RAIM?

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"?

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)

Jose

--
(for Email, make the obvious changes in my address)

You have no in-panel backup for a GPS approach not based on a VOR or some
other navaid. And that's authorized. If the RAIM warning persists you'd have
to treat it as navigation-equipment failure and discontinue the approach and
of course tell ATC. If the missed approach fix is also a GPS-only waypoint,
you'll need vectors to it. If you're not in radar coverage you've got
another problem; you have to know what a safe course of action is
considering the terrain.

"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)

Jose

--
(for Email, make the obvious changes in my address)

"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.

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?

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.

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"?

He's probably ask you why you were worried that it was raining? :-)

Seriously, good question, and I haven't seen this addressed yet in
anything I've read. Must be in the fine print somewhere though.


Matt

Look to the AIM, not the manual. 1-1-20(j)(3) makes it clear.

Bob Gardner

"Matt Whiting" wrote in message
...
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.

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"?

He's probably ask you why you were worried that it was raining? :-)

Seriously, good question, and I haven't seen this addressed yet in
anything I've read. Must be in the fine print somewhere though.


Matt

In article ,
"Bob Gardner" wrote:

Look to the AIM, not the manual. 1-1-20(j)(3) makes it clear.

Thanks for the reference (although, it looks like it's really 1-1-19,
not 1-1-20, at least in the version I've got). While that does clear
things up a bit, it still leaves one with a bit of head-scratching to do.

The immediate action is clear; continue to fly the approach track, but
do not descend to the MDA, and execute the missed when you reach the
MAWP.

But what then? It says I should contact ATC as soon as practical, but
what do I tell them? Presumably, I start with the obvious, "New York,
3875T, missed approach", but what do I want to do after that? If I just
get vectors back for another shot, is it likely that the condition which
caused the RAIM alert will have resolved itself by then?

Is there a standard phrasology for telling the controller you had a RAIM
alert? It seems like there should be some compact way to say, "I had a
problem with my GPS equipment, but don't worry, it'll fix itself in a
little while".

Tracking those section and subsections makes my head ache, but 1-1-19 is
clearly labeled "Doppler Radar" in my 2004 FAR/AIM. In any event, a section
titled "Receiver Autonomous Integrity Monitoring," in subsection (3), tells
the reader that if a RAIM/status annunciation occurs prior to the final
approach waypoint, the approach should not be completed since GPS may no
longer provide the required accuracy." Subsection (4) says: "If the receiver
does not sequence into the approach mode or a RAIM failure/status
annunciation occurs prior to the FAWP the pilot should not descend to MDA
but should proceed to the missed approach waypoint (MAWP) via the FAWP,
perform a missed approach, and contact ATC as soon as practicable."

With the exception of telling us how to pronounce fiver and niner and how to
report altitudes, the AIM is not big on pilot phraseology, as you know. ATCH
tells controllers exactly what to say, with little wiggle room, but pilots
have no similar publication to refer to...and I suspect that that situation
will not change.

Bob Gardner
"Roy Smith" wrote in message
...
In article ,
"Bob Gardner" wrote:

Look to the AIM, not the manual. 1-1-20(j)(3) makes it clear.

Thanks for the reference (although, it looks like it's really 1-1-19,
not 1-1-20, at least in the version I've got). While that does clear
things up a bit, it still leaves one with a bit of head-scratching to do.

The immediate action is clear; continue to fly the approach track, but
do not descend to the MDA, and execute the missed when you reach the
MAWP.

But what then? It says I should contact ATC as soon as practical, but
what do I tell them? Presumably, I start with the obvious, "New York,
3875T, missed approach", but what do I want to do after that? If I just
get vectors back for another shot, is it likely that the condition which
caused the RAIM alert will have resolved itself by then?

Is there a standard phrasology for telling the controller you had a RAIM
alert? It seems like there should be some compact way to say, "I had a
problem with my GPS equipment, but don't worry, it'll fix itself in a
little while".

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