller, push forward they get bigger.

[STBYRUD]

framer: Tell you what, I will do some empirical testing during the next flight control check, aided by either the ACMS or the sys page if the bird has the flight control display - don't have access to the AMM at the moment unfortunately :(

[framer]

Good idea STBYRUD, I look forward to the results.

[john_tullamarine]

All airplanes fly the same, from a J3 to an A380

I think one might choose a Type a little more modern than the Cub. However, with that caveat, it is not unreasonable to suggest that Types certificated to modern Standards - FAR23/25, for instance, generally will fly in reasonably predictable and similar manner.

That is not to suggest that different Types won't have specific differences, of course.

I suspect that the original statement would have been somewhat along such lines. Certainly, I have heard much the same comment from a variety of competent folk over the years.

[JammedStab]

Back to the crosswind stuff. Seeing as most aircraft seem to use a technique of reducing aileron into wind as airpeed increases on the takeoff roll, can we get any confirmation on this idea that Boeing is suggesting the opposite.

[framer]

This is my take on it and I'm happy to be corrected by folk more knowledgable/ more experienced than me;

When you are rolling along the runway at speeds where the rudder is effective during a crosswind departure, you want to control your direction with your rudder while preventing the upwind wing from creating more lift than the downwind wing. If you end up in the situation where the aileron input is creating a drag towards the upwind side of the runway, then the opposite rudder you will need isn't to counter the wind, it's for the aileron/spoilers.
I have a feeling this happens quite a bit.
I think Boeings technique is designed to prevent excessive control inputs.

[framer]

PS Jammed Stab,
I don't think Boeing are suggesting that the inputs continue as the airspeed increases. I'l paste below so it's easy to reference;

Throughout
the takeoff roll, gradually increase control wheel displacement into the wind only
enough to maintain approximately wings level.

So what happens is that aileron goes in as required until the point is reached where it is sufficient and then it is held. (this is normally only a very small input) My experience is that as the airspeed increases and slightly less rudder is needed then the aileron is reduced a fraction with the rudder..... almost like they are connected really. Until rotation of course when the into wind aileron is pretty much doubled or trippled in order to keep the wings level.

[misd-agin]

All airplans fly the same? To some degree yes, to some degree no.

Anyone think a swept wing, hard wing fighter would react differently to a rudder input at high AOA, like landing, than a Piper Cub?

Ailerons are neutral and only enough input is needed to keep the wings level during takeoff roll.

In strong crosswinds the plane typically doesn't 'lean' until it's moving fairly quickly so a small, or perhaps moderate, amount of roll input might be needed but that will gradually be reduced as speed, and thereby roll effectiveness, increases.

[PPRuNeUser0190]

Hello guys,

I was briefed during my type rating that the Boeing technique for crosswind take-off has to do with the swept wing.

Not 100% sure about this but I think it was this.
The wing which is on the crosswind side gets air over the wings at an higher angle (closer to perpendicular) than the wing on the other side (closer to parallel). So the wing on the crosswind side is creating more lift and this needs to be countered by applying aileron into the wind. As speed increases the effects gets bigger, so more aileron needed.

[JammedStab]

That would be handy. I wonder why they did it for the 727 and not the 737?

The 737-200 has markings on the yoke to show degrees of control wheel displacement.

[misd-agin]

Boeing has stated what they expect a pilot in their aircraft to do. They do not say "keep the wings level". They say "approximately level."

They are more concerned with drag by excess control wheel displacement vs. not being perfectly level.

Using control wheel inputs in a jetliner that are appropriate for light aircraft flying shows a failure to understand what you're doing with the control wheel(drag) vs. how jet performance is calculated.

[framer]

Hey Jammedstab, I have never flown the -200, but the 3 4 and 800's have 'aileron trim units' on the yoke. Are you sure you are not getting mixed up with these markings?

[STBYRUD]

Seems I was correct about 1.6 units - thats when the flight spoilers start to show a deflection, just tried it out today (well, between 1.5 and 2, its a very small difference anyway)...

[framer]

Brilliant stbyrud, thanks for that. was that on an -800?

[captjns]

In all the Boeings from the 727 up to the Whale, the takeoff run is started with the wheel neutral. As you know a plane is nothing but a big weather vane. If the wind hits the right side of the vertical stabilizer the nose will want to go the right. Thus you need left rudder to offset the effects of the crosswind. The amount of left rudder input will decrease as the speed increase and the airflow over the vertical stabilizer takes effect. At the point of rotation, not being a Microsoft or simulator pilot, attention is outside the cockpit and not at the control wheel.

