##### Omni Bearing Selector (OBS) Omni Bearing Selector. When used with a [[VOR]] or [[VORTAC]], the instrument can be referred to as an omni bearing indicator (OBI). The courseline is selected by turning an "omni bearing selector" or "OBS" knob usually located in the lower left of the [[indicator]]. It then shows the number of degrees deviation between the aircraft's current position and the [[radial]] line emanating from the signal source at the given [[bearing]]. >Covered in: >Mentioned in: >References: >Required by: > >Related to: