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AirPacific747
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Airbus A320 FBW Problem?

Wed Oct 30, 2013 11:03 pm

I am an Airbus driver and I have noticed that during approach if there is a lot of gusting wind, the flight controls have a tendency to feel sluggish. For example today on final approach fully configured at approximately 100 feet agl, there was a sudden gust from one side, so I tried to counter this gust by giving full sidestick deflection into the wind and there was almost no reaction from the aircraft.

Another problem I've noticed is that during challenging weather conditions on an approach, some pilots (myself included) have a tendency to fly it as if it was a conventional aircraft by trying to counter the gusts too much which will only make the situation worse. A captain told me that this is called pilot induced oscillations. Is this a well known phenomenon with FBW aircraft?

I've talked to a few of my colleagues and a few experienced captains that have flown both the 737 and the A320 and they tend to agree with me. The pilots who have flown both types think that in many ways the A320 is superior, but when it comes to handling during adverse weather conditions, the Boeing is the winner.

[Edited 2013-10-30 16:08:10]
 
PGNCS
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RE: Airbus A320 FBW Problem?

Wed Oct 30, 2013 11:25 pm

Quoting AirPacific747 (Thread starter):
For example today on final approach fully configured at approximately 100 feet agl, there was a sudden gust from one side, so I tried to counter this gust by giving full sidestick deflection into the wind and there was almost no reaction from the aircraft.

I first checked out on the 320 in 1995 and have not ever seen this. This isn't to say the aircraft handles purely like a conventional aircraft.

Quoting AirPacific747 (Thread starter):
The pilots who have flown both types think that in many ways the A320 is superior, but when it comes to handling during adverse weather conditions, the Boeing is the winner.

I have flown both extensively and strongly disagree with that assessment.
 
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zeke
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RE: Airbus A320 FBW Problem?

Thu Oct 31, 2013 1:31 am

Quoting AirPacific747 (Thread starter):

Basic flying 101 should tell you controls are less responsive at lower airspeeds on any type.

Sounds like you are a relative new comer to swept wing aircraft and airliners in general. You will need time to develop your skills on type. I cannot say I however needed full sidestick at 100 ft, and that is landing in gusting winds with 40 kts crosswind.

PIO is not restricted to FBW aircraft, happens even on a little C150. I am sure someone along your training would have told you set, check, hold, adjust, trim. PIOs often come from pilots not knowing their "targets" (pitch/N1) then need in a situation, and then "hunt" for the target by looking at the resulting performance. If you know the pitch attitude, and N1 for an approach, set those the performance will follow, you will only need very small changes to maintain the correct path, even in gusting conditions.

If you think the aircraft is not stable by your company SOPs, go around....
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PhilBy
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RE: Airbus A320 FBW Problem?

Thu Oct 31, 2013 7:13 am

Quoting AirPacific747 (Thread starter):
A captain told me that this is called pilot induced oscillations. Is this a well known phenomenon with FBW aircraft?

Normally the control laws on FBW aircraft should act to damp out PIO compared to non-FBW aircraft.
The same phenomenon can also be found in cars and bikes.
 
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AirPacific747
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RE: Airbus A320 FBW Problem?

Thu Oct 31, 2013 9:45 am

Well I just asked a third captain today who also used to fly the 737 and he also have noticed this difference between the two aircraft. Maybe I am too inexperienced to have an opinion about this, but if three different captains at my base all share this opinion, then maybe there is something to it?
 
PGNCS
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RE: Airbus A320 FBW Problem?

Fri Nov 01, 2013 2:16 am

Neither zeke or I are trying to say the two aircraft handle identically, but your assertion that the A-320 series is somehow worse or lacks control authority is simply incorrect. Like zeke, I have also never needed full sidestick displacement in any crosswind, nor have I detected abnormally slow control response in either aircraft.
 
Pihero
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RE: Airbus A320 FBW Problem?

Fri Nov 01, 2013 9:08 pm

Quoting AirPacific747 (Reply 4):
Maybe I am too inexperienced to have an opinion about this, but if three different captains at my base all share this opinion, then maybe there is something to it?

PGNCS and Zeke are right : You seldom would need full aileron defexion, even in ultra-bumpy conditions : What you and your fellow pilots are - IMHO - experiencing without understanding is the characteristics of the 'Bus FBW system. Here you'd have to consider two things :
1/- Normally, the aircraft will take care of any exterior disturbance, especially gust... In this case, the system would already have started countering the lifting wing...
2/- there is a time lag of between one and two seconds before the flight controls (ailerons and spoilers) reach your commanded full deflexion . Next time you perform a control check observe the lag on your control surface indicator.
The result of 1 and 2 is :
3/- if you need full deflexion, keep your stick there !
4/- ...but in all probability you'll end up fighting the system and entering the stupid PIO loop...
Just ride the turbulence and work with your aircraft, it's so much simpler and so much more comfortable to do so !!!
...and RELAX !!!
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Chaostheory
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RE: Airbus A320 FBW Problem?