That said if I maintain left rudder input with the wheel neutral at rotation the aircraft will veer left and eventually roll left too. Thus you need to input right aileron. How much? Like I said, not being a simulator or Microsoft pilot I use sufficient aileron to maintain a wings level constant heading at the point of lift off. After liftoff then the aircraft is deslipped by neutralizing the controls and finding the proper crab angle to maintain desired track. Nothing scientific about a crosswind takeoff. Works the same way in Cubs, Stearmans, Pitts, Extras, Cessnas, Beechcraft, Commanders. I will say the only aircraft which is a bit twitchy on crosswind takeoffs was the good old reliable Aircoupe... no rudder pedals:eek:!.

[JammedStab]

Hey Jammedstab, I have never flown the -200, but the 3 4 and 800's have 'aileron trim units' on the yoke. Are you sure you are not getting mixed up with these markings?

The best I can do is get you to click onto this picture...

Photos: Boeing 737-201 Aircraft Pictures | Airliners.net (http://www.airliners.net/photo/USAir/Boeing-737-201/1275371/L/&sid=759c7f0228214b516cf896b666599443)

It is a bit difficult to see but if you look closely at the top of the control columns, you will see that it says "Control Wheel Degrees" and the markings go from 0 in the middle to 50 on either side.

[framer]

Jammedstab, thanks very much for that. Sorry to doubt. I wonder why they changed it to 'aileron trim units' for the subsequent models?

[JammedStab]

Boeing has stated what they expect a pilot in their aircraft to do. They do not say "keep the wings level". They say "approximately level."




Actually 737-200 FCTM dated April 30 2005 on page 3.11 says..." Maintain wings level during the takeoff roll by applying control wheel displacement into wind"

Not sure where you got your info from.

[framer]

Maybe Boeing advise different techniques for longer aircraft?

[misd-agin]

Jammedstab - that was a quote from post #9's Boeing manual.

Checked two Boeing manuals I have and they say "limit control wheel input to that required to keep the wings level."

[JammedStab]

In all the Boeings from the 727 up to the Whale, the takeoff run is started with the wheel neutral.

I disagree. On the 727, I used to initiate the takeoff roll with aileron into any significant(my estimation) wind and maintained aileron into wind throughout the roll(although it would back off somewhat as speed increased). Aileron was maintained into wind throughout the rotation as I didn't want a wing to drop during the rotation when they are closer to the ground. Worked well.

[captjns]

You are entitled to your opinion JammedStab

After some 20000 of PIC jet time with 5000 plus hours of Captaining the finest jet off the Boeing assembly line, the good old reliable 727 that is, I never had a near excursion or overrun on takeoff using my technique. The FAA was satisfied as well as I trained some of their folks too. At the end of the day, I guess what ever works...

My point is that one's attention during the takeoff roll should be out the window and not at the control column and provide the appropriate control input accomplish a successful wings level takeoff.

[misd-agin]

Crosswind takeoffs - at liftoff the cross control should be approximately the same as if you'd just touched down on landing.

If X crosswind controls = zero drift on touchdown that's the expected, and desired, performance on liftoff.

It's a blend of technique and mechanical inputs. Boeing talks about 'smoothly'. :ok::D Mechanically? Rudder input will be greater than required aileron input(only enough to maintain wings level) while accelerating. At rotation more aileron will be require. How much? Think of your crosswind landing control inputs - if X rudder than give X aileron a try and make small(smooth) adjustments as you lift off and start your initial climb.

Smooth input as necessary, maybe a slight increase immediately prior to Vr to achieve correct cross control for zero sideload on liftoff, reduce rudder first to allow nose to turn into wind (equal to crosswind) to maintain runway track, and level wings on correct heading.

It's nice to see done correctly. If you've never flown with the other pilot before you'll have some insight to their ability by 100' on departure if there's a stiff crosswind. Hopefully it's :D and not :rolleyes:.

(the slight increase in aileron is my opinion and no comment is made about it in Boeing statements)

[JammedStab]

You are entitled to your opinion JammedStab

After some 20000 of PIC jet time with 5000 plus hours of Captaining the finest jet off the Boeing assembly line, the good old reliable 727 that is, I never had a near excursion or overrun on takeoff using my technique. The FAA was satisfied as well as I trained some of their folks too. At the end of the day, I guess what ever works...

My point is that one's attention during the takeoff roll should be out the window and not at the control column and provide the appropriate control input accomplish a successful wings level takeoff.

