A320 Flight Controls

Henning said:
One mistake, > is Greater than, < is less than, that's it.
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Thanks a lot,

Please allow me to come to roll.
Your side-stick now commands a rate of roll.
How does rate of roll affect G load? When the rate of roll is not increasing/decreasing, the plane is at 1G?

Thanks
 
TheBusFlyer said:
Thanks a lot,

Please allow me to come to roll.
Your side-stick now commands a rate of roll.
How does rate of roll affect G load? When the rate of roll is not increasing/decreasing, the plane is at 1G?

Thanks
Click to expand...

Well, roll will have a G force component in the actual roll around longitudinal axis, with the wing tips seeng more force than the root, however this is an extremely small component that is not measured or generally considered.

The measured Gs come from the same addition to the vertical (through the plane, not earth) component of lift provided by the wing/tail combo constantly affecting and redirecting the inertial vector.

IOW, Rolling doesn't really affect G in and of itself. All it does is changes the vector of the Gs you induce with back stick. If you just roll and don't apply back stick, you will remain at 1G and lose altitude as you turn.
 
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Greg Bockelman said:
None of that had anything to do with fly by wire.
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Not sure about the Airbus into the ocean. who knows what the hell they were thinking if they were thinking at all. Perhaps the knowledge that "this airplane can't stall because the computer won't let it" was a contributing factor in their inability to recognize their stalled condition and recover? Id say there is a strong chance of that.

The Airbus that crashed into the trees on a demo low pass full of people was the result of the captain being comfortable with flying the airplane on the edge of the envelope at low altitude to demonstrate how the computer would keep the plane flying. Unfortunately in that case they disabled the computers ability to add thrust and by the time the flight crew realized they were out of energy and altitude they couldn't spin the engines up in time. The computer couldnt save them and it also couldn't move the trees or ground for them.

Those that are overly dependent on GPS can't navigate without it, those that are overly dependent on an autopilot can barely keep their plane right side up in IMC without it, perhaps those that are overly dependent on computer envelope protection can't protect the envelope themselves if the computer fails to do so?

I think that's the point Clark is trying to get at.

I like the idea of fly by wire and envelope protection but as someone who builds technology I would never claim I or anyone else could build such a solution that wouldn't have a failure mode that would make the existence of the FBW worse than not having it at all. I personally think the vast majority of flight crews are compentent enough to stay in the envelope if the computer can't but obviously there are a handful of examples of crews making rather basic airplane handling mistakes.

What we do about it? I have no idea. I'm not convinced we really need to do anything. I can't speak to what's covered in the sim for Airbus pilots but perhaps there's room for improvement there. Perhaps there isn't. Someone will always manage to figure out a way to crash.
 
AF 447 was an issue of having three disassociative reacting in the cockpit.
 
jesse said:
Not sure about the Airbus into the ocean. who knows what the hell they were thinking if they were thinking at all. Perhaps the knowledge that "this airplane can't stall because the computer won't let it" was a contributing factor in their inability to recognize their stalled condition and recover? Id say there is a strong chance of that.

The Airbus that crashed into the trees on a demo low pass full of people was the result of the captain being comfortable with flying the airplane on the edge of the envelope at low altitude to demonstrate how the computer would keep the plane flying. Unfortunately in that case they disabled the computers ability to add thrust and by the time the flight crew realized they were out of energy and altitude they couldn't spin the engines up in time. The computer couldnt save them and it also couldn't move the trees or ground for them.

Those that are overly dependent on GPS can't navigate without it, those that are overly dependent on an autopilot can barely keep their plane right side up in IMC without it, perhaps those that are overly dependent on computer envelope protection can't protect the envelope themselves if the computer fails to do so?

I think that's the point Clark is trying to get at.

I like the idea of fly by wire and envelope protection but as someone who builds technology I would never claim I or anyone else could build such a solution that wouldn't have a failure mode that would make the existence of the FBW worse than not having it at all. I personally think the vast majority of flight crews are compentent enough to stay in the envelope if the computer can't but obviously there are a handful of examples of crews making rather basic airplane handling mistakes.

