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-   -   Airbus trepidation... convince me otherwise! (https://www.pprune.org/tech-log/473490-airbus-trepidation-convince-me-otherwise.html)

aa73 6th Jan 2012 13:39

Airbus trepidation... convince me otherwise!
 
Airbus trepidation... convince me otherwise!
OK Folks this question has been a long time coming. I know I'm gonna hear a lot of good and bad from both camps... that's fine.

With the A319 only 1.5 years away from arriving here at AA, I'm trying to erase a long running hesitation in someday flying this bird. For years I strongly disliked the Airbus cockpit philosophy and was rather glad that AA chose to stay true to Boeing.

I've had the opportunity to j/s on United and USAir Airbus cockpits and I must say..... I'm still hesitant.

There is no doubt in my mind that this is one of the most comfy cockpits I have ever sat in. The ergonomics are spectacular. Everything flows nicely.

But... I still question: Are the pilots REALLY in control? I had a lot of difficulty watching the engine instruments register changes without the throttles moving. I never quite knew what the engines were doing. Why are the throttles locked at Climb Thrust with the engines back at idle? This stuff really conflicts with my "Boeing-warped" mind.

I also had a tough time comparing aircraft pitch/roll commands without seeing a corresponding stick movement. Why, because the other stick doesn't move. How does the other pilot know what the flying pilot is doing?

Lastly: I understand that the stick commands a RATE, not simply a control surface movement. So if you bang in left stick and center it, the aircraft will continue rolling left until you bang in right stick. VERY disconcerting to me: I expect that, if you bang in left stick and center it, the aircraft would stop rolling, not increase it.

As I understand it, the 777, while still FBW, maintained the Boeing philosophy of keeping it a pilot's airplane.

As you can see, I have serious issues with this philosophy, not to mention the fact that this "pilot out of the loop" philosophy may have contributed to the lack of SA exhibited with Air France 447. I want to feel comfortable with the Airbus as this aircraft may very well be my first CA upgrade at AA. Please give me the pros and cons and help convince me that this aircraft will not "go computer psycho" without anything I can do about it.

Posted on APC and FI.com as well.

Thanks for any responses.
73

NOLAND3 6th Jan 2012 13:46

Just to clarify - when you apply left stick you are commanding a roll rate. As soon as you centre the stick the FBW will attempt to hold that bank.

Regards

C212-100 6th Jan 2012 13:54

There is no such thing as "banging the stick left, center it and the a/c continuing on the roll". What the bus do, and it works wonderfully once you fully understand the "how" is that once you reach the bank angle you commanded it will "autotrim" to keep that bank angle and fly it.

TTex600 6th Jan 2012 13:57

aa73, to my knowledge in over 20 years of operation, no FBW Airbus (AF447 could be argued) has fallen out of the sky because the FBW failed. That's a nice thing to dwell on.

In general, the biggest difference between the computer flown bus and the human brain flown McBoeing is pitch trim. The Bus auto trims and it does not trim for speed. Other than that, and here comes a BIG IF, IF the automation is all operable, the airplane pretty much flies like any other transport category swept wing jet. You want to turn left, you deflect SS left until you get the bank you want and let off, it just stays where you put it. Steep turns are easy as pie. Pitch appears at first glance to be normal, if you want to raise the nose, pull back and the nose comes up.
You will find that the SS and the FBW take about a hour on your first sim session to get used to and after that you will only think about it when you start reading AF447 threads. :eek:

aa73 6th Jan 2012 13:59

Thanks for the correction regarding roll rate.

But why does Airbus "auto-trim"? As a pilot I **WANT** to trim out the forces myself - so that I am in concert with what I want the airplane to do. When I put my 757 in a bank, I trim slightly nose up and it's exactly how I've flown for 20+ years.

I don't **WANT** autotrim, as it removes me from control that much more. I want to know where my trim is at all times. Is there any way to disconnect the autotrim and keep 100% "hands on" operation?

edit: in response to TTex: understood about the FBW not failing in AF447. But - and this is a big but - do you Airbus folks believe that the lack of "cues" (sticks not moving together, throttles not moving) contributed to the lack of the pilots' SA?

