Okay... so it is now well established that 800MHz operation is illegal
in aircraft, and while 1900MHz operation is not prohibited by laws, the
reality is that it doesn't work that well over 2000AGL, more or less.

Now the real question---as a backup phone for traveling, does it make
more sense to go with a "cheapie" PCS-only phone, or pay more for
Verizon and a tri-mode phone, assuming that all modes are either illegal
or impractical in the air?

I have learned much from this discussion and in researching earlier ones!