What we do about it? I have no idea. I'm not convinced we really need to do anything. I can't speak to what's covered in the sim for Airbus pilots but perhaps there's room for improvement there. Perhaps there isn't. Someone will always manage to figure out a way to crash.
Click to expand...

Consider this: The airlines in the US operate Airbus products, and Boeing 777 and 787's, all FBW aircraft and highly automated. Now look at the accident rates on these airplanes as operated by US carriers. It's virtually nil.

Now look at Asian carriers and a few European carriers operating the same airframes and look at their records, not so good.

Drill down to the root cause of these accidents and incidents and you find a common thread, training and standards.

As an Expat that has flown with an Asian carrier I can attest to the lack of training and standardization. Another big factor for the Asian carriers is culture and the reluctance to accept CRM or any modern philosophies such as ADM or ARM.
 
Greg Bockelman said:
None of that had anything to do with fly by wire.
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Actually the SFO incident did. Autothrottle is just as much FBW as any part of the design. Failure to understand that is a failure in training and in system understanding.
 
Clark1961 said:
Autothrottle is just as much FBW as any part of the design.
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Not by any industry-accepted definition that I'm aware of, any more than the autopilot head in your panel makes your light piston single FBW. Regardless, failure to understand the operation and indications of a pilot relief mode and a fundamental breakdown in airmanship put that airplane into the ground. Whether or not it was FBW is irrelevant.

Nauga,
and his root-cause analysis
 
Singlepilot said:
No, in this scenario you are in a direct sidestick to flight control response between v alpha prot and v alpha max.

Above 1.25g the computers halt the auto trim function. 1.25g equates to 33 degrees of bank. The system is designed like this so that if you want to enter a normal turn you do not need to correct for the loss of the vertical component of lift as in a conventional plane. To turn you simply command the side stick left or right and the computers will adjust to maintain level flight. If you want to bank more than 33 degrees you will need to pitch up to maintain level flight just like in a conventional plane. The designers made it this way because a transport category aircraft should not "normally" need a bank angle exceeding 33 degrees. You can bank up to 67 degrees but they wanted to make you tactilely aware that you were doing so by needing to correct the pitch manually between 33 and 67 degrees.

The trim stops at V alpha prot for the same reason it's inhibitBed at low altitude. At slow speeds large amounts of trim are required to trim for neutral control response. Once you begin recovering and your airspeed starts rapidly increasing the trim rate lags the airspeed recovery and the aircraft is out of trim.


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Click to expand...

Thanks,

So could you please explain me this?

hen you turn full right (you want max rate of roll), you reach 1.25g?

Please explain,
TBF
 
TheBusFlyer said:
Thanks,

So could you please explain me this?

hen you turn full right (you want max rate of roll), you reach 1.25g?

Please explain,
TBF
Click to expand...

You're getting confused again, read what I wrote above. The ROLL has nothing to do with any G parameters, the G parameter is still in the back stick force controlling the elevator. Rolling does not turn the plane or add any significant Gs, even at the wing tips. It is introducing a horizontal component of lift to the equation, that detracts from the Vertical component of lift that requires the increase in total lift. Since you have to maintain this through the turn, you maintain the G load through the turn, otherwise you lose altitude.

Perhaps you may want to read the Pilot's Handbook of Aeronautical Knowledge (a free download from the FAA' website) and give that a good read through. From reading your threads and questions, it appears that you are trying to learn an A-320 without learning how to fly first. It's like starting school in college as 2nd grader, you lack the foundation information to make sense out of what you're reading. I suggest you back up, put down the A-320 book for a few days and read the PHAK to get that foundation information you appear to be lacking.
 