Sat Nov 02, 2013 4:39 pm

Quoting Pihero (Reply 6):
4/- ...but in all probability you'll end up fighting the system and entering the stupid PIO loop...
Just ride the turbulence and work with your aircraft, it's so much simpler and so much more comfortable to do so !!!
...and RELAX !!!

  

As one of my colleagues would say, give the sidestick a "nudge" or a "flick" of the wrist. There's no need to wrestle with it.
 
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Starlionblue
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RE: Airbus A320 FBW Problem?

Sun Nov 03, 2013 1:32 am

Quoting Pihero (Reply 6):
4/- ...but in all probability you'll end up fighting the system and entering the stupid PIO loop...
Just ride the turbulence and work with your aircraft, it's so much simpler and so much more comfortable to do so !!!
...and RELAX !!!

I find it interesting that this is exactly the same advice I got when I was struggling with landings one fine afternoon in a 172. I hadn't flown in a few months and was inducing way more roll and pitch myself than the wind was through overcorrection. The instructor told me to relax and give the plane a bit of time. The next approach was much better.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
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AirPacific747
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RE: Airbus A320 FBW Problem?

Sun Nov 03, 2013 3:04 am

You guys are still ignoring the fact that I've asked a few captains now, also one who also flew the MD and the BAE avro and they all say the same. One of them has over 11.000 flight hours. Over 2000 of them on the Airbus, the rest on other types.
 
mandala499
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RE: Airbus A320 FBW Problem?

Sun Nov 03, 2013 4:02 am

Quoting AirPacific747 (Reply 9):
You guys are still ignoring the fact that I've asked a few captains now, also one who also flew the MD and the BAE avro and they all say the same. One of them has over 11.000 flight hours. Over 2000 of them on the Airbus, the rest on other types.

You also seem to still be ignoring the experience of Zeke, Pihero and PGNCS.
Zeke I am sure has over 11,000hrs experience and definitely a lot more than 2000hrs on the Bus FBW, and lots of experience on non-FBW jets.
Pihero I know for a fact has over 11,000hrs total of jet time, has 737, 747, L1011 and God knows what else on his experience... and he has a lot more than 2000hrs on the Airbus FBW, heck, he's an instructor (and examiner) on it (320)!
PGNCS has a lot of experience too (which I wouldn't be surprised if he has over 11,000hrs and over 2000hrs on the bus FBW).
These 3 folks don't always agree... but when they do, don't you think they're onto something too?

If that's not enough in your books, guess what? What they said, is exactly the same as the answers of the following I've asked in the past (that question of yours isn't a new one):
- A 320 captain with over 11,000hrs experience, with 737-200, 737-300 and A320 experience (and 4000hrs as PIC on 320)
- A 320 captain with over 15,000hrs, CAA inspector pilot in 2 nations, 320 instructor, 320 examiner, DFO of an airline, with experience of over 2000hrs each as PIC in 330/340, 320, 737-200, 737-Classics, F28, and still also checkride newbies on their PPL, CPL and IR exams.
- A 320 captain with over 11,000hrs experience including over 2000hrs PIC in A320, and PIC'ed 737-200, 737-300, and Twin-Otters.
- And so on... and so on...
And yes, each of them have landed a 320 and non Airbus FBW in near Typhoon conditions, and 30kt pure crosswind gusts (am also sure Zeke and Pihero have had a fair share of these in the Airbus FBW and non Airbus FBW too).

Just because they're right doesn't mean you're wrong and just because they're wrong doesn't mean you're right. Most of the time, the truth is inbetween.

And if you're new to the concept of PIO, by God, for the sake of your life I hope you listen to these 3 guys answering your "query" here.

Quoting Pihero (Reply 6):
What you and your fellow pilots are - IMHO - experiencing without understanding is the characteristics of the 'Bus FBW system.

Sad truth and harsh reality.
Some people get it, some people don't... irrespective of the aircraft type.

Quoting Pihero (Reply 6):
2/- there is a time lag of between one and two seconds before the flight controls (ailerons and spoilers) reach your commanded full deflexion .

