I noticed when using X-Plane 12, there is a difference in the displayed vehicle altitude on the map and the altitude shown in the elevation profile window.  This prompts PF3 to keep telling me to maintain the target altitude.

 

Edited July 1, 20232 yr by lejacques

Quote

Actual aircraft altitude differs from indicated despite correct baro settings

Actual altitude shown in Little Navmap might differ from indicated altitude even with a correct baro setting.

This is an effect of the outside air temperature (OAT) on actual altitude where low temperatures affect the aircraft altimeter. When temperature is less than ISA conditions an aircraft will be lower than the altimeter reading.

This effect is currently modeled in X-Plane 12 and MSFS.

Corrections have to be applied when the aerodrome temperature is 0°C or colder:

• DH/DA or MDH/MDA and step-down fixes inside the final approach fix (FAF).
• All low altitude approach procedure altitudes in mountainous regions (terrain of 3000 ft AMSL or higher)

See SKYbrary - Altimeter Temperature Error Correction for more information.

Alex

Thank you.  I forgot to mention that the ATC calls to maintain altitude occur at cruise altitude (~35k ft) at STD pressure.