ANATOMY OF THE VOR INDICATOR N 30 33 TO 24 E 15 S CDI (course deviation indicator) PUSH AUGUST 2014 / FLIGHT TRAINING / 49 6 21 OBS FR 3 W To/From flag 12 OBS knob 21 24 W E Deviation dots 3 12 15 S OBS (omni-bearing selector) 6 * The course deviation indicator (CDI) indicates the current course. If the needle is centered on the index mark, you are on the course. If it swings to either side, you are off course. * Selecting a radial is done through the omnibearing selector (OBS). Spinning the knob selects a radial, another term for a magnetic bearing. Pilots can either select a desired radial, or work backwards by centering the CDI and then reading off the radial. * The To-From flag indicates which side of the station you are on. Anytime you are flying to a station, the To flag should be selected. Likewise, flying away from the station or finding a position should be indicating with the From flag. * These deviation dots indicate how many degrees the aircraft is off the selected course. Each dot represents two degrees, for a total swing of 20 degrees from full left to full right deflection.