Turbulent Approach Less Flaps

[Chally604]

Dear all,

I know that people suggest that you reduce Flaps one step when flying an approach with severe crosswind or turbulent air.

I did it my self cause I copied the procedure. Now I do question it and would like to collect different aspects and point of views and would like to understand the aerodynamic reason.

Can anybody help a little?

Thanks
Frank

[hetfield]

- less drag
- better L/D ratio

Aircraft will respond quicker if losing airspeed.

[Prazum]

I'd imagine the bigger surface area given by flaps means you are more susceptible to catching more of the turbulent air. I'm trying to recall something about turb. Conditions giving more rise to stalling. With the landing configuration and less flap your decreasing your chances of both of the above.

[bucket_and_spade]

More importantly...

Less likely to get a flap exceedance i.e. the lower flap setting usually comes with a higher limit speed i.e. gusts and large variations in IAS won't result in the flap load relief system operating or an exceedance requiring some paperwork or, worse, engineering inspection.

Was always my take on it...

[Chally604]

Ok, Thanks!
Some interesting points.

I see the point with the increased drag. In this case of full flaps you are more a "leaf" in the wind than with less flaps, is that what you mean?

And I see the speed limit point. But here is the next question:
Lets say you have Vref 130 Wind 30 gusting 45 (as per handbook you make additional half wind plus full gust up to a max of 20kts), meaning 130+15+15 = (130+15+the remaining 5 due to max 20) = 150kts.

Will you still add the the increment of, lets say, 8kts for lower flap selection and make it to a total of 158kts?

Best
Frank

[bucket_and_spade]

Hi Chally604,

Not sure what the 8kts is for?

In my aircraft flap 30 limit speed is 162 knots.

At heavier, but sometimes even normal, weights our Vapp (Vref for flaps 30 plus half the stead headwind plus the full gust) will be uncomfortable close to this. In these cases we might use flaps 25 for landing as the limit speed is much higher. If we did this we'd use a Vapp of Vref for flaps 25 plus half the steady headwind component plus the gust.

Boeing say bleed of the steady headwind addition at some point before landing (i.e. between the threshold and the flare) but keep the gust addition.

Any help?

[Chally604]

Coming closer ;-)

The 8 knots are stated in the QRH as a supplement for a flap selection less than full flaps.

Actually it is 7kts for flaps 30 instead of 45 and 14kts for flaps 20 instead of 45.
This is stated in the QRH for non normal operation like single engine (F20) or stuck Flaps etc...

Now I wonder if if you would basicaly say:

Ok, Flaps 30 instead of 45 gives me an additional 7ktd as per QRH + the 20 addition due wind from the example above... Or you say:

Well I have an additional 20 anyhow and I dont care about the 7 from the QRH.

But as those 7kt are related to performace and the 20 are related to weather, I guess you are better of to add both to a maximum of 27 what you do for example in this situation as well:

Singe engine - Flaps 20 - Vref plus 14.
In case you have 30 gusting 45 you would take:
Vref 130 + 15 (half steady wind) + 5 (15kts gust but as to max 20kts its only 5 knots remaining) + !!14!! (for the flaps 20 situation) =130+20+14=164

[1975]

On the aircraft I fly, the 'G' limit is less with more flaps, that may be a consideration also, it is a 20t turboprop

R. 1975

[sevenstrokeroll]

sure, I heard the idea many,many years ago that you use less flaps in certain situations...

with the exception of certain engine out situations in certain planes, and flap malfunctions...


I would not change the flap setting at all. I would use the maximum flap setting authorized by the manufacturer/FAA all the time.

Why?

So, there you go...flying for years using full flaps for landing and now , for the first time in years you use less flaps...you're doing something not routine...and you are more likely to screw it up.

you are more likely to hit the nosewheel first
you might use more runway than you have available
you might be less spooled up (in a jet) and be less able to correct with power.

you will have less of a chance to see the runway off an ILS


the idea that you will have more G loading protection is sort of odd, but it is very unlikely that you will encounter turbulence that will exceed your g limits. (in 37 years of flying, I have had two turbulence events that might be called severe...never seen extreme and much of my flying has been near the highest peaks in the 48 contiguous states.

so...why not just do what you are doing all the time...certainly add the wind/gust corrections to VREF

be on your toes ( literally too)
learn how to use assymetric thrust a bit on multi's

but every landing you ever did with full flaps is that much more experience when you really need it...otherwise you might as well do partial flap landings all the time (you'll be sorry)

[Pub User]

Chally

On jets it is quite common to use less than maximum flap for landing, for a variety of reasons, not least of which is it saves (a small amount of) fuel, but also because of the risk of overstressing the flaps in gusty winds.

We always fly the appropriate Vref for the flap setting used, then add the wind additions to that. On a 737 the FMC gives a Vref for flaps 40, 30 and 15, and we use the relevant one as a baseline, with the appropriate wind increment on top.

No idea what the Scarebus does.

[Lord Spandex Masher]

...

So, there you go...flying for years using full flaps for landing and now , for the first time in years you use less flaps...you're doing something not routine...and you are more likely to screw it up.

Not very flexible then

you are more likely to hit the nosewheel first
Why?
you might use more runway than you have available
Don't you check your landing performance?

learn how to use assymetric thrust a bit on multi's
Talk about something not routine!!

but every landing you ever did with full flaps is that much more experience when you really need it...otherwise you might as well do partial flap landings all the time (you'll be sorry)
I do, except where performance dictates otherwise
"..................

[JammedStab]

I would not change the flap setting at all. I would use the maximum flap setting authorized by the manufacturer/FAA all the time.

Why?

So, there you go...flying for years using full flaps for landing and now , for the first time in years you use less flaps...you're doing something not routine...and you are more likely to screw it up.

you are more likely to hit the nosewheel first


It seems to me that with lesser flap, you are in a higher nose up attitude requiring less flare and less likely to hit nosewheel first.

[stilton]

I started using F25 instead of F30 on our B757's years ago, this is allowed in our procedures and was suggested to me one gusty night while being given a line check.


I was so impressed at how much easier it was to handle in these conditions with this reduced flap setting that I use it as a matter of course, runway length allowing.

[Pontius]

Chally604,

In addition to controllability issues, by using less flap you will have a higher approach speed which will have the effect of reducing the size of the crab angle for your crosswind approach. Not usually a huge factor in planning your approach but if you're working to limits, as Tesco says, every little helps.

