Air Asia A320

[Serenity]

FTJR flies commercial airliners for a living.   I differ to him to be honest.

He hasn't really commented on the controls moving in different direction though, he was arguing yoke vs sidestick.

[FTJR]

He hasn't really commented on the controls moving in different direction though, he was arguing yoke vs sidestick.

Because the topic is about the Air Asia A320 crash, not the controls, the captain pulled a CB that should not have been pulled in flight, did it affect the flight controls yes, were they moving in different directions (in the AAsia crash) no,  and there was no input whatsoever for 9 seconds after things went wrong.

The computers average out the combined sidestick inputs, i.e someone pulls full up, the other pushes full down, the result is neutral. If you have a dual input, it tells you both with a light and aural warning. In this case it seems that a conflicting command was given "pull down" so the FO, who I believe was a French national (English not his first language?) may have been confused as to what he should have been doing, which would be really understandable as it was going very wrong, very quickly.

I was not arguing yoke vs sidestick, i was saying that argument was not applicable to the topic.  and I corrected one misconception.

If you want to discuss the flight control laws, im happy too, but open a new discussion.

Hi Karaya <S>

[pembquist]

Because the topic is about the Air Asia A320 crash, not the controls, the captain pulled a CB that should not have been pulled in flight, did it affect the flight controls yes, were they moving in different directions (in the AAsia crash) no,  and there was no input whatsoever for 9 seconds after things went wrong.

I started the topic and it is about both the airasia crash and about the controls. My curiosity is peaked based on among other things page 59 of the final accident report http://kemhubri.dephub.go.id/knkt/ntsc_aviation/aaic.htm

This clearly shows the captains side stick is in a 15 degree pitch and 14 degree roll position while the copilots stick is in -16 degrees pitch and -7 degrees roll.

I am not saying that having sticks not working like they do in piper cubs is the reason the plane crashed, (the pilots are supposed to know how to fly the plane in all modes after all,) but to me it seems inexplicable that you would put pilots in the position of having two floppy joysticks competing with each other in a moment of crisis. I am sure there are good reasons for the design but I haven't heard anyone explain what those reasons are and I would like to know because I am interested. Does anyone know why the decision was made, (because it was a decision,) to have unconnected, (mechanically or virtually,) flight controls? All I can think is that it is a way to have redundant control sticks as a jam in one will not affect the other.

[FTJR]

I started the topic and it is about both the airasia crash and about the controls. My curiosity is peaked based on among other things page 59 of the final accident report http://kemhubri.dephub.go.id/knkt/ntsc_aviation/aaic.htm

This clearly shows the captains side stick is in a 15 degree pitch and 14 degree roll position while the copilots stick is in -16 degrees pitch and -7 degrees roll.

I am not saying that having sticks not working like they do in piper cubs is the reason the plane crashed, (the pilots are supposed to know how to fly the plane in all modes after all,) but to me it seems inexplicable that you would put pilots in the position of having two floppy joysticks competing with each other in a moment of crisis. I am sure there are good reasons for the design but I haven't heard anyone explain what those reasons are and I would like to know because I am interested. Does anyone know why the decision was made, (because it was a decision,) to have unconnected, (mechanically or virtually,) flight controls? All I can think is that it is a way to have redundant control sticks as a jam in one will not affect the other.

Thanks,  let me look at your link, I have to go work for a few days so I wont have time to digest it straight away.

[WaffenVW]

I've read the report and I'm astounded that they call it a complex emergency situation. Is flying a plane manually a complex emergency situation? It is just one more case of morons failing at flying a perfectly flyable aircraft by deliberately causing a stall.

[NatCigg]

I've read the report and I'm astounded that they call it a complex emergency situation. Is flying a plane manually a complex emergency situation? It is just one more case of morons failing at flying a perfectly flyable aircraft by deliberately causing a stall.

ht always said full nose down and opposite rudder 

[Busher]

I started the topic and it is about both the airasia crash and about the controls. My curiosity is peaked based on among other things page 59 of the final accident report http://kemhubri.dephub.go.id/knkt/ntsc_aviation/aaic.htm

This clearly shows the captains side stick is in a 15 degree pitch and 14 degree roll position while the copilots stick is in -16 degrees pitch and -7 degrees roll.

I am not saying that having sticks not working like they do in piper cubs is the reason the plane crashed, (the pilots are supposed to know how to fly the plane in all modes after all,) but to me it seems inexplicable that you would put pilots in the position of having two floppy joysticks competing with each other in a moment of crisis. I am sure there are good reasons for the design but I haven't heard anyone explain what those reasons are and I would like to know because I am interested. Does anyone know why the decision was made, (because it was a decision,) to have unconnected, (mechanically or virtually,) flight controls? All I can think is that it is a way to have redundant control sticks as a jam in one will not affect the other.

