Is Dual Input feature necessary during T/O & LDG?
 

There are plenty of tailstrikes/hardlanding due to both pilots manipulating the controls. The take-over button isnt as instinctive as it seems, especially in the last 30ft. Ideally, it could be undesirable for two inputs to algerbarically adding at such late stage.

How about, when a trainee pilot is flying, the 'dual input' logic is inhibited below 50ft for 1min, IF the Capt moves his side stick? There is no "Dual input" call-out but just a visual indication on FO side. This can be changed if the Capt/Trainer is sitting on the right.

What could be the possible disadvantage of this system? The advantage I see is, the Capt has to correct for only the visual cues that he/she perceives rather than being concious about what the FO is doing. Workload is greatly reduced, no need to change grips. Only one pilot flies the plane this way.

With appropriate training, using the takeover PB is instinctive. You must have your thumb on the button at all times though (which is a natural place to rest it with practice).

Without starting a discussion about the disadvantages of the not interconnected sidesticks, but do you have a source for that statement, any statistics, etc.?

The Airbus recommended techniques for taking over during take off and landing is by pressing the take over push button and keeping it pressed - irrespective of how many tenth’s of a second away we are from the main wheels touching the runway. From my personal experience I have found that it has worked well enough. I suppose it’s prudent to ensure you are not too late to exercise the use of it. Airbus golden rule - Take action if things do not go as expected. I am sure using the Prompt-Assist-Takeover model or its equivalent at your airline should help mitigate these issues.

As far as discussing the disadvantages of your proposed “software update” - why should it be deactivated for a training flight and not regular line flights? Are these tail strikes happening only during training flights with first officers on the CM2 seat?

How often is this trained?

I have over 5000 hours on the left and I never had to take control or gave a dual input. Dual input is a big no no by Airbus. Yes I had a few very positive landings but nothing even close to the limits. Max recorded VRTA was 1.78g and this is with barely no flare and hitting the ground with 500 feet/min on heavy A321. My outfit wants a written report if above 1.8G. A real hard landing by Airbus where maintenance action is due on A321 is over 2.6g. If you give a dual input at very low height like 15/10 feet or try to take over the landing at that stage cause you think there is not enough flare there is a chance you will make thing worsts by compressing the main gears especially on A321.

Ah! Good point. I only get trained about this when I became LTC. And it does not feel natural at all for me yet to have my finger on the red button. I need to work on that.

Great question. Not as much as it should be. But like Pineteam pointed out - DUAL INPUT is a big NO on the Airbus. With practice and self briefing one can ensure they use the takeover pb during such situations. The thumb rule I follow is - if the pilot on the other seat does not respond to the controls as I would at the time of flare/any other manoeuvre - I take over, as mentioned in the above posts - letting it go down to 15 feet or lower (at the time of flare on A321) before initiating a takeover would do more bad than good to the aircraft trajectory.

During first type rating, during command training, during instructor training. Then every 6 months during sim recurrents with intervention training.
Operators that do not put emphasis on this are in for some unpleasant surprises.

The logic of the sidesticks does not need to be changed; all it takes is proper training, like for everything else.

The data available are only incident reports. Dual-input caused hard landing/tailstrike are prevalent mostly in cases where the Capt is PM and I could find only 30 such events. However, many reports are still pending in the preliminary stages. Most of the landings between 1.7G-1.85G is not a reportable occurance. So the data is scarce. I'm only quoting from logic and experience.



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Agreed. However, if Airbus is clear that there should be only one pilot flying, and dual input is a big no-no, then why is it even there as an option at that stage? What could go wrong if the Capt takes over without having to worry about pressing a button (that he/she is not used to), calling out 'I have controls' and a blaring "Dual Input" alarm. The Capt simply takes over, the moment an input is sensed on the Capts stick. Inadvertent input on the stick may be an issue but there could be a threshold set like 2deg.

Are there any other disadvantages? I can't think of any.

