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JammedStab
3rd Nov 2008, 03:27
I always wondered if holding lots of aileron into the wind did some potential harm because of spoiler actuation. I see that Boeing also recommends delaying rotation slightly in strong x-wind condition but I have never seen it written down anywhere. Is this what you have been doing in your Boeing or non-Boeing aircraft?

LAX04LA050 (http://www.ntsb.gov/ntsb/brief2.asp?ev_id=20031122X01939&ntsbno=LAX04LA050&akey=1)


LAX04LA050On November 14, 2003, about 1250 Pacific standard time, United Airlines Flight 805, a Boeing 747-422, N178UA, experienced a tail strike on rotation at San Francisco, California. United Airlines, Inc., was operating the airplane as a scheduled international passenger flight under the provisions of 14 CFR Part 121. The airline transport pilot licensed captain, 3 aircrew members, 17 flight attendants, and 335 passengers were not injured. The airplane sustained substantial damage. The flight was en route as a non-stop to Hong Kong, China. Visual meteorological conditions prevailed, and an instrument flight rules (IFR) flight plan had been filed.

The operator submitted a written report. The first officer was the Pilot Flying (PF), and the airplane departed on runway 10L. The winds were 180 at 16, gusting to 22 knots. The takeoff roll was normal, and the PF utilized control wheel input to correct for the crosswind. A few seconds after rotation, the PF noted the stick shaker annunciate, and responded by gently easing back pressure off the control yoke. The captain and a relief pilot felt a nose wheel vibration following the takeoff.

The air traffic control tower contacted the flight crew alerting them of a possible tail strike after observing smoke from the airplane at rotation. The crew returned to land at San Francisco. Evaluation of the damage resulted in structural repair to two structural members.

A National Transportation Safety Board specialist examined the solid state flight data recorder (FDR) and prepared a factual report. It included graphical plots of pertinent data. Boeing also evaluated the FDR data.

The data indicated that the takeoff occurred during variable wind conditions. The wind shifted resulting in a decreasing headwind, and an increasing crosswind, to an average 8-knot tailwind during rotation. During the takeoff roll, the data showed right control wheel inputs and left rudder pedal, suggesting that the winds had a crosswind component from the right. The maximum pitch rate was slightly higher than average, but within the normal expected variation. Boeing felt that this was a minor contributor to the tail strike. The PF used significant wheel input (35 degrees right wheel); this resulted in the right spoiler raising 12 degrees. Boeing pointed out that there was a loss of lift due to the use of spoilers. They also pointed out that rotating at a lower airspeed requires a higher angle of attack, and therefore, a higher pitch attitude to achieve liftoff. The combination of the tailwind gust and spoiler movement resulted in the airplane's pitch attitude exceeding 12.6 degrees, while the gear was still on the ground. This resulted in the aft body contact with the runway.

Boeing discussed a typical takeoff in gusty or strong crosswind conditions. They recommended maximum takeoff thrust, and to avoid rotation during a gust. Slightly delaying rotation would allow the airplane additional time to accelerate through the gust, and the greater airspeed would improve the tail clearance margin.

The FDR-recorded longitudinal control system parameters suggested a properly functioning system. The airplane motion was consistent with the control inputs and power settings.

The National Transportation Safety Board determines the probable cause(s) of this accident as follows:

a tail strike due to a combination of the wind shifting from a headwind to a tailwind during rotation, and the pilot's control inputs for the crosswind condition.

Meikleour
3rd Nov 2008, 10:16
If my memory is correct after 30 years I recall that the B707 used to have a performance decrement applied in strong crosswinds (15 kts + I think) which was to compensate for the spoiler drag.

On the modern FBW Airbus`s the technique is to centralise the ailerons at the point of rotation and indeed to avoid using excessive aileron into wind ie. enough to raise the spoilers, by restricting the sidestick input by use of the `cross` to a value where the spoilers are not deployed.

ex-rotaree
3rd Nov 2008, 10:42
From Boeing 737 Flight Crew Training Manual (Oct 31 2007 Revision)

Directional Control

.....Large control wheel inputs can have an adverse effect on directional control near V1(MCG) due to the additional drag of the extended spoilers.....

