paulyg123

Cross wind landing question

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I watch many cockpit videos.   This is a crosswind landing.

Look at this video at 2:40 secs.   

https://www.youtube.com/watch?v=UhO1BeC7m10

Why is he truring the yoke full left while on the ground?  I know he is jumping on the rudders, but why the arelons?  I tried to replicate this in a crosswind, I ended up lifting my right gear all the way off the ground.

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Just using proper crosswind technique. On takeoff and landing you want to deflect the ailerons into the wind. It helps with directional control and to keep the upwind wing from possibly lifting off early. In my opinion, ailerons have too much authority on the ground and cause the plane to roll more than they should. To compensate, just use less control input. Especially at higher speeds when the controls are more effective 

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It's to prevent the wing from lifting on the windward side.

On takeoff, you would crank aileron into the wind to prevent the windward wing from lifting before the leeward wing got to flying speed (the windward wing will fly before the leeward wing).  You add the cross control and reduce it gradually until you have no aileron input at liftoff.

The opposite with landing...you add more and more cross control as you slow down until you have full deflection into the windward wing.

It's taught in the most basic flight training and is quite important in light aircraft to prevent the windward wing from flying too soon and causing loss of control.  You even do it while taxiing in strong winds with small aircraft to prevent them from flipping.

P3D/FSX does not simulate this very well, and as Adam said, the ailerons have too much authority at low speed in the sim.

Edited by netshadoe

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OK - thanks for that explaination - I knew you guys would know this.  

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For what it’s worth, this is not proper technique in the Boeing Flight Crew Training Manual, at least for the 757/767. The issue in using aileron deflection on the ground during takeoff and landing is that, during takeoff for example, if you deflect the ailerons then the spoiler panels also extend which seriously degrades takeoff performance. The opposite happens on landing. Aileron deflection in one direction causes the spoiler panels on the opposite wing to close which increases landing distance. 

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Same for 737/747 Sean, I've not watched the video but the technique mentioned in used in all GA aircraft I've flown but the heaviest of those come in around 12000 lb  MGW.  This technique is not applicable to transports in general.

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59 minutes ago, downscc said:

Same for 737/747 Sean, I've not watched the video but the technique mentioned in used in all GA aircraft I've flown but the heaviest of those come in around 12000 lb  MGW.  This technique is not applicable to transports in general.

I figured as much, Boeing technique is pretty standard across models, I just didn’t want to assume. We did use the traditional crosswind technique when I flew the EMB-145, but it didn’t have roll spoilers so it was pretty much like flying a big Cessna or Piper. 🙂

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This would need @berts to confirm but oddly enough I was having a discussion about crosswind technique with a very senior ex-747 pilot the other day and he was very much of the opinion that in-to-wind aileron for both takeoff and landing was very important, and I am inclined to agree.

The FCTM agrees as well - whilst one does not want so much control wheel deflection as to cause the roll spoilers to come in to play, the advice is to apply sufficient in-to-wind aileron to maintain wings level, lift off with crossed controls and smoothly neutralise the aileron and rudder as one becomes airborne.

And don't stop flying the aircraft just because the main wheels have touched down!

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1 hour ago, skelsey said:

This would need @berts to confirm but oddly enough I was having a discussion about crosswind technique with a very senior ex-747 pilot the other day and he was very much of the opinion that in-to-wind aileron for both takeoff and landing was very important, and I am inclined to agree.

The FCTM agrees as well - whilst one does not want so much control wheel deflection as to cause the roll spoilers to come in to play, the advice is to apply sufficient in-to-wind aileron to maintain wings level, lift off with crossed controls and smoothly neutralise the aileron and rudder as one becomes airborne.

And don't stop flying the aircraft just because the main wheels have touched down!

He obviously gave you some very good advice, Simon! 

The 747-400 and -8 are no different to any other large jet transport as far as the crosswind takeoff and landing technique is concerned.  Here are a couple of other useful tips to bear in mind.  At light weights and aft CG there is less weight on the nosewheel and so care is needed to maintain directional control; for example by making sure the engines spool up symmetrically and observing the crosswind limit of 15kts on contaminated runways (i.e. standing water/ice/slush). 

On slippery runways the crosswind capability is a function of airplane loading, runway surface conditions and pilot technique, so during the landing it is not necessary to eliminate the crosswind crab angle prior to touchdown.  But it is important to keep the wings level at all times so as not to scrape an engine pod and don't allow the aircraft to float or aim for a smooth touchdown. The advantage of keeping the crab angle on until touchdown means there is less likelihood of the aircraft drifting downwind from the runway centreline. However, after touchdown watch out for any tendency for the aircraft to weathercock into wind when the autobrake and reverse thrust are applied, because they will only exacerbate the problem and risk a potential sideways runway excursion. 

Edited by berts
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Worth bearing in mind too that some aeroplanes reduce the amount of aileron authority available when there is weight on the wheels, meaning that you have to really 'give it some' to get a good amount of aileron control; the Airbus A320 is an example of an airliner which does this when its systems go into 'ground mode'; when it is in this mode, the aileron control authority of the aeroplane is halved. This is intended to assist in preventing engine pod strikes during crosswind landings, just in case the pilot forgets to, or is slow to take off a large aileron deflection input upon touchdown.

As an aside, it's interesting to note that some Airbus variants (A318 and A319) can also have an aileron modification added to their software when they go into ground mode after landing which causes both ailerons to deflect upwards so that they act as additional spoilers to keep the thing on the deck and provide a bit of aerodynamic braking drag too. This mod tends to be fitted on variants which will operate from very short runways, such as those found at London City and Florence. In fact, this modification is sometimes called the 'florence kit'.

