Airbus sidesticks both active?

[buai stains]

My question is about the airbus FBW sidesticks. Can both be active, that is, be in control mode simultaneously. I cannot find a definite answer to this question. Under ordinary mechanical control only one pilot "has the aircraft" at one time. (Perhaps there is some "rubbering mode" for training that lets the captain make small corrections to the copilots control?)

Airbus literature states that the feed-back servos ensure that both sticks are always in the same position. This lets the non-control pilot feel what the other is doing.

I was watching a TV doco (4 Corners ABCTV) that claimed both sticks can be active, and that the flight computer averages the two instructions. I suspect that's nonsense.

Thanks.

[Double Hydco]

Airbus literature states that the feed-back servos ensure that both sticks are always in the same position. This lets the non-control pilot feel what the other is doing.


You have no idea what inputs the other pilot is making when in-flight.

If you both use the sidesticks simultaneously, you get a "Dual Input" aural warning.....

[Groundloop]

I was watching a TV doco (4 Corners ABCTV) that claimed both sticks can be active, and that the flight computer averages the two instructions. I suspect that's nonsense.

No, it is correct - but you do get the "Dual Input" warning. Quite common in the simulator to put both sticks fully in the opposite direction - nothing happens!

[buai stains]

Putting the sticks in opposite directions means the sticks are not in the same position. In the case of manual dual controls the sticks/wheels are chained together to ensure they are always synchronized. From the airbus literature I understand this is how their FBW sticks also work. The sticks are, however, also pressure sensitive. Is the "dual input warning" caused by pressure applied to the non-control stick.

To ask the question again; is there a setting/switch/button that makes only one stick the active one, or are both sticks always active?

[safelife]

There are no feed back servos. Neither aerodynamical forces nor the other sticks input is fed back to the stick.
Each stick is just spring loaded to center.
Inputs of either stick are added to each other.
There is a takeover button, once pressed the other stick is disabled.

[buai stains]

There is a previous thread here, with precise info:
http://www.pprune.org/tech-log/559226-a320-dual-input-side-stick-priority.html#post8929993

Dual inputs are indeed averaged when both sticks are active. (As a software engineer with 40yrs experience I can say this is a thoroughly stupid idea.)

The software cannot therefore be termed an Expert System as it does not mimic the manual controls of old.

No wonder there're so many mishaps when Airbuses are flown by less experienced pilots, or non-English/French speakers.

[Groundloop]

Putting the sticks in opposite directions means the sticks are not in the same position. In the case of manual dual controls the sticks/wheels are chained together to ensure they are always synchronized. From the airbus literature I understand this is how their FBW sticks also work.

Airbus sidesticks are NOT connected together.

[LlamaFarmer]

The sidesticks are two completely independent controls. They send an electrical signal based on the position they are in, and they add both the inputs together (up to the equivalent of full-deflection). So if both pilots make half-left inputs, the computer says that's full-left. If one puts full forward and the other puts full back, computer says thats neutral. If you did that, you'd get a "DUAL INPUT" aural warning. You should never hear that.

You NEVER use both side sticks at the same time.
(The exception to this is if one pilot takes control from the other pilot AND presses the red takeover button AND verbally takes control. You would then get a "PRIORITY RIGHT/LEFT" aural alert. You would always use the takeover button because you just do not know what control input they are making).


Example, you have a fairly inexperienced F/O landing the aircraft, who has passed his line check and is flying with an "ordinary" captain. The captain realises at 20ft the F/O hasn't started the flare. If the Capt pulled back on his sidestick without pressing the takeover button, and then the F/O pulled back on his sidestick a split second later too, both inputs are counted and added together (half backstick + half backstick = full backstick demand). Since you don't know what the other person is doing, you must take full control using the takeover button, or leave them in control. You can't just "help" them on the controls because that will often be worse than not intervening at all.



The only controls that are linked together are the rudder pedals. If one pilot's rudder pedals moves, so does the other.

[AerocatS2A]

There is a previous thread here, with precise info:
http://www.pprune.org/tech-log/559226-a320-dual-input-side-stick-priority.html#post8929993

Dual inputs are indeed averaged when both sticks are active. (As a software engineer with 40yrs experience I can say this is a thoroughly stupid idea.)

The software cannot therefore be termed an Expert System as it does not mimic the manual controls of old.

No wonder there're so many mishaps when Airbuses are flown by less experienced pilots, or non-English/French speakers.

Actually summing the inputs gives a reasonable approximation of manual controls. Imagine two pilots with the same strength, one pulling and the other pushing on the column, ignoring the pitch disconnect features for a moment, the result would be that the column doesn't move.

[VC10man]

When an Airbus co-pilot, who would use his/her right hand to control the plane, gets promoted to captain, is it difficult to get used to using their left hand to fly the plane? I've often wondered.

[Doug E Style]

Mr/Mrs Stains, you clearly know better than Airbus's engineers about all this. Why not give them a call and tell them where they're going wrong? I'm sure they'd love to hear your views.

[AerocatS2A]

When an Airbus co-pilot, who would use his/her right hand to control the plane, gets promoted to captain, is it difficult to get used to using their left hand to fly the plane? I've often wondered.
That's no different from any other pilot moving from right to left. FO flies conventional controlled aircraft with right hand on yoke and left on thrust levers while captain has their left hand on the yoke and right on the thrust levers.

[Phoenix1969]

All this talk of what happens when two pilots make different inputs on the sidesticks (and whether either is aware of what the other is doing) reminds me of AF447 :uhoh:

[+TSRA]

All this talk of what happens when two pilots make different inputs on the sidesticks (and whether either is aware of what the other is doing) reminds me of AF447 http://cdn.pprune.org/images/smilies/worry.gif


+1


When an Airbus co-pilot, who would use his/her right hand to control the plane, gets promoted to captain, is it difficult to get used to using their left hand to fly the plane? I've often wondered.


As Aerocat said, no - no difference between column and stick. However, there is an adjustment period where the pilot (regardless of control style) has to "learn to fly" from the opposite seat. It's not too bad the second or third time as you know what you're in for, but it can throw some guys for a bit of a loop. Eventually though, you get used to it and for us training guys flying from both seats becomes par for the course.