Jonathan Goodish wrote in message ...
In article ,
(Ron Lee) wrote:

Jonathan Goodish wrote:

In my opinion, there is no practical difference for enroute navigation
between a panel-mount certified GPS and a hand held which is not
certified.

Yes there is. RAIM provided integrity. As long as no signal error
exists (vast majority of the time) then your assertion is basically
correct.


But what if signal error exists? How is risk increased because of it
for enroute navigation? For practical purposes, it isn't.

My understanding is that RAIM calculates your location using all available
GPS signals and then goes back and "evaluates" each individual signal
against the collective result to determine the amount of error that exists.
If excessive error is present then that signal is disqualified from the
position calculation. Its only when not enough signals are left after the
disqualification process that the pilot will see a RAIM alert.