While I am sure your technique works based on your extensive experience, this is to show where I got my opinion about not initially maintaining neutral aileron in a crosswind takeoff...

http://i1091.photobucket.com/albums/i399/54H60/727Xwind.png

[framer]

So all we know really is that Boeing recommended a different technique for the 727 than they are currently recommending for the 737 yeah?

[JammedStab]

So all we know really is that Boeing recommended a different technique for the 727 than they are currently recommending for the 737 yeah?

Are not posts #47 and #53 almost the same with the newer plane being perhaps a little less descriptive. Maybe you mean the 300 and greater series.

[framer]

You're right I do Jammedstab. Ta.
With that in mind, maybe it's not so much a 'type' thing as a time thing. Maybe around 2006 Boeing decided to change technique so that the roll started with the yoke centered and aileron was introduced to keep wings "approximately level" during the roll?

[Rick777]

Boeing changes their manuals at least once a year plus different operators may have different wording and techniques in their manuals. At the start of takeoff roll there is no airflow over the control surfaces so it doesn't matter where the controls are. Once you start to roll you steer with the rudder and keep the wings level with the ailerons. If you maintain runway center line and lift off with wings level you did it right. After becoming airborne you will be in a slip. Gradually take out the cross controls and fly whatever heading or course you need. I don't know whether the starting position for small airplanes is important, but after you get rolling they all work the same.

[GlueBall]

I don't pre set nor do I allow my F/O to pre set ailerons.

In the B747 training manual [published by Boeing] it says:

"To prevent spoiler drag early in takeoff roll, do not preposition aileron into the wind until wing roll is noted."

[Pub User]

The Boeing 737 (300-900) FCTM reference is quite a recent change, they are now on Revision 9, dated 30 June 2010.

Edition 7 had the 'old' guidance as follows (cut & pasted):
Maintain wings level during the takeoff roll by applying control wheel displacement into the wind. During rotation continue to apply control wheel in the displaced position to keep the wings level during liftoff.

This was replaced in Revision 8, 31 October 2008, by the guidance given earlier, which is still the same in Revision 9:

Begin the takeoff roll with the control wheel approximately centered. Throughout the takeoff roll, gradually increase control wheel displacement into the wind only enough to maintain approximately wings level.

This shows that techniques are constantly under revision, and referring to FCTMs dated 1985 is probably not the best way to keep your skills up to date. Likewise referring to other machine's training guidance is not wise.

As for the statement "all airplanes fly the same", that is clearly rubbish, although a university professor in aeronautical physics may put it that way, because the fundamentals of lift/drag/thrust/weight/bernoulli etc do not change. They may all fly by the same principles of physics, but their handling qualities can be vastly different.

[JammedStab]

This shows that techniques are constantly under revision, and referring to FCTMs dated 1985 is probably not the best way to keep your skills up to date. Likewise referring to other machine's training guidance is not wise.



It sure would be interesting to find out why the change was made. I suspect that there is a discussion prior to making such a change.

[captjns]

A lot of the post WWII Boeing manuals referred to takeoff and landing techniques from that era. Even to rotation techniques from the Dash 80 were incorporated into manuals up through the 80's which did not apply to better performing aircraft.

Rotating a fully loaded -900 with derated thrust to 24k at 3 degrees per second to 15 degrees nose with an OAT of 38 degrees will result in a tail strike.

FCTMs need to be updated to meet actual handling and performance for the the respective aircraft to which it applies rather than generalizations as they were in the 80's and even 90's for that matter.

[framer]

Rotating a fully loaded -900 with derated thrust to 24k at 3 degrees per second to 15 degrees nose with an OAT of 38 degrees will result in a tail strike.


I think this is what has driven it. The longer aircraft make it more critical.
When they decided to make longer and longer versions things like spoiler deflection became important so they have had a wee re-think.

[misd-agin]

Crosswind Landings during a storm at Düsseldorf B777,767,757 A330 Sturm Andrea, (watch in HD) - YouTube

Crosswind landings, and then takeoffs, at Dusseldorf.

Best takeoff, least amount of downwind drift on rotation, is a 767 at the 5:50 mark.

Condor A320 shows flight control inputs(zero) until rotation. A slight roll input to the right is obvious at rotation. Guten job, jungens!

Crosswind is approximately 30 knots with higher gusts. Control inputs for crosswind on takeoff, if any, were very slight. :D

[Yankee Whisky]

The description of the condition is "light ......" therefore, why bother
about aileron setting ? Once the relative tailwind component is overcome, the take-off will be like any other EXCEPT it will be a longer roll.

If it were a strong tailwind quartering component, I will invariably
elect to taxi to the other end of the RW and take off into a quartering headwind component.:O