[Pontius]

you are more likely to hit the nosewheel first

SSR,

I assume you wrote this because you thought that by going faster you'd have a lower body angle. However, assuming you are flying at the correct speed for your flap setting, you will have a lower body angle with greater flap settings and I would have thought that would increase (very slightly) the chance of doinking the nosewheel first, as opposed to less flap.

[9.G]

it's rather simple. Higher energy means better coping with the disturbance, better controllability and less crab angle. :ok:

[sevenstrokeroll]

no...because as you float along, using your ''normal'' flare technique and not quite touching down,, you panic and push the plane on, but oops, you push too much and you land flat.

the FAA does require minimum flap for jets to reduce noise, but it is a legitimate landing flap setting not some reduced flap setting just out of your head.

if you have never used assymetric thrust, you don't know all the tools you have available.

it seems to me that boeing would publish different crosswind limits for different flap settings if it really made a difference...

my comment is about departing from routine...if you are in the habbit of pulling up just a bit as the ''numbers'' vanish, or the thousand foot marker vanishes beneath you, you may float.

if you are disciplined enough to just fly it on the runway with the reduced flap setting fine...but I"ll bet someone in your company will float a bit more trying for that smooth touchdown..

and of course lord spandex masher is right and I am wrong...why? because he wears spandex and we all know how irritating spandex is

[Turbavykas]

Easy question :) It's even easier to answer when you try to fly airplane. I fly gliders myself though I have CPL but no job...
When you fly in turbulent air you want bigger wing loading, smaller coefficient of lift and better controllability.
Flaps will increase coefficient of lift and wing area so it's opposite what you want. So the airplane will feel any gust and will be even more difficult to control. So that's why in gliders we land with landing flaps in normal days and +2 in windy days. Also at the beginning of the tow we use -1(yes gliders have negative flaps) so you don't hit ground with wing tip which is a foot from the ground and wingspan is almost like on 737...
Also on turbulent days I prefer to fly with water ballast so I don't get sea-sick. Water ballast increase wing loading so glider is not going up and down in the smallest updrafts.
I hope my answer explains the question :)

[Chally604]

Woooww...

Are we all all in the same industry? :}
As I posted this, I was guessing I will get two answers:
1) Idiot why dont you know?
2) Do it this way and go back to the books...

But this turned out not to be THAT easy.
Interesting. I can follow most inputs logically but I get the feeling it is more personal attitude than airmen ship or procedure.

I guess I might continue using less flaps as I had 40 gusting almost 60 in a quiet small plane a few days ago. I used on flap setting less and I was surprised how easy to flare and to land the plane was.

the last 3 ft over the runway turn out to be quiet calm anyhow.
Was one of my best landings ;)

Best
Frank

[Pontius]

no...because as you float along, using your ''normal'' flare technique and not quite touching down,, you panic and push the plane on, but oops, you push too much and you land flat.

Good to see you hold your professional pilot colleagues in such high regard :hmm: An alternative to your suggestion, that most of us mere mortals might carry out, would be to hold the attitude and allow the aircraft to settle. If it's going to land long then we go around. No need for theatrics and certainly no need for pushing forward, which we've been taught not to do from day 1 (despite some recent events in NRT :rolleyes:)

the FAA does require minimum flap for jets to reduce noise, but it is a legitimate landing flap setting not some reduced flap setting just out of your head.

Who suggested anything of the sort? What we're talking about is going from flap 30 to flap 25 in your 757/767 or from flap 40 to flap 30 in a 737. They're 'legitimate' flap settings, not 'just out of our heads' and achieve what the OP was asking about.

Since you're so concerned that we're doing non-standard things and this is going to end in tears, please point me to the Boeing Training Manual where it discusses using asymmetric thrust in any part of operation, bar trying to stop on slippery runways. I'm willing to do so with reduced flap settings.

[sevenstrokeroll]

please remember that I said it might be harder off an ILS to see the runway...the nose is upp a bit more

and that flaps 25 on the 757...I know a guy who did that and ended up pranging the tail

so...good luck brave airman...don't float, panic and pushover too much...but don't hold off too much and prang the tail

there is wisdom in knowing how much wind affects your plane at particular airports too and if the annemometer is mounted at a non standard height...knowing how the trees, buildings etc can suddenly blank the wind is worthwhile too

[sevenstrokeroll]

pontius...colleagues in high regard...I am a realist...if it can go wrong, it will...too many ''incidents'' of less than perfect airmanship

as to assymetric thrust...if you don't have it in your bag of tricks woe to you if you are in a sioux city situation or a rudder hardover and out of options, or otherwise faced with something unusual

and using a bit of assymetric thrust, whether in the manual or not (it does say that the manual is for an experienced pilot) on a crosswind landing, allows for a reserve of controlability.

ahhhh...those across the pond...hmmmm

[sevenstrokeroll]

what kind of plane did you have in mind with your original post?

[Lord Spandex Masher]

SSR you've gone from landing on the nose wheel to pranging the tail. Do you actually know what you're talking about?

Sioux City?! I thought we were talking about landing in turbulence and not catastrophic failures.

[Centaurus]

Boeing say bleed of the steady headwind addition at some point before landing (i.e. between the threshold and the flare) but keep the gust addition.


So how do you bleed off 15 knots (1/2 the HW component) in the few (seven seconds?) between crossing the threshold and the flare? On the other hand, the 737 FCTM does say (if landing with ice on the wings) that 10 knots should be added to the final approach speed. It further states this 10 knots should be bled off from 200 ft down - not between crossing the fence and flare. Some inconsistency by Boeing, maybe?

[Chally604]

The Original Problem was in relation to a Challenger 604.
So believe me.. I can see the runway as long as I do not crap 90 degrees ;)
We are coming with almost negative attitude and need to do a serious flare to get the nose up for a main gear landing.

But this is not the problem.

I am more worried about the "bouncing around" in the wind. we have 20 meters and 35.000 lbs weight during landing.

So there is nothing like "energy" which will keep you going no matter what.

Out of my point of view now, it doesnt make too much sense for us for speed reasons:

Flaps 30 max 197
Flaps 45 max 189

When you add the additional 7 knots to F45 for less flap setting you end up with you won 1 single knot. 189+7=196

Guess it might be more comfortable anyways as you are further away from Stall speed and have a little more energy.