FatFlyer 6th Jan 2012 14:55

Hi,
The way to disable autotrim would be to turn off a few flight control computers and put the aircraft in direct law .The message USE MAN PITCH TRIM would appear on PFD and you would use the trim wheel. There is no artificial feel on the stick so it is difficult to fly smoothly (in the sim, never tried it for real) in direct law. This is not an approved procedure, flying in direct law is only ever done as as abnormal procedure.
The lack of thrust lever movement can lead to lack of awareness, if you get behind the plane, it can get a bit confusing. AB say, always know your FMA, this way you should have an idea what the plane is doing. AB also say that you have the option to disconnect and fly like a conventional plane though, as lots of us don't practise this enough, it sometimes causes more problems.
After a few years on the 73, I would say, the bus is generally has less work load and is more comfortable and takes care of pilots errors more. When it goes wrong though, it can get quite complicated, eg the BMI A321 which had a generator problem leading to flickering screens, uncommanded rudder trim, and caused the plane to turn and go 10 miles off course while the poor crew try to work out what is going on. Have fun

fantom 6th Jan 2012 15:20

OK, excluding my mil (very) fast types, and having only flown the 320; 321 and 330, and having only forty-two years' experience and having been an examiner on Airbus types for only the last twenty years or so, I can tell you it was the best flying in civil aircraft I had.

Pure magic; wait and see.

Post a notice here when you agree...waiting.

f

extreme P 6th Jan 2012 15:28

Do the course and see for yourself what the 'bus is all about.

Used to be the non-Airbus guys and gals knew all the reasons why the 'bus was substandard but after some time on type the tune usually changes.

The 777 has auotrim now as well so that is something you have to get used to in the future.

Wizofoz 6th Jan 2012 17:55


The 777 has auotrim now as well so that is something you have to get used to in the future.
No, it doesn't.

That being said, I have never flown an Airbus, don't care to as I'm to old to learn BUT- know plenty of guys who do and are perfectly happy doing so.

Honestly, differences in the flight controls are a minuscule fraction of what it means to be a pilot.

You are responsible for safely conducting the flight and putting the aircraft where it needs to be, in one piece with everyone breathing.

The Airbi do this JUST as well as the Boeing's, even if by a different philosophy re flight controls.

Go for it, enjoy the table (yeah, I DO wish I had one) and get used to the differences in FBW architecture.

Oh- and cash the paycheck and go home!!

macdo 6th Jan 2012 18:01

Sooooo much better than anything else! Would never want to go back now.

TTex600 6th Jan 2012 18:15


Originally Posted by aa73
Thanks for the correction regarding roll rate.

But why does Airbus "auto-trim"? As a pilot I **WANT** to trim out the forces myself - so that I am in concert with what I want the airplane to do. When I put my 757 in a bank, I trim slightly nose up and it's exactly how I've flown for 20+ years.

I don't **WANT** autotrim, as it removes me from control that much more. I want to know where my trim is at all times. Is there any way to disconnect the autotrim and keep 100% "hands on" operation?

edit: in response to TTex: understood about the FBW not failing in AF447. But - and this is a big but - do you Airbus folks believe that the lack of "cues" (sticks not moving together, throttles not moving) contributed to the lack of the pilots' SA?

aa, This site has a large number of engineers/programmers/techies who can tell you why it autotrims. I only know that it does. I agree, I want an airplane to stay on trim speed when I put it there, I hate having to chase airspeed when hand flying.

You can not disconnect auto trim, and contrary to the flight manual, you can't trim like a normal aircraft. Even if you attempt to manually trim, the system will fight you and remove your input as soon as you release the trim wheel. This is because the trim trims for "g" and for flightpath, unless you train your brain to trim for flightpath or "g", you will never get it in trim.

The AF447 discussion has about a million responses on at least seven threads, so I'll let you dig through them regarding the FBW failing. FWIW, my opinion on AF447 is this: everything contributed to the accident. In no particular order, I think poor training and procedures (based upon some utopian claim that the airbus flys like any other airplane), combined with auto trim that trimmed nose up well past the stall angle of attack, combined with the FP's limited experience (outside of the AB world and in manual flight), combined with the PM's lack of CRM, combined with bad pitot tubes, combined with flat glass/tape style displays, combined with non-linked SS's, all caused the accident. Oh yeah, had the crew been trained in cruise level Unreliable Air Speed drills, or how to properly take the controls, they would likely be drinking wine on the beach at Rio today.