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jesse said:
Perhaps the knowledge that "this airplane can't stall because the computer won't let it" was a contributing factor in their inability to recognize their stalled condition and recover? Id say there is a strong chance of that.
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If operators are not training their pilots how to deal with typical and documented failure modes in their airplanes then there is a far more fundamental issue than the failure mode itself. If the pilots don't *understand* or retain the training on these failure modes then there is a different equally fundamental issue.

jesse said:
...I would never claim I or anyone else could build such a solution that wouldn't have a failure mode that would make the existence of the FBW worse than not having it at all.
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Then you probably won't be designing any FBW systems, at least man-rated ones. Most of my dealings with FBW are with airplanes that are *unflyable* without them. I can't do any worse than that. I know, I've tried. :rolleyes:

Nauga,
who is robust but sub-optimal
 
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nauga said:
Then you probably won't be designing any FBW systems, at least man-rated ones. Most of my dealings with FBW are with airplanes that are *unflyable* without them. I can't do any worse than that. I know, I've tried. :rolleyes:

Nauga,
who is robust but sub-optimal
Click to expand...
The point remains. The failure of the system is a possibility and in that case you'd be better off in an airplane that was stable enough to operate without it.

With that said - if that's an acceptable risk - then it's an acceptable risk. You can't prevent mistakes or accidents all you can do is minimize them.
 
jesse said:
The failure of the system is a possibility and in that case you'd be better off in an airplane that was stable enough to operate without it.
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That's not just "better off without the system", that's "better off in a different airplane." You might say the same thing if you're on fire. How many complete and total FBW system (including backups and reversionary modes) failures can you name and in what airplane? I have records, and I can't name one that wasn't preceeded by other equally catastrophic events that rendered the airplane unflyable.

In other words I don't think the complete failure you're worried about is even remotely likely. At least not on any system I'm familiar with.

Nauga,
who knows why MECH is gone
 
An interesting commonality in these threads about FBW are the ones who actually fly them don't have a problem with them, and most of those who have never flown one are against their concept.
 
RotorAndWing said:
An interesting commonality in these threads about FBW are the ones who actually fly them don't have a problem with them, and most of those who have never flown one are against their concept.
Click to expand...

Well, people better get over it, it's only going to become more prolific; it's not going away.
 
Henning said:
Well, people better get over it, it's only going to become more prolific; it's not going away.
Click to expand...

I have no problem with it and I do believe a good implementation will save more lives than it will kill. I also accept the reality that it's not a matter of if a failure in the system contributes to a death it's just a matter of when. I think a good system will save by far more than it will lose.
 
jesse said:
I have no problem with it and I do believe a good implementation will save more lives than it will kill. I also accept the reality that it's not a matter of if a failure in the system contributes to a death it's just a matter of when. I think a good system will save by far more than it will lose.
Click to expand...

I have no real problem with the systems the way they are laid out. I think R&W is right on the money with where the problems with the system lie, and they aren't in the planes.
 
Henning said:
I have no real problem with the systems the way they are laid out. I think R&W is right on the money with where the problems with the system lie, and they aren't in the planes.
Click to expand...

Agree. Although Boeing has a much different perspective on flight envelope protection and other such things in their FBW than Airbus. As a engineer, I don't know which one I like better...quite frankly don't have the technical data to really decide. As a pilot I think I prefer Boeing's setup. As a passenger I'll ride in the back of either of them.
 
jesse said:
Agree. Although Boeing has a much different perspective on flight envelope protection and other such things in their FBW than Airbus. As a engineer, I don't know which one I like better...quite frankly don't have the technical data to really decide. As a pilot I think I prefer Boeing's setup. As a passenger I'll ride in the back of either of them.
Click to expand...

I'm up in the air on it too between the Boeing and Airbus philosophies, I can see the pro and con arguments for both, and they are really pretty evenly matched. If you look at the logic on both, they produce the desired effect. I think a good pilot with proper systems understanding can make either do what they need. After the AF447 crash, I was superbly impressed at how perfectly the system managed the pilot commanded falling leaf stall for over 30,000' even in degraded condition. As a pilot I would have no hesitation flying one, much less as a passenger.
 
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TheBusFlyer said:
Thanks,



So could you please explain me this?



hen you turn full right (you want max rate of roll), you reach 1.25g?



Please explain,

TBF
Click to expand...


TBF,

Sorry, your thread has been hijacked. Perhaps you can revive it on APC with AF330 ;)

Full left and right sidestick command roll at 15 degrees per second up to 67 degrees angle of bank.


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No problem for APC! ;)

Ok, so roll has nothing to do with G!