[sevenstrokeroll]

spandex...yes,I do know

I know that when you do ''different'' things you open yourself up to errors...heard all the excuses...well that's the way i do it with flaps x



and it is different, in different types.

so good luck to you spandex...have lots of fun

oh and original poster...

one way to make turbulence easier to cope with is for the PILOTS to make sure they have their seat belts on very tight, becoming ''one'' with the plane. it can reduce turbulence induced over controlling.

[Robert G Mugabe]

Airbus 319 and 320 FCOM recommend CONF 3 ( less flap ) for turbulent conditions.

Some folk would prefer to use Flap Full mind.

[Dg800]

Flaps will increase coefficient of lift and wing area so it's opposite what you want. So the airplane will feel any gust and will be even more difficult to control. So that's why in gliders we land with landing flaps in normal days and +2 in windy days.What you're saying there is only half true, actually. Bigger planes do indeed have lift augmentation devices that increase both the camber and the surface area of the wing, thus a higher flap setting will really give you a larger surface area and so a lower wing loading, which makes the plane more susceptible to turbulence. Vice-versa a lower than full flap setting will give you a higher wing loading which makes it somewhat more manageable in severe turbulence, also because of the small increase in speed, which gives you higher kinetic energy, a smaller crab angle and increased control authority, as already mentioned in previous posts.
On gliders you only change the camber and hence the lift coefficient, the surface and the corresponding wing loading does not change. Ideally with severe turbulence you should retain your water ballast (=higher wing loading) until you've landed, this is however discouraged if not outright forbidden in most glider's POH for structural reasons, so you just set the flaps to "full minus 1 stop" for the increased speed and aileron authority.

Ciao,

Dg800

[yippy ki yay]

I would not change the flap setting at all. I would use the maximum flap setting authorized by the manufacturer/FAA all the time.


flying for years using full flaps for landing and now , for the first time in years you use less flaps...you're doing something not routine...and you are more likely to screw it up.

as to assymetric thrust...if you don't have it in your bag of tricks woe to you if you are in a sioux city situation or a rudder hardover and out of options, or otherwise faced with something unusual

IMO being competent at landing with any of the recommended landing flaps for your aircraft type should be extremely routine! In my bag of tricks I'd much rather have the ability and confidence of landing with any of the landing flaps than being proficient at using asymmetric thrust! What if you can't select maximum flaps for whatever reason?

[Lord Spandex Masher]

spandex...yes,I do know

Strange then that you warn us of hitting the nose wheel first if we use less flaps and on the other and regale us with a story of a guy you know who had a tail strike.

So which is it?

[ImbracableCrunk]

IMO being competent at landing with any of the recommended landing flaps for your aircraft type should be extremely routine! In my bag of tricks I'd much rather have the ability and confidence of landing with any of the landing flaps than being proficient at using asymmetric thrust! What if you can't select maximum flaps for whatever reason?

I agree. I recently flew with two Captains who nearly had a conniption when the computer suggested a F1 takeoff, rather than our usual F5. I'd rather take every opportunity to perform the F1 takeoff or vary F30 and F40 landings.

[sevenstrokeroll]

so, I know a DC9 incident of striking the nosewheel
and a 757 incident of hitting the tail. both reduced flap settings
and of course you can't realize my point...change something and you are closer to a problem...unless you are on top of things...and of course I can see you on top spandex

[Lord Spandex Masher]

Your odd vision aside how do you know that "they" had "changed" something?

Do you always use exactly the same everything?

[sevenstrokeroll]

trying for a correct landing all the time is something worthy of a pilot's attention...changing an element may, i say again, MAY lead to a problem.

[blind pew]

Can't believe the posts here from professionals!

Use Full flaps on a jet in turbulent conditions only.

Main Reason. - faster thrust response....

You win with wind shear and when you touchdown it is easier to kill the bird.
And if you need to go around the engines are already spooled up.

The rest is a load of cods wallop.

[bubbers44]

I never felt the need to use less than normal landing flaps unless a procedure was required to preclude using normal flaps. Sometimes in a small GA aircraft it made landings easier but not in an airliner. I only had one FO change flap settings to less than normal when I pointed out a rain squall close to our landing runway and to be prepared for some possible shear on approach in a 757 so he asked for flaps 25. I gave it to him but wouldn't have if it were my leg. It got a bit sporty when he floated down the runway trying to get it on the ground.

Every pilot needs to fly so he feels comfortable using his technique as long as it is approved. 23,000 hrs with no dings makes me stick with what works for me.

[Lord Spandex Masher]

Bubbers, if you were the captain it was your leg. Anyway it was his technique that lead to the float not less flap. Also I believe flap 25 is normal on a 757.

Faster thrust response hey. What difference does a few percent here or there make? Measure it, if you can!

Windshear. No config changes. So you're happy to carry extra drag when you could do without are you!? Riiiiiiiight. The aircraft can also handle higher gust loads with less flap. Besides my FCOM says use flap 30 NOT 40.

[9.G]

the levels of education and technical understanding seems to vary significantly among the so-called professionals, why not simply follow FCOM? :ok:

[bubbers44]

Spandex, your I am the captain attitude has shown throughout your posts. I always let the FO fly the way he wanted to. I only intervened when it was outside my comfort zone. Why couldn't you. Sometimes you learn from what your FO does differently.

I don't think you learned anything from your FO's, I did by watching. They had a different learning experience and sometimes you can learn from other pilots if you are not obsessed with yourself.

Try it sometime. You might learn something.

[bubbers44]

Landing flaps on a Boeing 757 is 30 by the way. You don't have your facts right on this so probably don't on your other aircraft either.

[punkalouver]

Spandex, your I am the captain attitude has shown throughout your posts. I always let the FO fly the way he wanted to. I only intervened when it was outside my comfort zone. Why couldn't you. Sometimes you learn from what your FO does differently.

I don't think you learned anything from your FO's, I did by watching. They had a different learning experience and sometimes you can learn from other pilots if you are not obsessed with yourself.

Try it sometime. You might learn something.

Bubbers, seventrokroll....ignore this fellow. He always posts like this and must be just awful to fly with let alone post with. No doubt hated by his colleagues.

No doubt another reasonably knowledgeable type that fails to realize what a hazard to aviation his personality is. Extremely poor CRM is a hazard.

How about the rest of of you continue the conversation in a respectable adult manner as an example to him of how he could be.

[bubbers44]

Yes, I THINK WE WILL DO AS SUGGESTED.

[Lord Spandex Masher]

Bubbers,

Why couldn't you.
What makes you think I couldn't?

