Could someone clarify the functions of the CDI knob in the upper right corner of the IFD540/440? I have read the manual but haven't found it to be very illuminating. And neither the iPad nor the PC simulators seem to work properly.

Specifically, can I make the IFD540 act as an old-fashioned VOR receiver by tuning the VOR frequency into the nav frequency box and then rotate the CDI knob one click until VLOC is displayed above it? In that case, can I set the OBS on my nav indicator or HSI and then track a radial like I did in the olden days?

If I push the center of the CDI knob I should get an OBS indication above it. Turning the knob should change the tracking radial. That seems to work if I'm tracking to a GPS waypoint, but can it be used to track to a VOR station? How does the rotation of the CDI knob in OBS mode relate to the OBS on a mechanical nav indicator or HSI? How about an intelligent HSI, like an Aspen?

Maybe the real question is: Is there any use for VLOC mode outside of shooting a VOR, localizer, or ILS approach? What if the GPS system were to fail or be jammed; can I use VLOC to do traditional VOR navigation?

Any enlightenment would be appreciated. Or better yet, a pointer to a lucid explanation in the manual that I overlooked.

Thanks

Mike

Thanks for the info.

Just to be sure, if I tune a valid VOR frequency and use the CDI knob on the IFD to select VLOC mode, I can navigate to the VOR using my old CDI or HSI. Any flight plan programmed into the IFD on the flight plan page will be ignored for the purposes of CDI needle deflection. However the programmed flight plan legs will still be shown on the map page and the IFD will still know where it is, as long as a valid GPS signal is being received. The VOR radial being tracked will not be shown on the map page.

Correct?

Has anyone gotten either of the simulators to simulate this stuff? It seems like the sim doesn't know anything about VHF navigation. The station IDs are never displayed, the VLOC mode indicator never turns green, and the GPS -> VLOC mode transition never happens. Am I missing something?

Thanks

Mike

I played with this on a flight over the weekend. I have the Mid-Continent CDI (306-series).

The IFD-540 does display the green/white radial line, BUT you won't see it if you have the CDI set precisely on your course because it is hidden under the magenta flight plan line. If I rotate the OBS on my CDI, then the green/white line comes into view on the IFD screen. Just like in the image posted above.

David Bunin