On the first picture posted by R&W, it says that side-stick also demands an AoA.
Could you please explain that?

Thanks!
 
TheBusFlyer said:
No problem for APC! ;)

Ok, so roll has nothing to do with G!

On the first picture posted by R&W, it says that side-stick also demands an AoA.
Could you please explain that?

Thanks!
Click to expand...

What part of the explanation I gave wasn't clear? You have to add AoA to make up for the vertcal component of lift you switch to horizontal in a turn. If you don't add AoA, you lose altitude.
 
TBF,
I agree with Henning. You need a more basic understanding of the aerodynamics involved.


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The original question Dr. O presented was should airline pilots have to fly GA aircraft o demonstrate stick and rudder skills...

I think one only needs to compare the GA accident rates with the professionally flown aircraft/turbine accident rates to show that this is a ridiculous question.

I think a better questions is what can each pilot do to maintain proficiency as high as possible?

I for one disconnect the autopilot, auto thrust and deselect the FD guidance as often as possible and fly the aircraft with raw data to maintain my hand flying skills.

On top of this I have a thorough understanding of my aircraft's systems and know when I need to turn off the automation and also how to force the FBW system into alternate law if needed to isolate the computers in cases where they may be adversely affecting the safe outcome of the flight.

For the GA pilots, how often do you really practice abnormal and emergency procedures with a competent, professional instructor? Do you attend professional training at SimCom or some other professional training provider on a regular basis? Are you really as proficient as you should be?

I agree that airline pilots should be proficient in the more basic aspects of aircraft control but is a flight in a Baron really accomplishing that?

Perhaps a better suggestion would be to require abnormal maneuvering training in an aerobatic certified jet aircraft. Decompression chamber training should be required for pilots and crew members of all high altitude capable aircraft.

On the flip side perhaps we should require advanced simulator training once or twice a year for the GA pilots and CRM skills for the single pilot cockpit.

As an industry and profession why are pilots still going below minimums, flying in weather beyond our and our aircraft's abilities, having stall/spin accidents, landing gear up, and other avoidable accidents?

Those who live in glass houses shouldn't throw stones and we all need to do our part making aviation as safe as possible.






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Asian pilots...

Rotor and Wing understands. I have flown with these pilots as well. You really need to understand the culture and the differences in hiring and training.

Typically airlines recruit pilots right out of university or during their studies and then send these zero time pilots to the U.S. Or Australia to get their ratings but absolutely no real world experience. They have no idea how to fly in challenging weather conditions and rely instead on memorizing their FCOM's as a broken crutch.

I've done a simple go around in VFR weather due to spacing on final only to have the FO literally throw up his hands and mutter about getting in trouble with the company when they download the QAR data while I proceed to fly the aircraft single pilot with distractions.

It is a vastly different culture and you should experience it before you lump the extremely well trained and professional US airline pilot crew in with a large majority of the Asian crews.



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Automation...

Ahh, it goes both ways. I've seen pilots way too reliant on automation and I've seen pilots who had no idea how to use the automation in their airplane. You have to know how to use it and you have to know when to use it.

I flew once with a white collar professional in his turbine bonanza. He had no idea how to use the autopilot or flight director or how to program his GPS for an approach. His flying skills were sketchy at best and I suggested he get some instruction on how to use all the tools at his disposal. I asked him why he had his bonanza converted and his reply was, "Well, after the gear up accident I figured if I was replacing the engine and prop anyway I should get the turbine conversion." A few months later he crashed and killed himself and his family.

Ok, rants over. Fire at will...



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Yes, so when you roll, you lose altitude. To remain at LVL, you increase AoA (so G load).
When you complete roll, you are at the same altitude and G load is equal to 1.

I am *normally* right! ^^ :)

But I am not talking about roll. I am talking about the first picture posted by R&W (page 1). It says AoA demand THEN only Gload demand...

Is it AoA for roll?

Thanks
 
The diagram indicates that angle of attack protection has priority over all other modes.


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Thanks a lot SinglePilot,

So when AP/FD modes are flying the plane, they always remain between -0.5g & 1.3g?