I don't think you learned anything from your FO's,
You can tell that from some words on an anonymous forum. Power to you pal!!

Try it sometime. You might learn something.

Try this - Stop taking yourself and pprune so seriously.

Landing flaps on a Boeing 757 is 30 by the way. You don't have your facts right on this so probably don't on your other aircraft either.
Another statement devoid of intelligence.

Is flap 25 approved for landing on the 757? Yes or no.

Punkalouver, is CRM required for posting on pprune? If you haven't got anything to add to the topic then why are you posting? I'm sure little Bubbers can stick up for himself oh great protector.

[punkalouver]

Bubbers,


What makes you think I couldn't?


You can tell that from some words on an anonymous forum. Power to you pal!!



Try this - Stop taking yourself and pprune so seriously.


Another statement devoid of intelligence.

Is flap 25 approved for landing on the 757? Yes or no.

Punkalouver, is CRM required for posting on pprune? If you haven't got anything to add to the topic then why are you posting? I'm sure little Bubbers can stick up for himself oh great protector.


Well....I guess I will add that you sure proved me to be 100% correct. O.K. everyone....how do you spell ignore _ _ _ _ _ _ _

[deltahotel]

Landing flaps for 757 and 767 can be 25 or 30. If you're close to MLW worth giving F25 serious thought (bigger margin to flap exceedance speed). Certainly on smaller unswept ac, but haven't noticed on bigger types, the flaps bring the CoP inboard, thus reducing stability in roll, so having a lower flap setting increases stability - relevant in gusty conditions.

[aerobat77]

you are more likely to hit the nosewheel first
you might use more runway than you have available
you might be less spooled up (in a jet) and be less able to correct with power.

you will have less of a chance to see the runway off an ILS



uuuh... changing weather or view settings may help in seeing the runway , but the idea of using more of it than available really is only something for outdoor camping fans, i agree !

a very odd method to prevent all this catastrophics might be using the correct approach speed for the reduced flap setting i would quess ?

cheers !

[sevenstrokeroll]

I SHAKE MY HEAD at this thread...BUBBERS ... I KNOW BUBBERS IS A VERY EXPERIENCED AIRLINE PILOT...NO QUESTION ABOUT IT>

Punkalover...you seem to know your stuff and I respect it.

There is a simple way to understand flap useage. OUR forefathers in aviation knew that the higher the landing speed...the more potential for problems ( and no, don't go blaming tailwheels)...THe slower you can safely land the better, and VOILA FLAPS

Bubber's example bout the FO floating away the runway is exactly my point.

Having more flaps makes the engines do more work and VOILA are more able to respond quickly to either windshear or goaround(or even bounced landings...but that is another thread).

MORE flaps means you will stop better, using less wheel brakes, your brakes will stay cooler for the next takeoff if there is a quick turn.

And yes, if your FLIGHT MANUAL says do something...chances are YOU SHOULD DO IT THAT WAY.

sheesh...spandex must be wrapped around this guys brain!

[Lord Spandex Masher]

Floating down the runway is not an effect of a lower flap setting. I'm sure if you look you'll find examples of floated landings with full flap - I've witnessed a few. Poor technique is what causes a float.

I cant see anything on this thread by Pinkerlover that displays a knowledge of "stuff".

We have brake cooling schedules in our QRH and can adapt accordingly.

So, when I said my FCOM says use flap 30 not 40 in windshear you agree with that? If so why must my brain be wrapped in spandex, unless, of course, yours is too!

P.S. No need to shout chap, we can read just as well without capitals.

[BARKINGMAD]

From the dregs of my memory when having brain drained and chip-detection done by CFS aeons ago, the phrase "spanwise distribution of lift" oozed out.

Apparently the more flap, the more the majority of lift moved inboard reducing the effect of the ailerons and adversely affecting roll control per degree of control column/stick deflection.

Whether this still applies to our exotic multiple roll-spoiler shiny craft I am blissfully ignorant, and await educating further.............

Yes, a higher flap setting means higher average thrust and rpm in the event of a sudden need for energy input, though the greater drag of that flap setting must offset that advantage in the event of a go-around, surely the craft will reach the G/A flap setting slightly later, delaying the increase in energy input?

For those on this topic who seem to think there is only ONE land-flap setting, why does Mr Boeing for example have 3 flap settings with 3x VsREF in the FMS for the 73s various? I appreciate the F15 setting is for non-normals, but my last 4 companies permitted either of the other 2 settings, depending on LDA or whether a lower attitude was needed for LVOs visibility over the glareshield.

Finally, old classic 747 drivers may recall Mr Boeing advised using F30 on the Jumbo where possible, later in its life, after large sections of flap assembly were dropping into peoples gardens as a result of fatigue exacerbated by regular use of the maximum setting!

A lie-down in a dark room beckons again, after exercising what's left of my neurons, during the usual winter hibernation of a contract-trash airframe manager.

[bubbers44]

All of us have done thousands of landings and know how to do them successfully every time. Now we have people that think we should have been doing it differently? Why? We did it the way the book said to do it. It worked so well we didn't change anything. What is wrong with that? 40 years of flying with no problems makes me think some of us old guys maybe know WTF we are doing.

[Lord Spandex Masher]

By the book? Well the book has changed. Do keep up.

Maybe all those years of experience have shown the likes of Boeing and Airbus that there are better ways of doing things. Ever think about that? Or would you like to stay rigidly stuck in the 70s?

[bubbers44]

None of my aviation books were writen in the 70's. My Boeing 757 and 767 manuals were written when they were manufactured, not before. Once again you have shown you can't show any credibility, just BS. Do a lot of your Fo's put you on their do not fly list? If I was a lot younger, I would.

[Pontius]

My Boeing 757 and 767 manuals were written when they were manufactured, not before.

What do your 757 & 767 manuals say about landing flap settings? What does your FMC say?

Flap 30 AND flap 25 are both perfectly normal flap settings and there are very good reasons for using both.

[bubbers44]

SSR has a lot of experience and respect. I think we should pay attention to what he says. He knows what he is talking about.

[Lord Spandex Masher]

Bubbers, dear chap, were you or were you not flying 40 years ago? That was the 70s, you said you've never changed the way you do things, that means that you must still be doing things you were doing in the 70s. If you didn't mean that then why say it?

What revision are your manuals on? Has the content never changed?

I think that the person who doesn't know which are approved flap settings on his own aircraft has no credibility whatsoever. That's you by the way.