Again, some people get it, some people don't. There's a lag between stick input and results depending on the situation... that's irrespective of the aircraft too. Those who get it, can use the lag to provide a damn smooth ride in not so smooth conditions. Those who don't, make the passengers hold on to the airsick back and tighten their seat belts further... Those in between, Just ride the turbulence and work with your aircraft, it's so much simpler and so much more comfortable to do so !!!
When losing situational awareness, pray Cumulus Granitus isn't nearby !
 
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AirPacific747
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RE: Airbus A320 FBW Problem?

Sun Nov 03, 2013 4:43 am

Quoting mandala499 (Reply 10):

But on the other hand you are completely ignoring these now 4 captains experiences (and several FOs) that I've already talked to about this? How come their experiences are not counting? And my own experience too.
 
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RE: Airbus A320 FBW Problem?

Sun Nov 03, 2013 5:44 am

It sounds like you may be "churning butter" with the stick. Remember that you're controlling a rate of roll and a load factor change in the axes of motion of the stick.

The only time I've ever ended up with full deflection was in full back stick in a severe windshear recovery. Be on top of the motion of the plane, but it sounds like you may be getting out of phase with your stick movement vice airplane momentum.

The plane is extremely accurate in control during gusting winds if you actuate the stick and rudder properly- in fact a joy to fly in those conditions. I've found it to be just as maneuverable and controllable in those conditions as its boeing counterparts.
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AirPacific747
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RE: Airbus A320 FBW Problem?

Sun Nov 03, 2013 6:07 am

Yes that may be that I have a tendency to do so. I am not perfect but I am expressing my opinion here on behalf of some very experienced pilots and it frustrates me that our experiences are being dismissed completely which is why I've asked several captains to see if I could find one who doesnt agree with the others and so far ive been unsuccessful at that.

[Edited 2013-11-02 23:10:39]
 
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AirPacific747
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RE: Airbus A320 FBW Problem?

Sun Nov 03, 2013 6:09 am

So it's opinion against opinion. I don't see why those guys hold the key to the ultimate truth when I know of several very experienced pilots with different opinions. We're not getting any further. End of discussion.
 
Pihero
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RE: Airbus A320 FBW Problem?

Sun Nov 03, 2013 9:04 am

Quoting AirPacific747 (Reply 14):
So it's opinion against opinion. I don't see why those guys hold the key to the ultimate truth when I know of several very experienced pilots with different opinions.

This subject goes a lot farther than just *opinions*.
It has a lot to do with former experience, training syllabii, and a little with a degree of - let's say - distrust of the 'Bus from former non-A drivers.
The truth lays in demonstrations : Next time you're on a sim training, have the TRI program gusty conditions, high x-winds during an ILS approach and first watch the A/P do it... then on another approach, fly manually until you're reasonably satisfied that you're on the beams... then let go of the stick : you'll discover that your airplane takes care of most of the weather-related disturbance without your intervention and your main job is about staying on the beams.
That sim might be an enlightening session.

Contrarily to what you're thinking, neither Zeke, PGNCS or I are flouting our *superior* skills : we have had the privilege of being trained by the first group of 'Bus instructors, those who got the skills right from the originators of the philosophy.
Unfortunately, as time passes and new airlines purchase the planes, that knowledge gets diluted and you have some new pilots still thinking in terms of cable-and-rod flight controls ( and, for Pete's sake, trim tabs on the DCs / MDs ! ).
My very humble advice is to forget them and instead try and understand how the FBW works ( see the sim above ) as this knowledge will lead to trust.
For the time being, that trust doesn't exist and safety is very much at stake.

(Just my two € cents )

Kind regards.

PS : There's an Airbus Drivers site. Read Eric Parks's notes and see that his advice is almost exactly what I wrote on my earlier posts.

[Edited 2013-11-03 01:32:36]

[Edited 2013-11-03 01:35:01]
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airmagnac
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RE: Airbus A320 FBW Problem?

Sun Nov 03, 2013 9:08 am

Quoting AirPacific747 (Reply 14):
So it's opinion against opinion. I don't see why those guys hold the key to the ultimate truth when I know of several very experienced pilots with different opinions

Not quite sure what you were expecting with this thread then. You asked a question, and the 3 most qualified people on this site have given you similar answers, based on their own solid experience, yet you refuse to accept it.

