Accuracy of GPS in Garmin 430/530

"Will" wrote:
It may just be personal preference, but I see a lot of value in user
interfaces that make the data quality a primary display attribute at all
times. That way I not only know I have a GPS signal, but I can quickly
assess the quality of the signal. I see value in making this more than just
a binary state ("good enough for the FAA" GPS signal quality / "not good
enough for the FAA" GPS signal quality). Possibly that data could be
colored or made to blink in situations where integrity is compromised
sufficiently.

I disagree. We already have information overload. A binary "go/no-go" is
exactly what you want. If I told you that the SNR from satellite 17 was
down 6dB, what would you do with that information?

RAIM factors in signal strength as well as satellite geometry. To get a
good fix, you need to be getting a good signal from 4 satellites positioned
appropriately in both azimuth and elevation. Figuring out if the signal
strength and geometry is "good enough" is not the kind of problem people
can do in their heads.