RAIM?

Roy Smith writes:

I've been doing most of my GPS flying with a CNX-80, which doesn't seem
to suffer from loss of RAIM. Last night I was flying with a GX-60, and
got a RAIM warning when commencing an approach.

The GX-60 manual isn't real illuminating on what you're supposed to do
at this point. Presumably, "continue the approach as if nothing
happened" would not be smart (although, being VFR, that's exactly what
we did last night).

So, what do you do? Ask ATC to hold someplace in the hopes the RAIM
warning goes away as the satellites shuffle around? If so, how long
would you expect this would take? Does the controller know enough about
GPS to understand what I mean if I tell him "I've got a RAIM alert"?

There was a thread about this on the CPA web based forum. The gist of
it was that there were issues with the GX50/GX60, related to the GPS
engine. If memory serves, UPSAT came up with a fix. Of course, Garmin
now owns the UPSAT line and the GX line has been discontinued, so
who knows. Call Garmin.

Unfortunately, the terms of use of the CPA web forum prevent me from
quoting the entire thread here.

-jav

"Roy Smith" wrote in message
...
I've been doing most of my GPS flying with a CNX-80, which doesn't seem
to suffer from loss of RAIM. Last night I was flying with a GX-60, and
got a RAIM warning when commencing an approach.

The GX-60 manual isn't real illuminating on what you're supposed to do
at this point. Presumably, "continue the approach as if nothing
happened" would not be smart (although, being VFR, that's exactly what
we did last night).

So, what do you do? Ask ATC to hold someplace in the hopes the RAIM
warning goes away as the satellites shuffle around? If so, how long
would you expect this would take? Does the controller know enough about
GPS to understand what I mean if I tell him "I've got a RAIM alert"?

implement plan B or C which does not need GPS

Roy Smith wrote:
I've been doing most of my GPS flying with a CNX-80, which doesn't seem
to suffer from loss of RAIM. Last night I was flying with a GX-60, and
got a RAIM warning when commencing an approach.

My subjective observation (is that the GX50/60 has more difficulties with RAIM
than other GPS receivers. IIRC the manual tells you to expect one in every 20
approaches, or maybe it says 5 percent of the time, or something like that.
People that fly behind other receivers seem never to get RAIM warnings.

Dave
Remove SHIRT to reply directly.

Tracking those section and subsections makes my head ache, but 1-1-19 is
clearly labeled "Doppler Radar" in my 2004 FAR/AIM.

Bob,

The latest AIM is available online at http://www.faa.gov/ATpubs/AIM/.

John Bell

How old is the database on the GX60? There were reports of GX database bugs
causing RAIM errors 3-6 months ago. Supposedly later additions of the
database have resolved this error. Also, does the GX-60 have a RAIM status
page? I usually do a RAIM check an hour or so out on the GNS430.

jerry

"Roy Smith" wrote in message
...
I've been doing most of my GPS flying with a CNX-80, which doesn't seem
to suffer from loss of RAIM. Last night I was flying with a GX-60, and
got a RAIM warning when commencing an approach.

The GX-60 manual isn't real illuminating on what you're supposed to do
at this point. Presumably, "continue the approach as if nothing
happened" would not be smart (although, being VFR, that's exactly what
we did last night).

So, what do you do? Ask ATC to hold someplace in the hopes the RAIM
warning goes away as the satellites shuffle around? If so, how long
would you expect this would take? Does the controller know enough about
GPS to understand what I mean if I tell him "I've got a RAIM alert"?

C J Campbell wrote:

"Teacherjh" wrote in message
...

Last night I was flying with a GX-60, and
got a RAIM warning when commencing an approach.

The GX-60 manual isn't real illuminating on what you're supposed to do
at this point.


Switch to your backup navigation system, which you've been using all
along.
This is one of the reasons why GPS is not authorized as a sole navigation
means
(you need to have a backup)

All of this is wrong.

All of what is wrong?