When I am sitting at a sea level airport and manually set weather in settings: "Temperature at nearest airport" to 68 degF, the outside air temperature gauge in the LR Baron, (and in my VSkyLabs LongEZ), correctly shows 20 degC.
If I am sitting at KSKX Taos Regional at 7094 feet with "Temperature at nearest airport" set to 68 degF, in the LR Baron, and in my airplane (VSkyLabs LongEz), the outside air temperature gauge will read +5 degC (41 degF). Likewise 32 degF will show -11 degC (12 degF).
It appears X-Plane (11.31r1) is using the set value as the "temperature at sea level" and degrading the outside air temperature per the temperature drop by altitude change.
The problem also exists when X-IvAp downloads current weather for the departure airport during pre-flight. X-plane11.31r1 will decrease the downloaded temperature based on the departure airport's elevation. e.g. This morning the METAR report was M01/M11 A2987. X-IvAp applies the downloaded temperature and pressure over a period of 5 minutes. After 5 minutes the outside air temperature was reading -12 degC and my elevation went up (altimeter was adjusted to field elevation when manual set pressure was 29.92)
Does this wrong outside air temperature affect modeled performance, or carb and pitot icing? (I might have been seeing unusually high vertical climb rate; perhaps the derated temperature decreased the density altitude.)
(ps I filed this as a defect today.)