HEADQUARTERS OH-58A - Page 143

TM 55-1520-228-10
Change 11 3-23
CONTROL/INDICATOR FUNCTION
1. Course Pointer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Indicates deviation from selected VOR radial or LOC path.
2. Course Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Provides reference point for course deviation card.
3. Course Deviation Card . . . . . . . . . . . . . . . . . . . . . . . Manually rotated card, driven by OBS control to indicate de-
sired VOR radial directly beneath course index.
4. NAV Warning Flag . . . . . . . . . . . . . . . . . . . . . . . . . . . Red NAV flag indicates VOR or LOC signal is unreliably
weak or malfunction in receiver.
5. To/From Flag . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Indicates whether flying selected radial would direct helicop-
ter toward (TO) or from (FR) VOR station.
6. Omnibearing Selector (OBS) . . . . . . . . . . . . . . . . . . Drives course deviation card for course selection.
7. Reciprocal Course Index . . . . . . . . . . . . . . . . . . . . . Indicates radial 180 degrees from selected radial.
8. Glide Slope Warning Flag . . . . . . . . . . . . . . . . . . . . . Red GS flag indicates GS signal is unreliably weak or mal-
function in receiver.
9. Glide Slope Pointer . . . . . . . . . . . . . . . . . . . . . . . . . . Indicates deviation from glidepath.
10. Blue/Yellow Off Course Indicator . . . . . . . . . . . . . . . Indicates deviation from selected course.
206075-266
Figure 3-12. Course Deviation Indicator (CDI) C