Rotation and Takeoff

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. The airplane is in a sideslip with crossed controls at this point. A slow, smooth recovery from this sideslip is accomplished after liftoff by slowly neutralizing the control wheel and rudder pedals.

Gusty Wind and Strong Crosswind Conditions

....Avoid rotation during a gust. If a gust is experienced near VR, as indicated by stagnant airspeed or rapid acceleration, momentarily delay rotation. This slight delay allows the airplane additional time to accelerate through the gust and the resulting additional airspeed improves the tail clearance margin. Do not rotate early or use a higher than normal rotation rate in an attempt to clear the ground and reduce the gust effect because this reduces tail clearance margins. Limit control wheel input to that required to keep the wings level. Use of excessive control wheel may cause spoilers to rise which has the effect of reducing tail clearance.....

It's easy, they tell me how they want it flown, I fly it that way, then they pay me;)

Rainboe
3rd Nov 2008, 12:05
This whole area is clouded with confusion! On the 747 in particular, there is a VERY strong tendency to lift the upwind wing in a crosswind take-off. Try leaving the control wheel centralised and you will have a surprise during the roll. I have seen a nasty scene develop during a strong crosswind take-off at LHR (right opposite our crew report centre) through a pilot not having any aileron on at all, and that was on lift off.

For the incident in question, I would have held at least 4 divisions aileron on throughout roll and rotation, as I have been taught all my career on several types, and allow it to bleed off as the aeroplane stabilised in the air as the drift started getting applied. I have to question again how much drag the barely extended spoilers (only on one side) actually give at any stage below 140 kts given that the rudder is also applied as well as the ailerons on both sides. The spoilers very slightly extended on one side give nothing more than a minute asymmetric effect These are the self same speedbrakes that even below 250kts actually apply very little drag even fully extended!

How about BelArgUS giving an opinion from a very experienced 747 man?

Port Strobe
3rd Nov 2008, 12:30
Wouldn't there be a larger deviation between estimated and actual induced drag caused by incorrect assumed masses for passengers and baggage on every flight than the short term increase in drag associated with spoiler drag on one wing on the 5% of days it's gusty across the runway and you happen to be working? As Rainboe said, these things are barely effective from 250kts and below on most medium/large jets, and control always come before performance so why try to get airborne risking a pod strike with the roll due to the crosswind? As ex-rotaree pointed out, they tell you to take it easy on rotation in these conditions and move the controls as required without over doing it, perhaps it was just an unfortunate incident where a few things were stacked against the PF in this case. I'm sure if we give it long enough somebody else will be getting criticised for not using enough into wind aileron during with t/o or landing and bending the jet.

411A
3rd Nov 2008, 12:42
If my memory is correct after 30 years I recall that the B707 used to have a performance decrement applied in strong crosswinds (15 kts + I think) which was to compensate for the spoiler drag.


Nothing wrong with your memory, quite correct, about the B707.
Adding large amounts of aileron early in the takeoff roll degrades takeoff performance, so add the aileron (for crosswinds) only as needed, and delay rotation slightly, for added control margin

Slightly extra speed in these situations, is your friend.
In fact, this (added speed) procedure is used for improved climb performance, where excess runway is available.
Pretty standard stuff with many Boeing (and Lockheed) jet aircraft.

Rainboe
3rd Nov 2008, 12:56
Adding large amounts of aileron early in the takeoff roll degrades takeoff performance, so add the aileron (for crosswinds) only as needed,
Never agreed with this! Early in teh take-off roll, is there absolutely any drag from aileron control or minor spoiler uplift? It only starts applying and being effective above 80-100kts. I was taught 'apply what you think is right at the beginning of the roll, and hold it there until it becomes effective. You then don't have to think about it during the roll when you are fighting with the rudder to maintain the centreline. Then feel for the wing lifting and keep it down, hold aileron on during rotate and start feeling for wing drop and control it as the aeroplane yaws and settles into drift.'

Magic technique that worked on the 747, 737 and 757. It works. The fact there was a stickshaker/tailstrike incident on this particular take-off leads me to say there were other factors present. No way should a medium crosswind have induced that. I would be more interested in examining speed, rotation rate and rotation angle reached. Not any nonsense about blaming aileron control during roll! (speaking from the POV of an 18 year 747 pilot from a fleet of 57 of them doing regular high weight flights, with no T/O tailstrikes!)

Phantom Driver
3rd Nov 2008, 18:34
Basic rule of thumb given to me by an old timer (possibly one of Rainboe's ex colleagues) when I converted to the 744; 10kts x-wind? Hold 1 unit (control wheel aileron trim indicator) of into-wind aileron; 20 kts-2 units etc. and that's right from the start of the takeoff roll. That, together with a smooth and slow(ish) rotation rate seems to work pretty well, followed by standard basic technique of centralising controls once airborne, as already pointed out.

Different case on landing in strong gusty x-winds when more aggressive work is needed to keep the wings level and avoid a pod strike (over 7 degrees roll in a typical extended flare will put you in that territory). I was surprised how eager that big wing is to start lifting when the winds blow.

fireflybob
4th Nov 2008, 00:50
Never agreed with this! Early in teh take-off roll, is there absolutely any drag from aileron control or minor spoiler uplift? It only starts applying and being effective above 80-100kts. I was taught 'apply what you think is right at the beginning of the roll, and hold it there until it becomes effective. You then don't have to think about it during the roll when you are fighting with the rudder to maintain the centreline. Then feel for the wing lifting and keep it down, hold aileron on during rotate and start feeling for wing drop and control it as the aeroplane yaws and settles into drift.'

Magic technique that worked on the 747, 737 and 757. It works. The fact there was a stickshaker/tailstrike incident on this particular take-off leads me to say there were other factors present. No way should a medium crosswind have induced that. I would be more interested in examining speed, rotation rate and rotation angle reached. Not any nonsense about blaming aileron control during roll! (speaking from the POV of an 18 year 747 pilot from a fleet of 57 of them doing regular high weight flights, with no T/O tailstrikes!)

Rainboe, agree 1000% !

My first jet was B707 - 436 which did not have a "series" yaw damper so you had to take off and land with the yaw damper not engaged. I learned a lot about crosswind technique from this type. I cringe when I see pilots conducting a cross wind take off and not applying any into wind aileron and/or taking the aileron out during rotate - the aileron input should be maintained during the rotation maneuver and then the controls smoothly centred once safely airborne.

When I did a (refresher) conversion onto the B737-800, a very experienced pilot instructor from SAS was of the opinion that in limiting crosswinds FULL aileron should be applied during rotate to keep the wings level!

Major cause of tailstrike is excessive rotation rates - Boeing recommend on B 737-800 an average of 2.5 deg/second - this means it takes 6 seconds to achieve 15 deg pitch up.

NoJoke
4th Nov 2008, 01:19
I fly a 'Bus' and have always applied a little into wind aileron (secretly). Now it is 'allowed'; marvelous. The other thing I used to advocate was adding a couple of knots on the 'bugs' on gusty approaches (remember the little buggers - sad joke), and being told "no way, think of .... this and that", now we have GS mini. QED. It has taken over 25 years to have certain points proven.

zerozero
4th Nov 2008, 02:24
I fly the 747-200 as an FO.

Can't say that I've experienced every possible condition of flight but the Classic is so nice to fly it doesn't take any special technique in a crosswind takeoff.

Just enough aileron to keep the wings level--as Rainboe noted, the upwind wing will want to lift up.

I think, a lot of pilots with weak "stick and rudder" skills are very reluctant to cross the controls--I find rudder skills in particular the weakest.

So in the original case mentioned above, I can imagine an FO being timid on the rudders, trying to overcompensate with aileron (35 degrees!) and then the shifty wind (8 kt average tailwind component) all making things very edgy on a heavy airplane.