Pardon me for interjecting. As a retired airline Captain, I'd like to point out that the control design of the airbus series has proven to be reliable and cost effective for all the airlines who chose them for their fleet. I have never been type endorsed on any of them even though my airline had many types - I preferred the competition. I will be very interested in FTJR's comments on the aircraft.

This strikes me clearly as a CRM failure accident. Airlines with a strong safety culture and ALPA spend countless dollars and hours developing a training a team approach to cockpit operations. Both pilots should be working to assure that the airplane is never placed in a situation where either of them needs to use exceptional "stick and rudder" skills to correct a problem. In any case, only the "pilot flying" should be manipulating the airplane while the "pilot monitoring" offers information to assist in a disciplined fashion.

Do not fault "fly by wire" design. It exists effectively not only in Airbus but Boeing as well (B777 and B787).

Two pilots fighting over the controls whether they be conventional or computerized is a recipe for disaster.

[pembquist]

Hey Busher:

Sure its a great system.

I said I'd believe it prevents more accidents than it "causes" (don't know how else to put it)

When did I fault fly by wire?

The cause of the accident is that a defective component lead the captain to pull a circuit breaker he wasn't supposed to which caused the FBW to enter alternate law instead of normal law, the copilot couldn't control the airplane under alternate law for some reason, (supposed to be in his wheelhouse I would think,) thus putting the airplane in an upset that the crew could not recover from.

I still think it is weird to have two controls that can be placed in opposition to each other. Here is how Airbus addresses the difficulty posed by independent controllers:

Sidestick priority logic
‐ When only one pilot operates the sidestick, it sends his control signals to the
computers.
‐ When the pilots move both side sticks simultaneously in the same or opposite
direction and neither takes priority, the system adds the signals of both pilots
algebraically. The total is limited to the signal that would result from the
maximum deflection of a single sidestick.
Note: In the event of simultaneous input on both sidesticks (2° deflection off the
neutral position in any direction) the two green SIDE STICK PRIORITY lights on
the glare shield come on and “DUAL INPUT” voice message is activated.
A pilot can deactivate the other stick and take full control by pressing and keeping
pressed his priority takeover pushbutton.
For latching the priority condition, it is recommended to press the takeover push
button for more than 40 s.
This allows the pilot to release his takeover push button without losing priority.
However, a pilot can at any time reactivate a deactivated stick by momentarily
pressing the takeover push button on either stick.
If both pilots press their takeover pushbuttons, the pilot that presses last gets
priority.
Note: If an autopilot is engaged, any action on a takeover pushbutton disengages it.
In a priority situation
‐ A red light comes on in front of the pilot whose stick is deactivated.
‐ A green light comes on in front of the pilot who has taken control, if the other
stick is not in the neutral position (to indicate a potential and unwanted control
demand).
Note: If the aircraft is on the ground and commencing its takeoff run and one stick is
deactivated, this triggers the takeoff “CONFIG” warning.

[Busher]

"The cause of the accident is that a defective component lead the captain to pull a circuit breaker he wasn't supposed to"

I say again.... It still strikes me as a CRM accident. Why would a pilot touch a CB in flight unless directed to do so by Emergency Checklist?

As to independent control systems.... is it even relevant if only one pilot should, in a properly managed cockpit, be manipulating the flight controls.

I am sorry but I cannot see fault in the equipment.

With respect Sir.

[Serenity]

"The cause of the accident is that a defective component lead the captain to pull a circuit breaker he wasn't supposed to"

I say again.... It still strikes me as a CRM accident. Why would a pilot touch a CB in flight unless directed to do so by Emergency Checklist?

As to independent control systems.... is it even relevant if only one pilot should, in a properly managed cockpit, be manipulating the flight controls.

I am sorry but I cannot see fault in the equipment.

With respect Sir.

We're not saying THIS INDIVIDUAL CRASH is caused ENTIRELY by the sticks not being linked. What IS being posed is this: There seems to be ZERO good arguments for NOT linking the controls. There are MANY good arguments for linking them. Thus, as has been asked many times, is there any apparent logic to NOT having controls linked?

Yes, THIS incident was CRM. Yes, you can trace almost every airliner crash down to CRM, and CRM COULD have saved the situation. That being said, while CRM is the root cause, you cannot deny that these sticks being in conflicting positions indicates that perhaps had the sticks been linked, lacking non-verbal communication, the tactile feedback of the stick may have aided in the situation.

So again, this individual incident aside, what is the possible logic behind not linking the sticks?

