Garmin GPS 155XL Pilot's Manual & Reference

Also see for GPS 155XL: Maintenance manual Installation manual Installation manual

126APPENDIXG TROUBLE-SHOOTINGQ & AWhat does the GPS APR switch do? What is ‘arming’ an approach?The GPS APR switch must be set to the ARM position for an approach to enter theactive phase. It may be left in the ARM position to simplify approach operation. Itsmain function is to provide the pilot with a quick method of deactivating the approachand returning the CDI scale to the 1 nm scale in the event of a missed approach. Formore on the GPS APR switch and arming approaches, see pages 74-75.What does the GPS SEQ switch do and when do I use it?The GPS SEQ switch is used to select manual or automatic waypoint sequencing ofwaypoints. Setting the GPS SEQ switch to the HOLD position holds your current‘active to’ waypoint as your navigation reference and prevents the GPS from sequenc-ing to the next waypoint. When the GPS SEQ switch is set to the AUTO position,automatic waypoint sequencing is selected, and the GPS will automatically select thenext waypoint in the route once the aircraft has crossed the present active-to waypoint.AUTO HOLDAutomatic sequencing of waypoints Manual sequencing- ‘HOLDs’ on selected waypointChange in HSI does not affect CDI deflection Manually select course to next waypoint from HSIAlways navigates ‘TO’ the active waypoint Will indicate ‘TO’ or ‘FROM’ waypointMust be set to AUTO for approach to go active Approach will not go activeThe GPS SEQ switch must be set to the HOLD position any time you are deviatingfrom the flight sequence of an approach (e.g., when you are flying radar vectors) orwhen you must cross the same waypoint twice in succession (e.g., a procedure turn orholding pattern). Whenever the GPS SEQ switch is set to the HOLD position, the GPS155XL allows you to select the desired course to/from a waypoint using the HSI, muchlike a VOR, and display a to/from flag for the active-to waypoint. In the AUTO posi-tion, the CDI will always display a ‘TO’ indication for the next waypoint once you’vecrossed the active waypoint. Refer to page 88 for an approach example using a HOLD.