Back to Basics!

Big, powerful, high tech airplanes still need to be flown using fundamental skills.

nugpot
4th Nov 2008, 06:36
I see a lot of posts talking about the drag of a slightly deployed spoiler/spoileron. I don't think that that is the main contributor to a possible tailstrike.

A spoiler (by definition) spoils the airflow over a wing, causing less lift and thus a higher angle of attack for the same lift required. Higher AoA equals higher body angle at rotation.

All that said, I think the total effect of a slightly deployed spoileron due to upwind controls is probably negligible, unless there are further aggravating factors like in the example in the first post.

mustafagander
4th Nov 2008, 08:33
From the report - see post #1 - it seems that s/he had an evil combination of reducing x wind and increasing tailwind at the worst time. Sure, we all know that on 4 we rotate just a bit slower in x wind, but it seems that s/he copped a "gotcha".

All this "do it by the numbers" stuff - I don't know, what about look out the window and keep straight with enough rudder and hold the upwind wing down with enough aileron. I'm not smart enough to remember fancy formulae - as the sports shoes say, "just do it".

Remember to add a shmick more aileron as you lift off and rotate consciously more slowly (on 4) and it will work out. BUT things may just conspire against you one day! Sorry, that's the aviation game!!

Intruder
4th Nov 2008, 11:03
I see a lot of posts talking about the drag of a slightly deployed spoiler/spoileron. I don't think that that is the main contributor to a possible tailstrike.

A spoiler (by definition) spoils the airflow over a wing, causing less lift and thus a higher angle of attack for the same lift required. Higher AoA equals higher body angle at rotation.

All that said, I think the total effect of a slightly deployed spoileron due to upwind controls is probably negligible, unless there are further aggravating factors like in the example in the first post.
It appears that many here are losing sight of the big picture...

It doesn't matter if you use upward aileron or spoiler; EITHER ONE causes loss of lift on the wing! That's why the wing drops when you use EITHER ONE!

If you use the amount of aileron AND/OR spoiler that is required to keep the airplane level and keep the engine pod off the ground, you are doing your job as a pilot! If you use too much, you are hurting yourself as much (or more) than if you use too little. Just FLY THE AIRPLANE, even when it is on the runway! If you're looking at the aileron trim indicator on the yoke after starting your roll, you're likely trying to follow some book theory instead of flying the airplane.

Those who have done it a few thousand times might even note that when you properly ease and release the slight cross control (required in many transport airplanes) during/after rotation, the airplane naturally settles into most of the upwind crab that you need to maintain runway track. If it isn't happening for you, you may have to adjust your technique a bit.

Rainboe
4th Nov 2008, 11:09
The incident I was involved in on a 747 take-off concerned a strongish crosswind up to copilot limits. I was surprised he was not applying any aileron at all. Regarding it as too late to teach someone to suck eggs (at 100kts), we continued. Just after lift off, there was what felt a horrendous wing drop and I can't describe too much more as it all happened so fast. The aileron required was almost full, and we were over the side of the runway. I suspect we were caught by a gust on lift off just as the copilot had still not applied any precautionary correction. The amount of aileron to hold wings level (and the duration) startled me. The reaction of the third pilot was 'what the hell happened there?'

Next time you do a crosswind take-off where the other pilot does not apply aileron, or not enough, during the roll, clock the amount of aileron needed as the main wheels lift off. What was 'saved' during the rotation will be doubly applied after rotation. I can guarantee the aileron will be hard over, at least double or more the planned setting, and the HP will be unaware how much he has had to apply to hold wing level. When you try and explain how much they actually put on, you will be met with disbelief.

Summing up, the point I really want to get over is:
Drag from spoiler uplift is negligible up to climb speed, especially on the roll.
You need to stop that wing lifting on the roll, even at lowish speeds.
Lift off with little or no aileron, into a medium crosswind, and you're in for a surprise.