As for the opinions of your colleagues, I don't think anyone is dismissing them per se, for the good reason that nobody here knows them, nobody knows exactly what you asked them, nobody here knows exactly what they answered, and nobody here knows exactly how you heard, understood and memorized those answers.
You may get a different answer if you ask "does the 737 have better handling in bad weather than the A320?" versus "does the A320 have worse handling in bad weather than the 737 ?" (see here).
Same if you ask "is the A320 prone to PIO ?" versus "are FBW aircraft like the A320 more prone to PIO, compared to classic designs like the 737 ?". (see here)
And if you were expecting to hear that the 737 handles better in bad weather, based on your experiences, then that is probably what you understood, whether or not that is actually what the captains said (see here). The fact that you titled the thread "A320 FBW problem" rather then something more neutral like "A320 handling in bad weather ?" already gives an indication about your prior inclination.

Granted this psychology stuff is moving away from pure design engineering, but these things are interesting for CRM and cockpit design  . Anyway, the point is that there's nothing anyone here can do with those answers that you report.
Up to you to decide which description of reality you want to use : your own, that of your colleagues or what was answered here. It seems you already have. But regardless, please watch out for PIO, be it on a 737 or an A320.  
My goal as an engineer is to fill my soul with coffee and become immortal
 
mandala499
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RE: Airbus A320 FBW Problem?

Sun Nov 03, 2013 4:00 pm

Quoting AirPacific747 (Reply 11):
How come their experiences are not counting?

When you got 2 equally experienced sides to the argument... which one do you go for?
And no, I didn't discount your side, as I said:

Quoting mandala499 (Reply 10):
Most of the time, the truth is inbetween.

Airmagnac got it spot on...
---

Quoting Pihero (Reply 15):
It has a lot to do with former experience, training syllabii, and a little with a degree of - let's say - distrust of the 'Bus from former non-A drivers.

Training sylabii is a BIG factor...    It's not about good or bad the training, but it's how the message gets conveyed.
When losing situational awareness, pray Cumulus Granitus isn't nearby !
 
prebennorholm
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RE: Airbus A320 FBW Problem?

Mon Nov 04, 2013 2:45 am

I have read this thread with great interest. First of all, I am not a 320 driver, and will for certain never be one. But there are a few things which puzzles me.

How can a 320 driver be "surprised" by gusts and roll control action in the air? Hasn't he performed dozens of landings in the sim with extreme gusts from all directions long time before his license gets stamped with the 320-stamp?

The gust came from the side. Only by analyzing the FDR can it be determined if it was actually from 3 or 9 o'clock. Was it from 4 or 8 o'clock? In the latter case it erodes air speed, and roll control becomes more sluggish on A320, B737 as well as C150.

How heavy were the wings - how much fuel left? The lighter the wings, the better the roll response.

The 320 has drooped ailerons in landing configuration, the 737 has not. The aileron opposite the side, from where the gust came, is going further down. Was the alpha on the high side, and aileron drooped? Then going further down doesn't do much except increase the drag.

If 30 years ago I was an Airbus FBW software developer (which I certainly wasn't), then I would have looked into letting the control software analyse the combination of alpha, droop and roll control stick input, and limit the down movement of the one aileron in order to reduce adverse yaw and to avoid any possibility of tip stall. I would guess that they did just that - and a few more things which I am unable to imagine.

On a non-FBW aircraft such intelligent control isn't possible, and for instance tip stall will be avoided by building the wing with more wash-out twist than optimal performance wise. In any case the regulators will ensure that planes have sufficient roll control. But two wings with different wash-out twist, and therefore different control surface geometri will for certain have different handling characteristics, especially at low speed. Pilots are paid to learn exactly how their plane handles.

But then, if Vref is kept rather precisely, then there shouldn't be much of a problem. Again it would be nice to have the FDR data and watch how the IAS developed during the gusty approach, otherwise I guess that this thread can continue beyond this century with various conflicting oppinions.

When a pilot, who brings me around in the world, experiences a "surprise" related to how his plane reacts, then I would be very happy if he goes to his sim and simulates the circumstances as good as he can - to learn not to get "surprised" next time. As a passenger I prefer that very much over putting the blame on what aircraft designers and regulators did right or wrong 25 or 30 years ago, and have been too lazy to correct during that time span.
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KC135Hydraulics
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RE: Airbus A320 FBW Problem?

Tue Nov 05, 2013 7:33 am

I find it hard to believe that the thread starter, supposedly being being a commercial pilot, is unfamiliar with PIO. I am starting to question some credentials, here, and wonder if this is a legitimate question.
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rheinwaldner
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RE: Airbus A320 FBW Problem?

Wed Nov 06, 2013 12:13 pm

Quoting AirPacific747 (Thread starter):
A captain told me that this is called pilot induced oscillations. Is this a well known phenomenon with FBW aircraft?

