102Basic Operation• When an ILS or VOR approach is first selected or executed, the frequency is automaticallychecked, if correct. If the frequency is correct, you will not receive a message regarding thefrequency. If the frequency is incorrect, you will receive a message and you must place the ILSfrequency in the active frequency field by pressing the Menu/Enter key when the frequency mes-sage is received.• When flying a localizer-based approach (other than backcourse) with automatic CDIswitching enabled:1. “GPS” guidance may be used while flying outbound and on the initial portion of the procedureturn.2. “LOC” guidance is used on the remainder of the approach from the time you turn inbound onthe procedure turn. You will receive a message stating “AUTOSWITCH FROM GPS TO NAV.”3. The localizer frequency must be active to use “LOC” guidance at the MAP. The GNS 480 willautomatically switch back to GPS data for the missed approach.• When flying a localizer-based approach with automatic CDI switching disabled:1. You may select “LOC” guidance at any point on the approach prior to reaching the FAF.2. The localizer frequency must be active to use “LOC” guidance.Course Transitions Greater Than 270°For procedures that have heading or course changes in excess of 270 degrees, roll steering will not be availableuntil you have passed the point where a turn less than 270 degree turn can be accomplished. At this point adashed magenta line will show the path to the next leg in the flight plan. You may engage your roll steeringautopilot at this point.For an example where this might occur, see the Casper, WY (KCPR) departure, ALCOS3, from runway 12.Procedures