Once again, the reasons for the United incident are absurd. The wind conditions are no more than 'moderate'. Quite plainly, blaming that for the tailscrape is nonsense. When you have done 35 kt crossswind take-offs in gusty conditions at max weight regularly as part of a very large fleet doing the same, with no tailscrapes, then it shows the reason lies elsewhere!

TopBunk
4th Nov 2008, 11:32
Basic rule of thumb given to me by an old timer (possibly one of Rainboe's ex colleagues) when I converted to the 744; 10kts x-wind? Hold 1 unit (control wheel aileron trim indicator) of into-wind aileron; 20 kts-2 units etc. and that's right from the start of the takeoff roll.

S'funny, I was always taught 1 unit of into wind aileron per 5 knots of crosswind, not 1 per 10 kts (on the 744 and Boeings in general).

Phantom Driver
4th Nov 2008, 11:40
Intruder:
If you're looking at the aileron trim indicator on the yoke after starting your roll, you're likely trying to follow some book theory instead of flying the airplane..

Reread the post,do it before start of the roll; goes without saying that you adjust accordingly as required during the takeoff (not often needed; how many times do we do a max crosswind takeoff? Not very!). I also pointed out that this was an "Old Timer's Rule of Thumb", i.e basic starter guide for newcomers to the type in order to keep out of trouble. Never a substitute for basic airmanship/flying skills; merely a backup. Would save a lot of grief if applied more often in everyday flying; (e.g inputting/ selecting wrong V speeds.....??!!)

Top Bunk:

S'funny, I was always taught 1 unit of into wind aileron per 5 knots of crosswind, not 1 per 10 kts (on the 744 and Boeings in general).Not going to argue about 5 knots! Who knows what the actual wind is anyway?Initially you are only going by what the tower is telling you, and we know how reliable or otherwise that can be. You'll find out soon enough during the takeoff; that's where the Airmanship bit comes in.:rolleyes:

fireflybob
4th Nov 2008, 11:50
Rainboe, good post again! Agree totally!

Also I say that if you are going to make any mistakes apply a bit too MUCH into wind aileron rather than not enough. The effect of spoiler deflection on lift is, I agree, quite negligible and is of much lower priority than just keeping the wings level during rotate.

I suppose I am quite sensitive about this having started on the B 707 where if you did not get it right you would end up scraping a pod! (Also applied to the landing).

All we are talking about is normal crosswind take off technique for virtually any a/c - back to basics!

GlueBall
4th Nov 2008, 12:53
Have flown many hours on 74s and still flying, but I've never "preset" the ailerons during takeoff roll even in moderate x-winds, and I don't allow my copilot to preset ailerons.

Nobody can predict what the wind vector/gust/shear value will be 2 miles down the pavement from brake release. But during rotation I have always found that there is adequate and instant aileron authority available to counter any wing from coming up. Haven't had a pod strike nor a tail strike.

BOAC
4th Nov 2008, 13:45
It seems that (in GENERAL, NON-TYPE SPECIFIC) terms, we are split between the 'painting-by-numbers' folk and the 'fly-it' folk. I am with the latter and glueball's post says it all - for me. However, it is what you are comfortable with/made to do that counts. One cannot say what is right or wrong for an individual.

WindSheer
4th Nov 2008, 18:33
I understand that airbus sidestick inputs command roll rate and not just aileron deflection?
When does this 'law' come into effect? I assume that as soon as the a/c becomes airborne the computers attempt to roll the a/c at a rate relevant to the amount of sidestick applied.

Is this correct? Does it completely alter the technique over conventional machines? :confused:

TopBunk
4th Nov 2008, 18:57
BOAC

Wouldn't disagree, but as always it is useful to have a datum to hang your hat on as a point from which to start, and it is much more critical on a highly swept wing like the B747 vs the B737.

Windsheer

My recollection of the A320 family (3 years since I last flew it), it that 'normal' law blends in at 100ft AGL on take off (at which point sidestick deflection becomes a roll command vs an aileron position demand / direct law / conventional aircraft) and that shortly after touchdown, the aircraft reverts to 'direct' law. I hope that makes sense. I can dig more into it, but am off for a curry!