Thanks
 
True, Henning. But that's been the focus of the discussion to date. Well, maybe focus is a bad word here...


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Yes! In normal law of course.

Do what is the G "range" the AP doesn't try to exceed?

Thanks
 
I honestly don't know. I didn't design the system and my manuals are not that specific. There are conditions where the autopilot will disconnect but exceeding g thresholds isn't one of them in my books.


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Clark1961 said:
Actually the SFO incident did. Autothrottle is just as much FBW as any part of the design. Failure to understand that is a failure in training and in system understanding.
Click to expand...



The auto throttle system has nothing to do with FBW. It's an automation system, not a FBW system.

If the 777 in SFO was a 757/767, the exact same thing would have happened and those two a/c aren't FBW.
 
Rex Kramer said:
The auto throttle system has nothing to do with FBW. It's an automation system, not a FBW system.

If the 777 in SFO was a 757/767, the exact same thing would have happened and those two a/c aren't FBW.
Click to expand...

Okay, control of thrust is not a flight control? I never knew that...(and still don't)
 
Clark1961 said:
Okay, control of thrust is not a flight control? I never knew that...(and still don't)
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Kind of confusing to me as well, but I can see where there would be a distinction once you reach the type rating level of training. They are flight controls, but I think technically, "FBW" only applies to 'flight surface controls', so while ancillary and connected, it isn't part of the FBW loop.
 
Henning said:
Kind of confusing to me as well, but I can see where there would be a distinction once you reach the type rating level of training. They are flight controls, but I think technically, "FBW" only applies to 'flight surface controls', so while ancillary and connected, it isn't part of the FBW loop.
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They're splitting hairs...is there any mechanical connection linking the throttles and the engines on these aircraft? I believe that previous threads have already settled the question for the Airbus.
 
Clark1961 said:
They're splitting hairs...is there any mechanical connection linking the throttles and the engines on these aircraft? I believe that previous threads have already settled the question for the Airbus.
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I agree it's splitting hairs, and I'm not sure that the argument really makes a difference, but I don't know the system well enough to see if there is a value or not to teaching it as a distinction due to making operating logic more clear. If it's required to prevent confusion, I can see why the distinction exists, other wise I'm with you, as I think most people not exposed to the systems are, if it is a piece of wire carrying electrons from the controls to the servos, it's all FBW.
 
Henning said:
I agree it's splitting hairs, and I'm not sure that the argument really makes a difference, but I don't know the system well enough to see if there is a value or not to teaching it as a distinction due to making operating logic more clear. If it's required to prevent confusion, I can see why the distinction exists, other wise I'm with you, as I think most people not exposed to the systems are, if it is a piece of wire carrying electrons from the controls to the servos, it's all FBW.
Click to expand...

There may be a bit more to it than that. I recall the comment on the 777 crash at SFO that when the aircraft was low the captain pulled the nose up and didn't add throttle because the airplane was supposed to do that for him. If that isn't FBW, I don't know what is. If someone wants to limit FBW to aerodynamic surfaces only then they are using a legacy definition and should adjust their mindset. I've long noted that many so called "experts" have a tough time with adjusting to progress.

This all ties back to the claim that flying a FBW aircraft around the pattern is no different than flying a Baron around the pattern. The claim of no difference is ludicrous as long as all the FBW functions and protections are in place. Just look at the difference in EP for a V1 engine loss...
 
Clark1961 said:
There may be a bit more to it than that. I recall the comment on the 777 crash at SFO that when the aircraft was low the captain pulled the nose up and didn't add throttle because the airplane was supposed to do that for him. If that isn't FBW, I don't know what is. If someone wants to limit FBW to aerodynamic surfaces only then they are using a legacy definition and should adjust their mindset. I've long noted that many so called "experts" have a tough time with adjusting to progress.

This all ties back to the claim that flying a FBW aircraft around the pattern is no different than flying a Baron around the pattern. The claim of no difference is ludicrous as long as all the FBW functions and protections are in place. Just look at the difference in EP for a V1 engine loss...
Click to expand...

:nonod: :rolleyes2:
 
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