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Changing Vapp not possible, if approach was changed


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Hi,

 

My Setup: A320 Professional - P3D v5.1 latest HF. AviaServer for operating the MCDU on a Android tablet.

 

On the PERF page of the MCDU for the approach you can set beside other values the Vapp speed. Normally the proposed value fits quite well but there are cases, where you want to adjust it (gusty wind, etc.). This works fine, as long as you have not activate the approach of course. Then a change of values is not possible anymore, as far as I know.

 

At my last flight I was in cruise and had already entered all the values for approach (QNH, temperature, etc.). Then I got the information from the ATIS from the VATSIM controller, that the arrival runway has changed. I was still in cruise and changed the arrival procedure in the MCDU. Then I wanted to adopt the Vapp on the PERF page too, as the wind conditions have changed. But after the reprogramming of the arrival route I could no longer change the Vapp speed. It was not possible to enter a new value. Is this by design or is this a bug. I did not yet try to reproduce it yet, but will check this, if I have to change the arrival during flight the next time. Maybe this is a known "feature". Any input from A3xx experts is appreciated.

 

Rgds
Reinhard

 

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On 1/14/2021 at 12:58 PM, aua668 said:

Hi,

 

My Setup: A320 Professional - P3D v5.1 latest HF. AviaServer for operating the MCDU on a Android tablet.

 

On the PERF page of the MCDU for the approach you can set beside other values the Vapp speed. Normally the proposed value fits quite well but there are cases, where you want to adjust it (gusty wind, etc.). This works fine, as long as you have not activate the approach of course. Then a change of values is not possible anymore, as far as I know.

 

At my last flight I was in cruise and had already entered all the values for approach (QNH, temperature, etc.). Then I got the information from the ATIS from the VATSIM controller, that the arrival runway has changed. I was still in cruise and changed the arrival procedure in the MCDU. Then I wanted to adopt the Vapp on the PERF page too, as the wind conditions have changed. But after the reprogramming of the arrival route I could no longer change the Vapp speed. It was not possible to enter a new value. Is this by design or is this a bug. I did not yet try to reproduce it yet, but will check this, if I have to change the arrival during flight the next time. Maybe this is a known "feature". Any input from A3xx experts is appreciated.

 

Rgds
Reinhard

 

 

Quick answer: Yes, you can change it in CRZ. Maybe you tried to add too much and it was more than Vls+15??

 

So the way it works IRL is yes you can manually adjust the VAPP up to Vls+15kts (as far as I've played with it, this works on the AS Airbuses). The company I'm referencing only has pilots do this for suspected windshear.

The Airbus uses what's called GS mini, which is a feature that, when you're doing your approach in managed speed mode (speed knob pushed in), the aircraft will automatically compensate for winds and gusts during approach. This is not obvious to the pilots, but your target speed bug will move slightly up and down automatically. When you enter ATIS / TWR winds into the MCDU approach page, the airplane starts calculating speeds, and uses that reported wind to "detect" (really estimate / guess) a gust. No need to change your VAPP unless at our discretion we'd like to add a few knots for whatever reason. 

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Hi,

 

Many thanks for your answer. In the meanwhile I tried it out of curiosity on another flight. I changed the arrival procedure during CRZ and I could change Vapp as expected. So I could not reproduce the behavior. When it happened the last time there was no chance to enter any value there - the button was simply not reacting. So I assume, that under certain conditions there is a small bug, which blocks the input. And as you said, it is really seldom, that you correct the value. For the gust estimation - I am not sure, if Aerosoft has implemented that feature you described :) That's why I wanted to compensate the predicted gusts at that flight.

 

Thanks for sharing your experience.

 

Rgds
Reinhard

 

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On 1/21/2021 at 8:11 PM, aua668 said:

I am not sure, if Aerosoft has implemented that feature you described


GSmini is modelled on both smaller busses and A330. :)

As for the original issue reported. I have not been able to recreate this myself but will keep an eye out for it.

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