Finally can you please not turn this into some kind of American love in? Bubbers is really good this, SSR is very experienced that...if our want to back slap and high five each other do it in private, hoo yah! Fawning is soooooo last year.

[aerobat77]

Finally can you please not turn this into some kind of American love in? Bubbers is really good this, SSR is very experienced that...if our want to back slap and high five each other do it in private, hoo yah! Fawning is soooooo last year.

i just spilled my coffee with a laugh . really cool comment !

and i see the usual pprune +20000 hours airliner captains are also already here. uh, it might get a bumpy flight :ok:

[con-pilot]

Finally can you please not turn this into some kind of American love in? Bubbers is really good this, SSR is very experienced that...if our want to back slap and high five each other do it in private, hoo yah! Fawning is soooooo last year.

So instead, I see you prefer to change this to your typical 'bash' all people that disagree with you thread. :rolleyes:

Use the flap settings that book tells you to use. Can't be any simpler than that. Once you change standard FAA/Company/manufacturer's procedures, you cease being a line pilot and become a test pilot. We are not paid to be test pilots.

Except of course if you are paid to be a test pilot. :p

[Lord Spandex Masher]

Con, I haven't "bashed" anybody, on this thread at least.

Blowing somebody else's trumpet as if it's some kind of show of force isn't really the best way to counter argue is it now.

Besides, people aren't just disagreeing with me they're disagreeing with aircraft manufacturers AND the test pilots.

Sheesh, I knew Americans were sensitive but not this sensitive.

P.S. I have done test flights for my previous company but wasn't paid in kind:suspect:

[bubbers44]

Spandex, I guess this could go on forever so maybe we should just say "use your own judgement on what flap setting you want as long as it is legal and safe". It would be nice if you didn't PO your FO if he didn't do something the same way you would safely. I always let them because they are going to be in my seat soon and hopefully when they get there they won't act like you do. Have a nice life.

[Lord Spandex Masher]

Spandex, I guess this could go on forever so maybe we should just say "use your own judgement on what flap setting you want as long as it is legal and safe". It would be nice if you didn't PO your FO if he didn't do something the same way you would safely. I always let them because they are going to be in my seat soon and hopefully when they get there they won't act like you do. Have a nice life.

Or you cold say use the recommended flap setting.

You seem to think you have some mystical insight into my operating style. Why do you think my FOs are POd? Where did I even hint, let alone state, that I wouldn't allow them to do so? Finally, how do I act on the flight deck?

Come on, just some irrefutable proof for your statements is all I ask. I won't hold my breath though because you ain't got any. Just silly attempts at put downs.

Still think most people agree with you?

You've still not answered any questions put to you since you stated:

Landing flaps on a Boeing 757 is 30 by the way. You don't have your facts right on this so probably don't on your other aircraft either.

Anything to say about that now?

[bubbers44]

I turned in all my books 9 years ago but recall flaps 25 for an overweight landing and 15 for single engine approach, otherwise 30. We were also 767 qualified so with no books am unable to research it. I always landed flaps 30 even at the special airports we had. TGU was the most restrictive airport our airline flew into in Honduras and I chose that one because it was a lot of fun and challenging. TGU made number one of the most dangerous airports in the world to fly into with a jet airliner on a TV show.

If you want to see my retirement flight in 2003 go to Flightlevel350.com: Free Aviation Videos, Airplane Videos and Cockpit Videos (http://www.flightlevel350.com) and search MHTG. I am the 7th video down. We couldn't return with an engine failure because flaps 15 wouldn't give us enough runway. It had 5400 ft useable. We had to use a military base 30 miles away if necessary.

You probably aren't what you project yourself as so will give you a break. We all just want to retire and go fishing.

[sevenstrokeroll]

first off, I know bubbers 44...and in the small world of aviation, internet and the like, to find someone WHO knows someone I KNOW and knew about his flying business and could only learn it while flying with him at AIR cal and later on American...i am convinced that bubbers knows his stuff and his a real airline pilot.

and yes, if you want to fool around and use another flap setting, go right ahead...some of you will do fine...others may go off the end of the runway, prang your tail, or your nosewheel...and I only hope it goes on YOUTUBE so I can see it.

and for those flying little planes, do what you like...you probably won't die...too much.

but spandex..you have a real 'tude about you...and I love it, cuz it proves to me that i was right about those BA guys flying their 747 from LAX to whoops almost london on three engines...yup...couldn't make it all the way.

and PRUNE>..do what you like...make my day...and overcome warp drag if you can.

[Lord Spandex Masher]

Bubbers, enjoy your fishing.

SSR,
i am convinced that bubbers knows his stuff and his a real airline pilot.

Nobody has suggested otherwise so what are you waffling, in poor English, about?

and yes, if you want to fool around and use another flap setting

It's not fooling around if it's an approved setting. Just because there are pilots in this world who are comfortable and experienced with both doesn't mean it's wrong or dangerous or even slightly risky. If you can't be flexible, adaptable or capable enough to use both then don't. Fine.

but spandex..you have a real 'tude about you...and I love it, cuz it proves to me that i was right about those BA guys flying their 747 from LAX to whoops almost london on three engines...yup...couldn't make it all the way.

What?! Irrelevance follows irrelevance. Did you forget your pills today? Again WTF are you on?

[con-pilot]

TGU was the most restrictive airport our airline flew into in Honduras

You went into TUG, what the hell, so did. But I was flying 727s, -100s.

But I cheated, we could still go flaps 40 if we, the PIC, deemed it necessary.

And there, I did. :p

We carried a little crescent wrench in the FE table, couple of turns, off came the flaps 40 blocking pin.

Interesting place, Tagup was.

[bubbers44]

Spandex, typos are allowed on this so don't be rude again. Thanx fer lissning.

[bubbers44]

con-pilot: So did I. That 727-100 had nose wheel brakes but we couldn't land to the south because of go around performance. The 757 could. What a great airport. I loved it and the people. Over 600 landings, all with zero problem. Watch my video to remember how fun it was.

[bubbers44]

"Or you cold say" is proper english in England? Maybe it was a typo also. When you get off that high horse you are on come back.

[con-pilot]

Over 600 landings, all with zero problem

You win. :p

I probably only had about a dozen, it was not one of our regular runs, only went there a few times a year and I wasn't on all of them. The nose brakes had been removed on all three of our 727s. Never got to spend the night there. The trips were all straight down there, then deadhead home.

The other two places I would use flaps 40 was SBA and EYW. We would use those airports when Vandenberg AFB and Navy Key West were closed.

