Larry Dighera wrote:

Just get the local center frequencies from a Low Level chart, and
start making mayday calls.


To put what Larry says another way:

If you were on a flight following, receiving VFR advisories, or at least
listening to a local ATC channel before going down, the frequency you
were using will probably be heard by SOMEBODY in the area. Near an
airport, the CTAF might even be useful to contact someome airborne.

At least that's my plan... G

I was taught to use FF or advisories whenever possible, and NOT to leave
the frequency and change to 121.5 to make an initial emergency call.
The ATC center might instruct you to change, but at least you've
immediately got their attention. Other a/c might even see you go down,
if they know to look. Even on a local flight, I'll usually at least
monitor local app/dep channels.