I'm confused about how GPS units get updated databases. A panel might
have a GPS unit feeding into a multifunction display MX-20 or
Avidyne or something. Does one need to update both the
GPS and the MFD's databases to stay current? Doesn't this get
expensive and annoying?

Also, must one input the flight plan into both the MFD and
the GPS? It would seem both would need the information.


You enter your flight plan only once - on the GPS - and that information is
copied to the multi function display. The MFD has its own database for
terrain, towers, airports, navaids, airspace and stuff like that but the
flight plan waypoints come from the GPS. I know many people who keep only
the GPS with a current IFR database and then do a once a year update on the
MFD.

It would be really great if there was one place in the airplane where you
could plug in your laptop and update all the databases in the airplane in
one load, but that's not they way it works yet.