Garmin GNC 420W Pilots Guide - Page 249

APPENDIX C TROUBLESHOOTING When does turn anticipation begin, and what bank angle is expected? The GNC 420 smooths adjacent leg transitions based upon a nominal 15º bank angle (with the ability to roll up to 25º) and provide three pilot cues for turn anticipation: 1) A waypoint alert ('NEXT DTK ###°') flashes in the lower right corner of the screen 10 seconds before the turn point (Figure C-6). When does the CDI scale change, and what does it change to? The GNC 420 begins a smooth CDI scale transition from the 5.0 nm (enroute/oceanic mode) to the 1.0 nm (terminal mode) scale 30 nm from the destination airport (Figure C-7). The CDI scale further transitions to 0.3 nm (approach mode) at 2 nm prior to the FAF during an active approach. To return the CDI to the 1 nm scale in a missed approach situation, activate the missed approach sequence by pressing the OBS Key, as described in Section 6.2, Flying the Missed Approach. The CDI scale is also 1.0 nm within 30 nm of the departure airport. Figure C-6 CDI at 1 nm Scale 2) A flashing turn advisory ('TURN TO ###°') appears in the lower right corner of the screen when the aircraft is to begin the turn. Set the HSI to the next DTK value and begin the turn. 3) The To/From indicator on the HSI (or CDI) flips momentarily to indicate that the aircraft has crossed the midpoint of the turn. For more information on waypoint alerts and turn advisories, see Sections 6.2 and 6.3. 0.3 nm 1 nm MAP Approach FAF 2 nm Terminal 1 nm 1 minute 30 nm 5 nm Enroute/Oceanic Figure C-7 CDI Scale Transition 190-00140-20 Rev. K GNC 420(A) Pilot's Guide and Reference C-5