[Lord Spandex Masher]

Yes Bubbers that was a typo, well not even a typo more of an autocorrect that wasn't correct. Well done for picking it out.

I'm talking about SSRs first paragraph. Incomprehensible and poor grammar and I still don't understand it after the tenth attempt. The last part I did understand despite the typo that I didn't even see the first time.

Maybe you could also translate his very last sentence.

[bubbers44]

If you can't figure out the typo how can we?

[aerobat77]

thats all fantastic gents , i highly enjoy the reading from all this highly experienced veterans being here.

[If you want to see my retirement flight in 2003 go to Flightlevel350.com: Free Aviation Videos, Airplane Videos and Cockpit Videos (http://www.flightlevel350.com) and search MHTG. I am the 7th video down. We couldn't return with an engine failure because flaps 15 wouldn't give us enough runway. It had 5400 ft useable. We had to use a military base 30 miles away if necessary.

superb landing, good job ! i looked hard to see you, but damn, i saw only a plane landing and filmed by a spotter like thousands filmed every day.

nevertheless- may i also share my flapless landings with you ?
visit YouTube (http://www.youtube.com)

search "sts128"

i,m the 7th video below, like you was in your link.

see- no tailstrike , no nosewheel , no floating, no engines spool up. but we also were limited in our go around performance.

cheers gents !

[bubbers44]

Look for the video out the front of a 757 cockpit window filmed by my friend who retired as a check airman the same month and we went with him going to Madrid two weeks earlier. Maybe it shifted to seventh spot or close to it.

[de facto]

Ohh and look at me,,me ,me me:E

[sevenstrokeroll]

but spandex..you have a real 'tude about you...and I love it, cuz it
proves to me that i was right about those BA guys flying their 747 from
LAX to whoops almost london on three engines...yup...couldn't make it
all the way.
THE ABOVE IS SIMPLY PUT SAYING THAT YOU ARE QUEEN OF BRITISH PILOTS>>>AND THAT MAKES ME HAPPY...I used to think British Pilots were of the Hurricane mold...but you are of the mold of flying the atlantic on 3 engines when you are equipped with 4.




and PRUNE>..do what you like...make my day...and overcome warp drag if
you can.


AND THIS MAKES ME REALLY HAPPY...IT MEANS I DON'T CARE WHAT THE PPRUNE MODERATORS DO...AND WARP DRAG...THIS PROVES TO ME THAT YOU HAVE ALOT TO LEARN...THE WRIGHT BROTHERS KNEW WHAT THIS WAS...ITS THE SAME AS ADVERSE AILERON YAW...(DRAG WHEN AILERON OR IN THE WRIGHT'S CASE, WING WARPING WAS USED)


SPANDEX...CHEAR UP...FLYING IS FOR THE BIRDS

[bubbers44]

df, I wish I knew what you are talking about.

[punkalouver]

Punkalouver...you seem to know your stuff and I respect it.




I cant see anything on this thread by Pinkerlover that displays a knowledge of "stuff".



Perhaps you should look more carefully at your immature posts and my statements about them. It is obvious that I know exactly what I am talking about.

As for your private message to me questioning whether anyone was actually ignoring your posts....it appears that many are now judging by page 4 so far. Lets all do this on PPrune.

Too bad, you do have some knowledge but ruin your ability to pass it on to others by your awful personality. I hope you are not an instructor.

I suggest you read Mr. Tullamarine's posts on how behave in a manner deserving of respect. Likely too late I always remain hopeful.

[haughtney1]

Gosh, 4 pages of chest thumping...I know better than you...

FWIW, this is straight out of my B777 FCTM..latest revision..and is identical to the same passage in the 757/767 FCTM.

Flap Setting for Landing
For normal landings, use flaps 25 or flaps 30. When conditions permit, use flaps 30 to minimize landing speed, and landing distance. Flaps 25 provides better noise abatement and reduced flap wear/loads.
Note: Runwaylength and condition must be taken into account when selecting a landing flap position.

Last time I looked

[stilton]

Some pretty amazing posts :rolleyes:


F25 or 30 as has been stated numerous times are approved flap settings
on the 75 / 67.


There's about 3 knots difference in approach speeds, not an issue on most runways !


F25 gives you considerably better controllability in the 757 with gusty winds, that wing has so much lift already you don't need it all on a blowy day.


It's also quieter and uses less fuel.


Why do you think Boeing installed it ?!

[gatbusdriver]

Too right stilton.

I have to say I think LSM has spoken the most sense.

Flap 25 is a perfectly normal flap setting (20 for S/E by the way!). Some companies specify its use as part of fuel saving measures, we don't (yet). I generally use it in gusty conditions and heavy weight as with a Vref30+20kts you can get very close to your flap limit speed of 162kts (752).

Anyway enough of this.......anyone seen my video of when I......

[Lord Spandex Masher]

SSR,

So you've never heard of a three engine ferry then? It's just after the chapter about flaps and windshear.

Of course I know what adverse yaw is. I just don't know what it's got to do with this thread, pprune or the moderators.

It is obvious that I know exactly what I am talking about.
Is it.
As for your private message to me questioning whether anyone was actually ignoring your posts....it appears that many are now judging by page 4 so far.
Well? Did everyone agree with you about ignoring me? Did they all jump on your outrage bus with you? Hey wait, if you're ignoring me...?!

[Pontius]

So you've never heard of a three engine ferry then? It's just after the chapter about flaps and windshear.

Oh, don't rise to his bait or we'll be bombarded with more irrelevant nonsense, as if wing warping wasn't bad enough. To guys like SSR there's only ONE way to do something and anything else is just wrong. Flap 25 OR flap 30, don't be so ridiculous. Let's ignore what Boeing do recommend and, instead, suggest other techniques e.g. asymmetric thrust which, for some strange reason, seems to be missing from the manufacturers' manuals.

Never mind that Boeing, British Airways and the CAA all approved the steps taken by the LAX 747 crew and never mind that all 3 on the flight deck went through all those approved steps and decided to do what they did, SSL is telling us they were all wrong and he knows. There's only one way to operate an aircraft and that's SSL's way, with one flap setting, wing warping and asymmetric thrust :rolleyes:

I'm glad between the likes of Stilton, Masher, Gatbus etc we've established that using a reduced flap setting is (a)a perfectly normal means of operating an aircraft safely (b)is approved and recommended by the manufacturers (who seem to know a bit about the subject and (c)helps to achieve what the OP was asking about in the first place.