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10 hours ago, swood721 said:

For what it’s worth, this is not proper technique in the Boeing Flight Crew Training Manual, at least for the 757/767. The issue in using aileron deflection on the ground during takeoff and landing is that, during takeoff for example, if you deflect the ailerons then the spoiler panels also extend which seriously degrades takeoff performance. The opposite happens on landing. Aileron deflection in one direction causes the spoiler panels on the opposite wing to close which increases landing distance. 

 

10 hours ago, downscc said:

Same for 737/747 Sean, I've not watched the video but the technique mentioned in used in all GA aircraft I've flown but the heaviest of those come in around 12000 lb  MGW.  This technique is not applicable to transports in general.

I'd hate to tell you guys, but in the 74 you do apply aileron input.  You start to 'fly' the aircraft on the ground and its important to maintain level wings throughout rotation and after landing, as that wing will snap up in a crosswind if you aren't careful and bring the pods ever closer to the ground.

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12 hours ago, thibodba57 said:

I'd hate to tell you guys, but in the 74 you do apply aileron input.  You start to 'fly' the aircraft on the ground and its important to maintain level wings throughout rotation and after landing, as that wing will snap up in a crosswind if you aren't careful and bring the pods ever closer to the ground.

We're on the same page, I assumed perhaps incorrectly that the control deflections being discussed were for taxi operations.  Landing is a different subject and if that was what they are talking about then I'm inadvertently stepping on the conversation.

Yup.... wings level landing most swept wings.  Light aircraft with Hershey Bar wings are different, kicking out the crab is performed simultaneously with dropping the upwind wings to stop the crosswind drift but this is a different subject.

Edited by downscc

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On many small aircraft, all above on those without fron/tailwheel steering, you even use the ailerons as a directional control during taxi. The downwards aileron creates more drag than the upwards aileron and will slowly move the airplane to its side. So when you have a wind on your nose but slightly from a side and the airplane wants to turn into the wind your ailerons can assist your brakes and rudder to stay on the taxiway. 

Floatplanes without a water rudder use this effect quite efficiently.

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22 hours ago, thibodba57 said:

 

I'd hate to tell you guys, but in the 74 you do apply aileron input.  You start to 'fly' the aircraft on the ground and its important to maintain level wings throughout rotation and after landing, as that wing will snap up in a crosswind if you aren't careful and bring the pods ever closer to the ground.

Interesting. My airline teaches to keep the ailerons neutral on the 75/76. I know the Boeing manual says that input may be applied but our manual says not to due to the possibility of putting to much aileron in and raising spoiler panels.

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1 hour ago, swood721 said:

Interesting. My airline teaches to keep the ailerons neutral on the 75/76. I know the Boeing manual says that input may be applied but our manual says not to due to the possibility of putting to much aileron in and raising spoiler panels.

I've never flown the 75/76 so can't comment on it.  But we keep the aileron input thru rotation even on a engine failure panels or not.  I suspect we have a tighter tolerance on pod strikes than the 75/76 especially on the 748.

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On 2/19/2019 at 11:00 AM, Chock said:

Airbus A320

🧐 what the devil....! Who goes there... sin bin; 10 minutes 🙂

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On 2/19/2019 at 8:54 PM, thibodba57 said:

I've never flown the 75/76 so can't comment on it.  But we keep the aileron input thru rotation even on a engine failure panels or not.  I suspect we have a tighter tolerance on pod strikes than the 75/76 especially on the 748.

Very cool. Always interesting to find out the variances between different airlines and aircraft types.

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On 2/20/2019 at 4:54 AM, thibodba57 said:

But we keep the aileron input thru rotation even on a engine failure panels or not.

Quite right too!  No matter what type of commercial jet aircraft you are flying, one of the priorities during every takeoff and landing roll is accurate directional control and in order to do this - especially in a crosswind - it will be necessary to apply sufficient rudder and maintain wings level in order to keep all of the main wheels on the runway surface.  Keeping the wings level is particularly important on aircraft fitted with podded engines (including the 757, 767), where the engine to ground clearance is much less when compared to those fitted to the HS146.  Boeing's recommended technique for use of the ailerons is to maintain wings level throughout the take off and landing roll by applying sufficient into wind aileron as necessary.  The amount of aileron displacement required will obviously decrease as the airspeed increases - and vice versa. 

Probably the most important point in all of this - especially in gusty conditons - is to 'feel' what is happening to your aircraft and to 'fly' it by maintaining proper control at all times; i.e. anticipating and then responding correctly to the conditions you find yourself in.  Provided you are positioned correctly within the cockpit of your aircraft then more often than not the top of the instrument panel will give you a very good horizontal reference to compare with the natural horizon outside - which is one of the many reasons why the correct seat position is so important on the B747.        

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My 2cents worth..

I’ve flown the 737/747 and although the Boeing FCOM/FCTM have similar techniques as mentioned above for the 757/767 too. Lifting spoilers must be considered (drag) and normally the procedure for me was to maintain wings level control input (spoilers down) until the wing that’s into the X-Wind begins to fly first. At this point gently roll the controls into the wind to keep wings level. On the 737 this is usually around rotation, on the 747 depending on the X-Wind component it can be well before rotation. Once you become one with the airplane that you fly it’s surprising how you will know when it’s time to apply some control input into the wind. It becomes a natural thing. 

On landing drag is good but I usually only applied as must aileron as needed to keep wings level. And yes the 747 wing keeps flying for quite sometime after touchdown.

IM

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