I fly around with no external indication at all, so to find my way around I have to use NAV equipment; in case of older planes this is navigational marker on radiocompass. Oftentimes, instead of correct bearing it chooses to show me the butt for some reason. This is the case, for example, for F-106 pit and others based on it
After looking into the matter the culprit is found. Originally, it looks like this:
[CourseArrow]
Type=COURSE_ARROW
NodeName=HSIcenter
MovementType=ROTATION_Z
ValueUnit=DEG
Set[01].Position=00.0
Set[01].Value=0.0
Set[02].Position=360.0
Set[02].Value=360.0
[CourseCounter]
Type=COURSE_ARROW
CounterNodeFormat=course_dig%d
MovementType=ANALOG_COUNTER
ValueUnit=DEG
While it should be:
[CourseArrow]
Type=BEARING_MARKER
NodeName=HSIcenter
MovementType=ROTATION_Z
ValueUnit=DEG
Set[01].Position=00.0
Set[01].Value=0.0
Set[02].Position=360.0
Set[02].Value=360.0
[CourseCounter]
Type=BEARING_MARKER
CounterNodeFormat=course_dig%d
MovementType=ANALOG_COUNTER
ValueUnit=DEG
After looking into the pits made by Stary, the following is found too:
[CourseArrow]
Type=BEARING_MARKER
//Type=COURSE_ARROW
NodeName=course_arrow
MovementType=ROTATION_Y
ValueUnit=DEG
Set[01].Position=00.0
Set[01].Value=0.0
Set[02].Position=360.0
Set[02].Value=360.0
[BearingMarker]
Type=MAGNETIC_COMPASS
//Type=BEARING_MARKER
NodeName=bearing_marker
MovementType=ROTATION_Y
ValueUnit=DEG
Set[01].Position=00.0
Set[01].Value=0.0
Set[02].Position=360.0
Set[02].Value=360.0
So apparently, CourseArrow became BEARING_MARKER while BearingMarker is now just MAGNETIC_COMPASS. Not sure when it happened, between SF1 and SF2 (never played SF1 for that matter), or later during updates...
In case if you encounter the same problem and want it gone, find the node which is ought to show you the correct course and define it as BEARING_MARKER. Works for analog counters as well