I think I'll leave it at that, lest the chaff dispensers return.

[Lord Spandex Masher]

Just giving him more rope Pontius!

[JammedStab]

F25 gives you considerably better controllability in the 757 with gusty winds, that wing has so much lift already you don't need it all on a blowy day.




Thanks for the info.

Any drivers of other jet types with info on whether controllability is in their opinion better at a reduced flap setting for strong gusty crosswinds.

[tom775257]

On the A320 series I find flaps 3 better for gusty/crosswind etc than flaps full (as per the manual). At the airline I work for SOP is now flaps 3 for approaches if full not required, due to fuel savings.

[yippy ki yay]

I have found, in 737, that F30 seems to be easier to control in a gusty crosswind than F40.
On a side note this brings up a question that I've always wondered about and I have received 2 different answers from different people ( so maybe pprune isn't the best place to ask!!) but here it goes. When you're extremely light, ie. positioning an empty aircraft, what's your preferred landing flap? And why? (Assuming runway length, weather, wind etc. isn't a factor)

[aerobat77]

controllability is in their opinion better at a reduced flap setting for strong gusty crosswinds.

correct.

honestly, its so obvious for any real pilot with work experience that reducing flap settings to a minimum needed and approved on a gusty day with a strong crosswinds helps a lot and is a common procedure, that basicly in real life nobody from a flight deck would start a debate about it.

so this thread of course went after few postings stupid with no useful information.

the only thing which makes it worth reading is the fun about all the dreamers here who continue to debate in which direction ever and fail to see that seriously debating this obvious question by itself for several days proof them to be very fake and never had a crosswind landing on whatever aircraft.

for a real pilot , even a private one with some hours logged, its not a question if its a better idea to land a cessna 172 with flaps 40 or flaps 20 when a strong and gusty wind from the side blows.

cheers !

[bubbers44]

With your vast experience at 35 yrs of age guess you must be right. Yes the Cessna 172 lands better with reduced flaps in a gusty wind situation but how has your experience in a Boeing 777 been doing the same thing. I will give you 20 years to answer.

[Lord Spandex Masher]

Well at least he's up to date!

Any drivers of other jet types with info on whether controllability is in their opinion better at a reduced flap setting for strong gusty crosswinds.

Embraer 170+ series, 737 300 and 800, 146 100-300. CRJ 200. All better with reduced flap landings.

[bubbers44]

Spandex, get over yourself. I know you are number one for you but the rest of us don't GAS.

[Lord Spandex Masher]

Nothing to do with me Bubbers. You belittle someone for only being 35 and use sarcasm to refer to his experience, something you know nothing about. On the same thread you claim you have 23,000 hours and 40 years experience but you don't know which are approved flap settings for the aircraft that you claim you used to fly. Yet I am the one who has to get over myself?!

You've been proved wrong on this thread numerous times by numerous posters. Your experience is out of date. I hope you're better at fishing.

Perhaps you should retire gracefully.

[RAT 5]

"When you're extremely light, ie. positioning an empty aircraft, what's your preferred landing flap? And why? (Assuming runway length, weather, wind etc. isn't a factor)"

I've tried F30 & F40 in these conditions. My initial thoughts were F40 because at light weights the N1% is about the same as F30 i.e. mid 50's. This would give better engine response for speed control. It is definitely better if there is a tailwind otherwise the N1% would be well below 50%.
At F30 I expected N1% to be too low and not give such easy speed control, but in fact it was not too bad.
Suck it and see.

[bubbers44]

flaps 20 on 757, flaps 15 0n 727 on an engine out approach. No sim checks in over 9 yrs makes these numbers meaningless. Brain cells are meant to handle present day problems, not what age 60 rule said you couldn't fly an airliner any more but try to remember every flap setting you will never use again because you are too old.

I am not bitter about the rule because it was there when I got hired at 35. I just know what I know now vs age 35. Yes, I flew Lear Jets and Jetstars and tons of twins but flying for the airlines was the final learning process that completed my career. It makes you really take your job seriously.

[sevenstrokeroll]

sure...no problem...but NO "BOOK" authorizes three engine ferry with passengers aboard.

and sure, it might have been legal to fly from LAX to ALMOST London on three...but what about common sense?

keyword ALMOST London. they didn't make it.

[Pontius]

it might have been legal to fly from LAX to ALMOST London on three...but what about common sense?

keyword ALMOST London. they didn't make it.

Common sense: there's nothing else wrong with the aircraft, even if the aircraft loses another engine all terrain can be covered, there's countless alternate airports enroute if another engine fails, there's sufficient fuel on board to reach a decent airport enroute, it's an approved 'manoeuvre' by the manufacturer, company and safety regulator and, lastly, ALL the crew agree the same thing. There's plenty of common sense in all of that and just because your dyed-in-the-wool thinking won't allow you to think any more than Flap 30 doesn't mean the crew were mistaken in their actions nor worthy of your derisory comments.

No, they didn't make it to London but, guess what Einstein, they KNEW that was going to be the case before they were halfway across the US. Amazingly, even without your expert knowledge being available, they were able to figure out their course of action which ended up with a perfectly safe flight, less inconvenience for the pax and an easier repatriation of the machine. I know you hate anything across 'The Pond' but I reckon the the operator of the largest number of 747-400s in the world might have just an inkling as to what they're doing....even if asymmetric thrust was not part of the syllabus.

[Lord Spandex Masher]

Ah, of course not but you didn't qualify your statement before.

No they didn't make London, mainly due to unforecast winds, but Manchester is a lot closer than the states, any of it.

I understand that the FAA rolled over on this.

[bubbers44]

The FAA rule is if you have two engines and lose one you have to land at the nearest suitable airport. If you have more than two engines you can continue as long as it as safe as landing at the nearest suitable airport. Continuing across the Atlantic was legal by FAA standards as long it was as safe as landing at JFK. You be the judge. I wasn't there so have no opinion.

[Lord Spandex Masher]

What's the CAA rule?

[Meikleour]

Pontius: I suggest you revisit the AAIB report on that flight. They had some very choice observations to make about the then -400 fuel balancing procedures that were in force in BA at that time. (they were at variance to the Boeing procedure) This is what led to the diversion landing short of LHR. The legally required total amount of fuel was indeed still onboard - it just was not in the correct places hence the crew`s concerns. IIRC BA were told to instigate appropriate training plus change their manuals.