What training did you have where you have never heard about pilot induced oscillations? I would expect pilots at the controls of an actual aircraft to be instructed not only about well known phenomenons but even about the tricky ones.
 
jollo
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RE: Airbus A320 FBW Problem?

Wed Nov 06, 2013 3:57 pm

Quoting AirPacific747 (Thread starter):
I am an Airbus driver
...
A captain told me that this is called pilot induced oscillations. Is this a well known phenomenon with FBW aircraft?

Aw, c'mon! I am a lowly glider pilot, and the concept of PIO has been carefully hammered in my head well before getting my license (before I was first allowed to handle a tow, actually).
 
Maverick623
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RE: Airbus A320 FBW Problem?

Wed Nov 06, 2013 7:50 pm

Quoting AirPacific747 (Thread starter):

Another problem I've noticed is that during challenging weather conditions on an approach, some pilots (myself included) have a tendency to fly it as if it was a conventional aircraft by trying to counter the gusts too much which will only make the situation worse. A captain told me that this is called pilot induced oscillations. Is this a well known phenomenon with FBW aircraft?

I'd like to know which airline you work for so I can report their flight training department to the local authorities, as it is clearly inadequate.

I first learned about PIO in the first month of my PPL flight training, and it's been a big topic in every single checkride I've ever taken.
"PHX is Phoenix, PDX is the other city" -777Way
 
travelavnut
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RE: Airbus A320 FBW Problem?

Thu Nov 07, 2013 9:53 am

Quoting jollo (Reply 21):
Aw, c'mon! I am a lowly glider pilot, and the concept of PIO has been carefully hammered in my head well before getting my license (before I was first allowed to handle a tow, actually).

Yep same here, quite incredible an airline pilot wouldn't be aware of PIO.

Makes me wonder.....;

Quoting KC135Hydraulics (Reply 19):
I am starting to question some credentials
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Nicoeddf
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RE: Airbus A320 FBW Problem?

Thu Nov 07, 2013 4:52 pm

Honestly...this thread scares me. Really...
 
Pihero
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RE: Airbus A320 FBW Problem?

Thu Nov 07, 2013 5:26 pm

Quoting nicoeddf (Reply 24):
this thread scares me

Why ?
It is just sad that someone could breach the unspoken agreement on honesty of one's comments and experience in this forum for his own agenda and betray the trust of its members.
Will be more careful in the future.
Contrail designer
 
Nicoeddf
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RE: Airbus A320 FBW Problem?

Fri Nov 08, 2013 9:46 am

Quoting Pihero (Reply 25):
Why ?

Should have made at least one smiley and/or explain myself better.
I just read this thread with a lot of disbelief, shaking my head on the claims made by a pilot.

And for a second I imagined its 'real' that one sits up front asking questions about his airplanes behaviour with all (?!) of his fellow companies pilots agreeing with him, just to make a point.

And for this second, the thought scared me a bit in the role as a passenger only on large jets.  
Quoting Pihero (Reply 25):
It is just sad that someone could breach the unspoken agreement on honesty of one's comments and experience in this forum for his own agenda and betray the trust of its members.
Will be more careful in the future.

For sure it is.
 
astuteman
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RE: Airbus A320 FBW Problem?

Mon Nov 11, 2013 6:50 pm

Quoting airmagnac (Reply 16):
The fact that you titled the thread "A320 FBW problem" rather then something more neutral like "A320 handling in bad weather ?" already gives an indication about your prior inclination.

I must admit that's where my head goes....

Quoting prebennorholm (Reply 18):
I have read this thread with great interest. First of all, I am not a 320 driver, and will for certain never be one. But there are a few things which puzzles me.

They puzzle me too. How ON EARTH can someone be "qualified to fly the A320" but ask a question like this......

Quoting AirPacific747 (Thread starter):
A captain told me that this is called pilot induced oscillations. Is this a well known phenomenon with FBW aircraft?

Most regular readers on here, including me will know what PIO is. "A captain told me?"   

Quoting KC135Hydraulics (Reply 19):
I find it hard to believe that the thread starter, supposedly being being a commercial pilot, is unfamiliar with PIO. I am starting to question some credentials, here, and wonder if this is a legitimate question.

  
It just begs this question. Which is really unfortunate if the poster is genuine...

Something doesn't feel quite right here, and it's nothing to do with FBW or not FBW..

Rgds
 
HT1000
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RE: Airbus A320 FBW Problem?

Mon Nov 25, 2013 11:41 am

Adverse weather- Severe Turbulence
Landing
Conf Full or 3 can be used
However Conf 3 provides more energy and less drag

(Extract from QRH)

Seb
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