QFE and QNH Altimeter
QFE and QNH Altimeter Settings
Generally it can be said that:

When setting the QFE (FE = Field Elevation) value the altimeter will show 0 feet because it simply shows height above the airfield.

When setting the QNH (NH = Nautical Height) value, the altimeter will show the altitude above mean sea level. So in UUWW, runway 01 it will show approx. 630 feet.
Procedures:

In Russian Airspace at or above transition altitude / height / level the same Flight Levels (FL) in [ft] system is used.

Below transition altitude / height / level the procedure depends on whether or not you can actually set the QFE value in the FCU.

Aircraft that do not have a QFE setting avaible for the altimeters, a conversion of the reported QFE value into the corresponding QNH value has to be made.

In the example we will use the airport UUWW/Vnukovo. The threshold for runway 01 is 630 [ft] above Sea Level.
Example
Lets assume the reported QFE is 997. On Lido charts you might find a published QFE/QNH conversion value. On Jeppesen (Navigraph) you do not. You will need to calculate the QNH value yourself. What you come up with? (Click to open)
Knowing that 1 hPa equals 27 [ft] difference, we take the threshold elevation and divide it by 27.
So: 630 divided by 27 equals a pressure difference (between QNH and QFE) of 23 hPa.
Now we can derive the QNH by adding 23 hPa from the QFE: 997 + 23 = 1020 hPa QNH.
When you set this value in the Altimeters, they will show a value of 630 feet, i.e. The height above MSL.
Please download the PDF for the full walkthrough (sadly outdated in current Navdata).
Warning
ONLY for FlightSimulation!