In effect that means that you can hold into wind aileron on the take off roll and after landing it is beneficial to again put some into wind aileron in to stop the wing lifting.

fire wall
4th Nov 2008, 19:37
Gents,
Done correctly the X wind takeoff is a thing of rare beauty. Problem is I rarely see it done correctly and given that I fly ultra long haul ( so sector count is an issue) it ends up being a verbal discussion with the FO after the event. Some want to learn , others .....
I have flow the 757,767,747 classic and now the 744 and the technique is identical. Preset a small amount of aileron and fly the wing down the runway. Use rudder to keep straight. As a result of the swept wing design the into wind wing has a resultant less angle of sweep than the downwind wing and produces more lift for a given angle of attack so, during a SLOW rotation (MAX 3 deg/sec) , apply an increase in into wind aileron otherwise the wing will lift. When away from the ground slowly neutralise control forces and the aircraft will beautifully weathercock into wind and track on the extended runway centerline.
I will add that the 744 wing starts working at 60 kts hence the need to preset the aileron.
As to the debate of how much aileron, use what you need and forget about the spoiler deployment. You are going to look a meathead explaining to the Chief Pilot the pod strike on 1 or 4 because you were concerned you may have too much drag due spoiler deployment. To counter the loss of effeciency re the boards up use a slow rotation - simple huh?

Boeing releases Flight Operational Reviews which from memory detailed spoiler deployment on the 767 was at 2.4 units control wheel deflection and 744 I think was 2.2 units - critics be gentle with me on this as the grey matter is not what it was. At times when parked at the passenger terminal with those shiny windows get clearance from the your man on the ground, pressurise the hydraulics and let the FO displace the control wheel and note in the reflection from the windows when he detects spoiler pick up - works better than just telling him at what # of units it will happen.

BOAC
4th Nov 2008, 20:00
TB - as I said - it is for the individual 'comfort level' rather than a 'must do'. I have flown far higher wing sweeps than any airliner with far greater 'lifting' tendencies, and my PERSONAL technique has been to fly the a/c. The into-wind wing does not just start 'lifting' at rotate.

On the subject of 'comfort', I am not comfortable with 'it's 2.5 units for this wind and that's it' which I have seen develop into nasty rolls one way or the other when the rotation wind ain't the same - and sadly the thinking process isn't there either:).

This is all rather like 'how you must do a crosswind landing', isn't it?

411A
4th Nov 2008, 20:59
...both B707 and L1011, with strong crosswinds (35 knots) at heavy weights.

Spool up engines evenly and release brakes..
Add aileron into wind as necessary to keep the upwind wing from lifting.
None of this 'preset' aileron business, ever.
At Vr, delay rotation by a few knots, thence commence a slow(er) rotation than normal, using whatever aileron is necessary to keep wings level.

Sometimes, full upwind aileron is needed.
Once airbourne, turn into the wind, to make good a straight runway track.

Note: With early models of the B707, slightly uneven thrust initially is desired...IE: lead with the upwind engines.

In no case, however, will I plan to become airbourne at less than V2, in either type.

Don't fly new(er) types, so can't comment about those.

NB. I was taught to fly the B707 by old time PanAmerican pilots, who first flew the type, in 1958.

Chris Scott
4th Nov 2008, 21:40
Quote from WindSheer:
I understand that airbus sidestick inputs command roll rate and not just aileron deflection?
When does this 'law' come into effect? I assume that as soon as the a/c becomes airborne the computers attempt to roll the a/c at a rate relevant to the amount of sidestick applied.
Is this correct? Does it completely alter the technique over conventional machines?


