The yellow needle is the course select pointer (OBS), the moving part in the middle is the course deviation indicator (CDI) which displays the deviation (+/- 12 degrees) from the selected radial or course to or from the selected waypoint.
The yellow needle is the course select pointer (OBS), the moving part in the middle is the course deviation indicator (CDI) which displays the deviation (+/- 12 degrees) from the selected radial or course to or from the selected waypoint.