(If that came off as disrespectful, I'm sorry, but it feels like pembquist and I are talking to brick walls. Everyone is quick to answer the question we're NOT asking.)

[Busher]

No offense or disrespect at all gentlemen. If the question is as basic as to why Airbus does what it does, I cannot comment. It has always struck me that their vision of flight control could lead to computer techs operating airliners with no "basic operating skills" (a United Airlines term) required.

I never wanted to fly one

<S>

[Serenity]

No offense or disrespect at all gentlemen. If the question is as basic as to why Airbus does what it does, I cannot comment. It has always struck me that their vision of flight control could lead to computer techs operating airliners with no "basic operating skills" (a United Airlines term) required.

I never wanted to fly one

<S>

Thank you. THAT'S what's driving me nuts. I don't think it caused the crash, but from experience, I've seen a LOT of value in linked controls, and nothing to be gained by controls which aren't linked.

[pembquist]

No offense or disrespect at all gentlemen. If the question is as basic as to why Airbus does what it does, I cannot comment. It has always struck me that their vision of flight control could lead to computer techs operating airliners with no "basic operating skills" (a United Airlines term) required.

I never wanted to fly one

<S>

No offense taken or intended. Untill I hear otherwise I am going to assume that Airbus viewed the chance of an incapicitated pilot or mechanical issue causing a jam on one stick as more likely than a failure of CRM and so made the sticks independent of each other. Then to address the obvious chance of conflict they came up with warning lights and signals and a slightly complicated takeover button. It seems counter intuitive but perhaps the thinking is that you are trading away an extremely dangerous single point failure (jamming of pitch and roll control) in exchange for a failure mode that requires multiple failures (not in normal law, breakdown of crm, flight skills for the law and conditions inadequate,) to become dangerous. I don't know but I'd like to understand the reason.

This reminds me of Abraham Wald, a Boffin during WW2 who made the statistical argument that can be described in a simplified way as: Don't add armor to airplanes in the places that returning airplanes have bullet holes add it in the places that don't have bullet holes because thats probably where the bullet holes were in the airplanes that didn't return.

 https://en.wikipedia.org/wiki/Abraham_Wald

[WaffenVW]

What I gather from Airbus is that they're trying to remove the 'human component' as much as possible, because it is by far the one system component that causes the most accidents. In this case the machine was flying the plane, but something broke and the machine didn't know what to do with it. So it handed the plane and 162 lives over to two humans, who promptly crashed it by doing insane and illogical things, as humans are prone to do.

[earl1937]

That crash had nothing to do with the Fly by wire system, it was a pilot error and did not occur as you describe it. https://en.wikipedia.org/wiki/Air_France_Flight_296
If something it was a false belief that the FBW system would save them from anything, it did prevent them from stalling but they had no speed to climb since they were in a near stall position.

Like it or not: FRW and computers have made commercial aviation a lot safer, it cannot eliminate all risks but it helps the pilots to avoid most of the common mistakes. If pilots had to fly manually they would be better pilots for sure, but they would also crash a lot more often. We cannot have commercial jets flying with a compass and a clock just because it was the way it was done in the past. Commercial aviation is about moving people and stuff from A to B in the safest and most efficient way. If you want to experience the freedom flying can give you then General aviation is there for you. I prefer to fly that way but just because I do it doesnt mean that i want the guys in the airliner im riding with to do the same.

Sorry "Charlie" (the tuna), but you are wrong sir! The crash I am referring to is this one:

https://www.youtube.com/watch?v=-kHa3WNerjU

The crew had taken off and after it assumed the VR attitude, the aircraft gained about 50 feet AGL, and proceeded to fly directly into a forest of trees dead ahead and all they would have had to do was knock off the computer and push the thrust levers full up and the crash would have been canceled!
The computer "screwed" up and that is my point about FBW, I know that is the way we are going in the future and someday, they will be completely trust worthy, but don't think we are to that point yet!
I called that friend of mine this afternoon, who now is a captain on a MD88 and he told me that which ever "stick" moved first, had priority, but the captain could always "over ride" the first officers "stick". It normally stayed in the neutral position unless the captain over rode it. I am referring to the first officer having command of the flight controls!
I know that I am old fashioned I guess, but like I said in another post, I have never heard of an aircraft crashing due to flight controls becoming in active of their own accord, I am referring to cable and push rod flight control actuators. 
Another case in point was the crash off Long Island, where the co-pilots input on the rudder was so much, he broke off the vertical stabilizer and of course, down they came. (I know someone in here argued that you could fly with out a vertical stabilizer, but that is BS, you can't, not with a standard tail arrangement) There are aircraft which can fly without a vertical stab, but that is a all together different flight control system!