Matthias Markus

Ground Temperatur in INIT A

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When starting the aeroplane there is shown a groundtemperature on MCDU Init Page 1, that is not the real one outside. So you have to set the real groundtemperatur by yourself. Is that as in real Airbusses or should that be changed?

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4 hours ago, ABFan said:

When starting the aeroplane there is shown a groundtemperature on MCDU Init Page 1, that is not the real one outside. So you have to set the real groundtemperatur by yourself. Is that as in real Airbusses or should that be changed?

 

Here is a definition of the Ground Temp entry:

 

Ground temperature is normally entered during preflight. In flight the ground temperature defaults to a blank display (3 dash lines).

 

But (and it's a HUGE "But"), neither FMGS type for the Airbus's are perfect, especially when it comes to temps and cruise levels.  Though in a strange way, I actually have some direct experience with just these sort of calculations.  Basically, the calculations for temps, economic speeds and cruise levels and Tropopause are not only extremely complex, but the FMGS calculations can also be wrong with certain "correct" inputs.  For this reason, Airbus has recommended NOT changing the internally calculated Ground Temp or Tropopause figures.  CAVEAT:  If you Google this, you'll find a slew of sites/PDF/training documents that say for GND Temp you should enter the Ground Temp as it will be at Takeoff.  But again, Airbus engineers said NOT to do this and that appears to be the latest information on this.  Put another way, the values that auto-populate exist to mitigate the inaccuracies in the calculations.

 

So, we recommend that you leave both the above entries alone. If you decide to change them (hey, it's your aircraft!) then please don't report any bugs seen during flights where this info was changed.

 

I hope this answers your question!

 

Best wishes.

 

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Yep, today I was told by one of our test pilots, that this value IRL should be left at default if you use weather uplink.

 

 

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This is unrelated to the 3rd/Settings MCDU, so I moved it to the "standard" MCDU thread.

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