No, TopBunk is right. We had a discussion on A320 crosswind techniques in the Spring, remember? Here's a link to something I posted, with the help of other PPRuNers on the same thread:
http://www.pprune.org/tech-log/316096-lh-a320-rough-landing-hamburg-24.html#post3979423

Quote from the above:
CROSSWIND TAKE-OFF
A small amount of into-wind aileron can be selected before starting the T/O run, avoiding "cracking" the spoilers.* [U]During rotation, the upwind wing tends to rise in the conventional manner, and can be countered by retaining into-wind aileron. As the main L/G lifts off, any downwind rudder will be eased off, yawing the aeroplane into wind. This will temporarily assist the aileron. Half a second after lift-off, however, Normal Law in roll is introduced (AND the white cross on the PFDs has disappeared). At that point, any remaining roll input needs to be released.
5 seconds after main L/G lift-off, Normal Law also becomes fully effective in pitch. Stick-to-elevator control is now removed, and pitch-attitude can be refined by small nudges of sidestick.
* Roll-spoiler deployment can be avoided by placing the PFD white-cross so that its inner edge is not noticeably to the side of the centre spot.
[Unquote]
I can't guarantee that the precise timing of stick-to-aileron removal is still correct, as I don't get the FCOM amendments these days.

So the standard technique still applies until properly airborne, and I'm with you, Rainboe and TopBunk on that. Most jets seem to offer a small amount of aileron without cracking the spoilers. The only one I flew that didn't was the B707. on the A320, pre-setting the maximum before starting the take-off run using the white cross and/or the F/Ctl page on ECAM enables you to concentrate on looking out and flying the aeroplane. Flying the aeroplane includes controlling roll, but that should not happen on a modern jet until you start to rotate (I don't regard the 707 as "modern").

In over 10 years doing line checks on the A320 (mainly from the jump seat), the most common handling error I saw was the upwind wing rising on rotation, countered by the belated use of sidestick. If the wing rises while stick-to-aileron is still in effect, Normal Law will not subsequently recover it for you. Despite the aerodynamics of the A320 being boringly conventional, the powers-that-be insisted that any into-wind aileron should be removed at rotation: i.e., BEFORE the mains had left the ground. :ugh: That's the point when you usually need it most...

411A,
Your technique just what I was taught by AA on the B707 in 1975 works well, and preset aileron is not a good idea on the 707 because any aileron cracks the spoilers. But it does mean using more runway, and we had little to spare coming out of LAX to LGW on a warm day with 189 punters. [Have you voted yet?]

BelArgUSA
4th Nov 2008, 22:00
I am much more concerned, in the 747, as to scrape an outboard engine after rotation when compensating with excessive bank into a crosswind situation. To drift away from initial alignment with runway flight path is not critical. I rather accept a (say) 5 drift to the left or right, after lift-off.
xxx
Same story with the 707 and DC8...
xxx
Outboard engine scraping incidents seem more related to crosswind situations, tailstrikes are not. Boeing does not provide any specific procedure in their 747 FCTM regarding crosswind. I have a kept an old 1982 edition FCTM for the 747, which contains much more data than newer editions, and I often find answers in the older manual than what is printed in the new edition. In example there is a graph "Aileron/Spoiler Deflection Vs. Aileron Trim" on the old manual page 05.40.08... Try to find this, in a new FCTM...
xxx
Training briefings and classroom discussions, in the subject of crosswind handling, do depend much of the experience each individual pilots. I do not preselect a certain amount of trim for aileron (or rudder) for crosswind. And further, do not come with "nosewheel steering compensation" as it is worthless at high speed. Nosewheels are "as effective for directional control, as a piece of wet kleenex tissue".
xxx
To avoid a tailstrike, in a 747, remain at 10 pitch nose up limit... and to avoid scraping an outboard engine, do not bank more than 5 on ground at Vr speed, and be careful on crosswind gusts. The primary aerodynamic control in crosswind takeoff and landings, remains the rudder.
xxx
:8
Happy contrails

TopBunk
4th Nov 2008, 22:10
BOAC

I have flown far higher wing sweeps than any airliner with far greater 'lifting' tendencies, and my PERSONAL technique has been to fly the a/c. The into-wind wing does not just start 'lifting' at rotate.