(The crew were using the Jettison pumps to maintain balance - this works fine until you get to stand-pipe level...................)

[sevenstrokeroll]

gee spandex...you seem to have made a mistake

oh...and I know its "legal" to do what the crew did...

its legal to do alot of things.

and common sense is not all that common.

so fly the atlantic with one dead, land with any flap setting you like, but just when you have done what's legal, and something unexpected comes up...THINK OF ME, GRINNING.

[Lord Spandex Masher]

gee spandex...you seem to have made a mistake

Errrr what would that be then? Apart from wrestling with pigs.

land with any flap setting you like

Why would I do that?

Grinning or gurning?

[thermostat]

I tried several times to log in using the same password but was unable to. Finally I got in. Is there something wrong with the site????????
How do I contact the webmaster directly if I have a problem????
Thanks.
Thermostat

[thermostat]

I seem to remember that the drag goes up with the square of the lift. If you double lift, the drag goes up four times. Triple lift and the drag goes up NINE times. So the more flap you use, the more lift you produce but the drag goes up quite a bit (with the square of lift). During turbulent approaches, if flap is reduced, drag is also reduced, speed is increased and that helps to improve approach and go-around performance if required.
I well remember the L1011 that crashed going into Dallas years ago. Got into a microburst and couldn't maintain the flight profile. It's possible that a reduction of flap may have saved the day.
T

[Pontius]

Meikleour,

I agree 100% regarding the fuel situation and things did change as a result of the incident. To be fair to the crew, at the time, the manuals were not very clear on a couple of the finer points of the fuel system but that has been rectified and I'm confident the situation in which they found themselves would not happen nowadays.

For what it's worth, the incident shouldn't even be in this thread. I only wrote about it because of SSR's bigoted accusation of what they did was wrong, because it doesn't conform to what he would have done. The actual flight has been done to death on PPrune and it's clearly got nothing to do with flap settings, so hopefully that'll be an end to it :ok:

[Meikleour]

Pontius: Thanks for your reply.

THE LAW OF UNINTENDED CONSEQUENCES

My personal interest in that incident stems from my own experience many, many moons ago when I worked for one of the companies that became BA. Your loyalty to BA is understandable however that company has always had a tendency to change/rewrite perfectly good manufacturer's manuals into their own version. I was very nearly caught out by just such a situation involving an emergency gear extension which did not work as per the BA drill and indeed the poor -400 crew were let down in a similar manner.

I do however draw the line at your assertion that the flight was perfectly safe when in the end the crew felt that they had to declare an emergency!!

Going back to the original thread - the various manufactures go to great lengths to produce operating procedures that work and do not require "exceptional pilot skill" therefore there should be no need to debate the merits or otherwise of different flap settings. I am fully aware that some individuals will always know better however.............

[bubbers44]

The poor guy that initiated this thread is probably more confused now than the beginning. I would say if the operating manual says you need to or can use discression on flap settings and your op specs agree do what works best for you. I personally usually used the max setting unless performance required otherwise but others feel differently. Never once had a problem using that procedure. As long as it is legal who can fault you?

[FullWings]

I think there is lot of argument (some healthy) over this subject as there isn't really a 'right' answer that covers every aircraft type, runway and weather condition.

In no particular order, here are some of the things that might be considered on a bumpy day when choosing a land flap setting in a jet transport:

Advantages of lower flap setting:

* Higher Vref gives greater control authority
* Less drift angle
* Less drag, so better performance in windshear
* Often greater margin to flap limit speed
* More fuel efficient

Disadvantages:

* Longer landing roll
* More variation in speed due less drag
* Engines less responsive as lower thrust setting
* Easier to carry excess speed into the flare
* More energy into the brakes
* Tailstrike more likely in some types

Advantages of higher flap setting:

* Shorter landing roll
* More stable airspeed
* Engines more responsive
* Lower pitch attitude
* More time to adjust flightpath
* Minimises brake temperatures

Disadvantages:

* May need more control application
* Often close to limit/relief speeds in turbulence
* Loss of airspeed in the flare may need prompt action
* Less fuel efficient

If I was landing on a long-ish runway with a headwind component, I'd probably go for the lower flap setting. A wet and/or shorter runway, tail wind, high landing weight and/or high density altitude would have me fully configured. The books usually say I could land with either but I have a strange aversion to planning the use of a large percentage of the available runway if there is an option to use less...

[bubbers44]

FW, I agree with your analysis. We all have found what works for us and are comfortable and successful using that technique. Why change it because some other pilot finds a different way of doing it works better for him?

[JammedStab]

Nice post FullWings.

Thought I might add one.

On some aircraft, less flap can mean more difficulty slowing to approach speed while maintaining minimum approach thrust. On the 727-200 with a Raisbeck hushkit and a maximum of Flaps 28, at light weights it was difficult to slow down to approach speed at minimum EPR.

[777fly]

Its been an interesting journey through this thread with some amazing drift off topic, good to see that it's back on track. BARKINGMAD made the best observation some time back. In turbulence and limiting crosswinds its an advantage to reduce flap, where permitted, because the spanwise lift distribution moves outboard and increases roll response. The reduced drag also improves speed recovery in gusts. Try landing at flap 30 in a B777 in turbulence and a circa 40kt crosswind and you can reach full roll input at times. Flap 25 makes it much easier to manage.

[Emoclew]

I fly the A320 and always use Conf 3 rather than Conf Full in gusty/crosswind conditions, primarily for better controllability.
From what what I have read, Conf Full on Airbus uses a lot of spoiler deflection for roll control, and the response of spoiler deflection is not linear ( unlike aileron deflection ) leading to overcontrolling and PIO.
For myself, Conf 3 with more "normal" aileron response makes the 320 fly like my previous non-FBW types, and makes the gust corrections much easier.
I am not a test pilot, so if another explanation is correct, I would be happy to stand corrected.

[Vaneev]

I think that the main advantage of lower flap setting for approach in gusty/ crosswind is slower reaction aircraft on changing in sideslip.
In gusty wind sideslip is continuously fluctuating and aircraft is continuously banking from side to side due to static lateral stability.
(see http://aviacom.ucoz.ru/Book_13_Principles_of_Flight.pdf, Chapter10, page 302)
All contemporary aircrafts have swept wing and this lead to excessive static lateral stability (see pages 306, 307 and figure 10.62).
The more Cl (coefficient of lift) we have - the more "dihedral effect" we have, and we have to counter the more sharp lateral aircraft movements.