Altimeter setting gives negative altitude

Question

X-Plane 11.30. Situation: Aircraft: Alabeo M20R Ovation parked on the GA apron of Mosjoen airport (Kjaerstad), Norway (ENMS). According to Navigraph (Jepessen) charts the ENMS airport elevation is 240 FT. The METAR (https://en.allmetsat.com/metar-taf/western-southern-scandinavia.php?icao=ENMS) gives in this moment a barometric pressure of 999 hPa. This is equal to 29.5 inches mercury (I used the conversion function on: https://www.convertunits.com/from/inch+of+mercury/to/hPa). If I set the altimeter to 29.5 inches, using the Kollman's knob, the altimeter is showing an altitude of minus 240 FT. 

If I work the other way around: with the Kollman's knob set the altimeter to indicate an altitude of 240 FT (airport elevation), the altimeter setting shows a barometric pressure of 30.02 inches mercury which is equal to 1016,6 hPa. 

I guess setting the altimeter to the airport elevation would be the most realistic.

What do you advise me to do. 

Answer 1

Paulsk,

I believe the QNH you got from your website (999hPa) was no the same X-Plane was working with at that time (1016hPa). Try listening to ATIS (the X-Plane one, not the real one), if one is available for the airfield you are on, it will give you the current pressure X-Plane knows about. Setting it in the Kollman's windows will definitely give you the airfiled's elevation.

Alternatively, set your weather settings to matching real world conditions. And remember there still might be a difference between the real-world data and the sim's one.

Hope that helps.