BOAC, I'm not saying we disagree, but what were the wingspans of the aircraft you flew with greater sweep angles?

BOAC
5th Nov 2008, 08:22
TB - the first point of my post was The into-wind wing does not just start 'lifting' at rotate.As with many things in life, it is not how big yours is, it is what you do with it. Each to his/her own?

warmkiter
5th Nov 2008, 09:07
Hi Guys

A lot has been said about using aileron for x-wind T/O in a B744

Some guys who have never flown the type seem to have a pretty good idea how to do the trick.

Here some aspects you might consider for your own technique

1. You will need Aileron!

2. Preseting some Aileron into the wind before commencing T/O roll has zero effect on aircraft, because lack of speed But has a nice "mental" effect : you and your other crewmembers have to make some thoughts about where the wind may come down the road.

3. When the aircraft picks up speed, you will see how much is the correct amount and adjust accordingly. Gusts, increasing effectiveness of controls change the required input during the T/O roll constantly. But with a little aileron in your "mind" you dont get cought by suprise. Correcting too late and too much makes it harder than it is.

4. If you start the T/O roll with zero aileron, you will be suprised how easily such a big plane reacts on X-wind. Its a bit tough to recognize how much bank you get, because you sit high, all the windows have different angles and dont help much as a reference to ground and going on instruments doesnt help maintaining centerline either. Its just a wobbly feeling if you dont counteract the x-wind.

5. for liftoff you should have wings pretty much level, you had them during the take-off roll level so why not now? getting blown a bit away from the centerline is not as expensive as getting your plane scratched during rotation. Achieve a nice crab after liftoff.

6. forget all this talk about degrees, how much spoiler deployment you get, and therefore lack of performance, slow rotation. and so on. x-wind take off is not made by numbers, its flown by feeling. The time to react and usable reference is too limited to fly it by numbers. Look out of the window, you just need some aileron thats it, the rest remains the same. If you are interested when the spoilers open, just check CMC, flightcontols page and look on lower EICAS during flightcontrol check or taxi. You will never need such a control column input if you stay within the max x-wind limits for T/O.

Happy fuel flow

Lars

Centaurus
5th Nov 2008, 13:00
When I did a (refresher) conversion onto the B737-800, a very experienced pilot instructor from SAS was of the opinion that in limiting crosswinds FULL aileron should be applied during rotate to keep the wings level

I wonder if that very experienced pilot instructor from SAS had the fortitude to write to Boeing stating he had done measured tests during line flying and that full aileron was needed and that Boeing should henceforth accept his recommendations against the Boeing test pilots figures....

Very experienced pilots sometimes have a tendency to have their own personal gimmicks and swear by them.

Phantom Driver
6th Nov 2008, 13:13
Warmkiter


x-wind takeoff in B744


Just about sums it all up, whatever aircraft you fly. Now time to move on to the next topic?!

PantLoad
7th Nov 2008, 14:59
One of my pet peeves is to see the 'crab' introduced prior to lift off.

Fly safe,

PantLoad

misd-agin
10th Nov 2008, 15:13
1. Boeing tests takeoff performance without spoilers or aileron deflected. If you're not on the drag profile they certified, especially on a balanced field, you're a test pilot and on your own.

2. They recommend aileron as necessary to keep the wings level.

3. A plane at rest needs no cross controls. At rotation it will need the same amount of cross controlling that it would have if you were landing.

4. Understand #3, observe the wing 'lifting', and gradually apply #2, not to exceed #3.

411A
10th Nov 2008, 19:47
1. Boeing tests takeoff performance without spoilers or aileron deflected. If you're not on the drag profile they certified, especially on a balanced field, you're a test pilot and on your own.

2. They recommend aileron as necessary to keep the wings level.

3. A plane at rest needs no cross controls. At rotation it will need the same amount of cross controlling that it would have if you were landing.

4. Understand #3, observe the wing 'lifting', and gradually apply #2, not to exceed #3.

Yup.
Younger folks should read, and understand the above.
Especially important on older types, IE: B707, L1011 as well.