For your future line flying, many of us have developed our own personal procedure for indication anomalies at cruise. It goes something like this.....ANY possible discrepancy of A/S, etc, leads to A/P off, Auto Thrust off, Flight Directors OFF, set 80% N1 and hold 2.5 degrees nose up and ignore all else until you are absolutely certain that you have it under complete control. You have to trust something, attitude and power are the most reliable instruments so we go with them.

extreme P 6th Jan 2012 18:16

Hey Wiz, have you ever noticed that bank angles up to 30 degrees do not require back pressure on the 777? Can you explain how that works?

"PFC's automatically control pitch to maintain a relatively constant flight path".

Is auto trim by any other name still as sweet?

Wizofoz 6th Jan 2012 18:36

No, it is not auto trim.

In Normal Flight Control Mode the 777 is trimmed by means of the Stabilizer. That does not move in response to the turn bias system. The 777 has a speed trim system.

If you change the ATTITUDE of the Airbus, it trims for that attitude- THAT is an Autotrim system.

It is not an autotrim system by another name- it is quite simply not an autotrim system.

extreme P 6th Jan 2012 18:46

So to clarify, PFC's automatically positioning the elevator and stabilizer is not auto trim?

aa73 6th Jan 2012 19:11

Thanks for the replies to all... and yes I look forward to commending the Bus on this site once I start flying it!

Flytiger 6th Jan 2012 19:23

@Extreme P

777 has autotrim?

I was of the impression that Boeings only trim for speed, if that?

The problem OP is talking about is that the Buses fly counter-intuitively, and take away command authority in ways he isn't comfortable with. As a pilot I think what he is saying is that he wants the responsibility to actually command the inputs - even many of them - all of them - to the ship - because then he knows what he has or has not commanded.

AF447 has been a runaway story in the MSM about this, the genie isn't going back into the bottle. The public are interested (and wary?) of the Airbus voodoo, much like engineers, architects etc who use PCs are wary of the so called Apple Mac voodoo.

What's so special about Airbus, except it gives you less work (all possible detriments aside for the minute)?

A and C 6th Jan 2012 19:27

No need for trepidation the bus can be treated more or less like any other aircraft, most of the peope who have been bitten by the bus simply failed to disengage ALL the automatics and take full manual control of the aircraft.

If you want an easy life then as long as you fall in love with the FMC you will like the bus, what it won't do as well as the Boeing is ride turbulence or crosswinds.

I personally prefer the Boeing but this is just a matter of taste, others on this forum will no doubt disagree......but at the end of the day I prefer to be connected to the controls with a large steel cable rather than a bunch of wiggly amps !

FLEXPWR 6th Jan 2012 23:32

C212

A small correction, that Airbus FBW (at least the 320 series) does not maintain a bank angle, it maintains a zero roll-rate when stick is at neutral.

Only two years flying on it and it is beyond what I hoped for in ergonomics and systems. Of course some things could be improved, but the magic is, they do get improved! Fully upgradable airplane in my opinion.

Flex

extreme P 6th Jan 2012 23:50

Hey Flytiger,

The 777 trims for speed. My point is if you are manually flying the airplane and it automatically trims for your control inputs to produce a "maneuver" that is auto trim. In my mind no back pressure or trim input required for bank angles up to 30 degrees means auto trim. It also auto trims for gear and flap selections. I don't see the difference between auto trimming for attitude or speed. It's still auto trim.

TTex600 7th Jan 2012 00:11


Originally Posted by A and C
No need for trepidation the bus can be treated more or less like any other aircraft, most of the peope who have been bitten by the bus simply failed to disengage ALL the automatics and take full manual control of the aircraft.

If you want an easy life then as long as you fall in love with the FMC you will like the bus, what it won't do as well as the Boeing is ride turbulence or crosswinds.

I personally prefer the Boeing but this is just a matter of taste, others on this forum will no doubt disagree......but at the end of the day I prefer to be connected to the controls with a large steel cable rather than a bunch of wiggly amps !

How do you "take full manual control" of the stab trim?

Seriously, all of this "the bus can be treated more or less like any other aircraft" is getting old. It isn't any other aircraft and Airbus pilots need to recognize such. Not that it's bad, it isn't; in it's own way it works very well but it demands techniques not demanded by other aircraft and that fact needs to be both understood and trained for. Bad grammar, I know, sorry.


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