What button do I push on the instrument panel to activate DME in VOR navigation?
Typically, there isn't a &quot;button&quot; as such, you tune the DME to the frequency of the ground station (or slave it to the NAV radio).

The knob on the right is used to tune a frequency (shown before MHZ) when in &quot;frq&quot; mode, which is usually a VOR/DME. The numbers before NM is your distance to/from the station in Nautical Miles.