Is it legal to use a VFR only GPS for DME on an IFR flightplan in IMC? I assume not but I'm not sure if there's some stipulation for using it for DME when not using it to follow a course...
Negative.Is it legal to use a VFR only GPS for DME on an IFR flightplan in IMC?
Negative. If the database is out of date, all you have to do is verify the accuracy of all the waypoints that you will use on the flight. If they check, you're good to go.To use a GPS for ADF or DME the unit must be IFR-certified and it must have a current database loaded into it.
You can use the VFR GPS as the backup, not the other way around.It specifically states in the AIM about using GPS in lieu of DME/ADF that only an IFR certified gps can be used. You can use a VFR gps for en route nav (we do it 99% of the time) just as long as you have suitable backup navigation.