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Sonic, 'training' :ok:

A pedantic expansion is that 'training' should be an education to explain and provide understanding.

e.g. What is the Airbus design philosophy, what is the engineering mechanisation and design view of how (when) the system is to be used?
Follow the published guidance; if not understood then ask Airbus:


https://safetyfirst.airbus.com/app/t...ick-inputs.pdf

Related
https://safetyfirst.airbus.com/app/t...me.php?p=68652

https://safetyfirst.airbus.com/app/t...-controls2.pdf

Edit: part 1 has greater relevance
https://safetyfirst.airbus.com/app/t...t-controls.pdf

I have always wondered about this. Why do Airbus side-sticks arithmetically add if they are never supposed to be operated together ? I think the intention is so that a TRE can grab the situation and pick up a wing in the event of a bad gust near the ground, or a missed flare, or a bounce, that a trainee does not react appropriately to, to avert a prang. If they also press the red button, fine, but even if they don't, they can still save the situation. I suspect that the "Dual Input" warning was provided for the trainee to be aware that their instructor was correcting on the non linked side-sticks.

Some years ago I was taxiing out at JFK and my Captain suddenly slammed on the brakes because I had slightly strayed off the centreline in a turn. The whole 230 tonne aircraft dipped and shuddered and lurched to a stop which was far too dramatic. If he had simply used his tiller to steer back onto the line and said something appropriate, it would have been far smoother and less alarming for all concerned, including the passengers.

.....Indeed as I myself did to another Captain when he went wrong - I just steered him back to the centreline with my tiller and asked if he was OK. No dramatic emergency stop required, just a gentle tweak.

Obviously, you absolutely do NOT want both pilots applying simultaneous inputs to their side-sticks routinely during normal flying or taxiing, but the facility is surely there for very occasional emergency corrections.

The only reason the inputs are algebraically added is because there is no better solution; it is the one that makes more sense from a design point of view.

The “Dual input” is a big no-no. It’s a warning rather than a caution like: “you are not supposed to be doing this”.

In your example of a bad gust near the ground you push the TakeOver PB and you correct. the sentence “I have control” is simultaneous to pressing the red button.

Trainees of any experience level have to be taught by the instructor from Day 1 that on Airbus FBW there is no room for “a little help in flare”. So if needed the instructor/cpt/FO (incapacitation) will takeover and no hard feelings. It’s absolutely normal.

Trained for captains at my company, never for FOs. In fact, having your hand on the sidestick when not PF will result in a thorough debriefing after the flight, as I found out to my cost when joining from another operator where PM covering the controls at critical phases of flight was routine. Though don't get me started on the other pilot resting their size 12s on the rudder pedals when I'm flying...

Wow… so not even the Capt. as PM can cover the side stick?

It’s amazing how many ways operators find to fly the same aircraft!

”Push and hold” is a mantra that runs through my head at about 4-500 ft when training, and like many colleagues I have taxied off the runway or found myself high up on a rejected landing with the button steel held down!

At my mob we train Captains in basic intervention and it is obviously a key part of the LTC course.

In my airline who flys close to 2000 sectors a day on the A320 series it is SOP for both pilots to hold the side stick. If a side stick fault developed or a takeover due, poor technique or incapacitation then you an immediately ready to take over. It is routine for the captain to take over during a poorly executed landing, for a number of reasons. I have had to do this several times over the years, including a long flare on short rwy. We must touch down in the touchdown zone and in my airline it’s SOP that the captain flys the baulked landing. I have never experienced or heard of any detrimental effects of duel input, the warning is very useful as it A, reminds the take over pilot to press the red button and B, reminds the other pilot to let go of their stick! Of course the pilot taking over needs to also announce I have control. It’s not a big deal and like I said is routine.

​​​​​​​Ah, no, should have been clearer. Captain can cover the side stick if FO is handling pilot.

I am sorry, but this is a complete nonsense. You should be ready to take over ANY TIME as PM. Scratching your balls as PM, wouldn't do the trick. Same goes for the rudder pedals.

Just don’t let me feel your feet on the pedals. If I can feel you on the pedals then I lose my feel of the aircraft. If you can’t be PM without putting your clogs on the pedals then just the fly it yourself.