Garmin GNC 420W Pilots Guide - Page 250

APPENDIX C TROUBLESHOOTING Why does my CDI not respond like a VOR when OBS mode is active? Unlike a VOR, the CDI scale used on GPS equipment is based on the cross-track distance to the desired course, not an angular relationship to the destination (Figure C-8). Therefore, the CDI deflection on the GPS is constant regardless of the distance to the destination, and does not become less sensitive when further away from the destination. For more information on the CDI scale, see Section 9.4. 22 nm nm 5 nm 5 nm GPS 5 nm 5 nm VOR Figure C-8 CDI Comparison What is the correct missed approach procedure? How do I select the missed approach holding point? To comply with TSO specifications, the GNC 420 does not automatically sequence past the MAP. The active-to waypoint sequences to the first waypoint in the missed approach procedure when the OBS Key is pressed after crossing the MAP. All published missed approach procedures must be followed, as indicated on the approach plate. To execute the missed approach procedure prior to the MAP (not recommended), select the Active Flight Plan Page, highlight the MAHP, press the Direct-to Key, and then press the ENT Key twice. How do I re-select the same approach or activate a new approach after a missed approach? After flying all missed approach procedures, the pilot may reactivate the same approach for another attempt from the Procedures Page. Once given clearance for another attempt, activate the approach from the Procedures Page by highlighting 'Activate Approach?' and pressing the ENT Key. The GNC 420 provides navigation along the desired course to the waypoint and rejoins the approach in sequence from that point on. See Section 5.2, Active Flight Plan Options for information on activating a specific flight plan leg. Activating a new approach for the same airport: 1) Press the PROC Key. 2) Turn the large right knob to highlight 'Select Approach?'. 3) Press the ENT Key. 4) Turn the large right knob to highlight the new desired approach. 5) Press the ENT Key to select the approach, then select the desired transition. 6) Highlight 'Activate?' at the bottom right corner of the screen and press the ENT Key to activate the new approach. Activating a new approach to a different airport: 1) Press the Direct-to Key. 2) Select the desired airport using the small and large right knobs. 3) Press the ENT Key to accept the selected airport, then follow the steps in the preceding paragraph to select an approach for the new airport. See Section 6.1 for more information on selecting and activating approaches. C-6 GNC 420(A) Pilot's Guide and Reference 190-00140-20 Rev. K