RAIM?

I've just told them we needed to wait for better satelite geometry,
and gave them a request to hold somewhere. Seems to have been clear
enough. We've held 10 minutes or so both times. the UNS's we have
allow us to predict raim, so that let us know that it should be fine
shortly. It also warned us we could expect the problem beforehand.
Stan
That seems to have bOn Sun, 30 May 2004 08:33:36 -0400, Roy Smith
wrote:

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"?

"Stan Gosnell" me@work wrote in message
...

Depends. You do need to tell ATC about it, and they should know
exactly what you're talking about.

That's hillarious. The FAA is so far behind GPS it's embarrasing. For
example we have an ILS here that requires DME because the OM and the other
fixes on the LOC approach are DME fixes. When the ILS DME is out of service
for any reason they NOTAM the whole approach out of service. I've been
fighting for a couple years with who ever will listen but to no avail.

"Roy Smith" wrote in message
...
Stan Gosnell me@work wrote:
RAIM warnings usually go away within a few minutes - I seldom see
them last 5 minutes.

That's the piece of information I was looking for. Thanks!

And a RAIM warning on an IFR box triggers a light on the panel. When the
light goes out you got your RAIM back.

In article ,
"Newps" wrote:

we have an ILS here that requires DME because the OM and the other
fixes on the LOC approach are DME fixes. When the ILS DME is out of service
for any reason they NOTAM the whole approach out of service.

What's the approach?

"Roy Smith" wrote in message
...
In article ,
"Newps" wrote:

we have an ILS here that requires DME because the OM and the other
fixes on the LOC approach are DME fixes. When the ILS DME is out of
service
for any reason they NOTAM the whole approach out of service.

What's the approach?


BIL ILS 28R

Teacherjh wrote:


It says I should contact ATC as soon as practical, but
what do I tell them?


Tell them you've had a GPS RAIM alert. You should decide what you want to do,
and tell them what it is. "Request the NDB 23 approach" "Request hold at
ALBEE for four minutes, then another GPS approach" "Request two all beef
patties, special sauce...."

You know, holding would be a so much better experience if ATC would provide this
take-out service.

Approach: Beech 32M, number 18 for the approach, hold west of SORRY intersection,
right turns, 8000. Expect further clearance in 35 minutes.

Beech: No problem, Approach. Could you send up some more dogs with special
sauce? Request pick-up at the fix. Our GPS integrity light is on again.

Approach, Roger 32M. Let us know if you require any additional holding time for
lunch.


I say no user fees without take-out.

On Sun, 30 May 2004 08:33:36 -0400, 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 CNX80 doesn't do RAIM.


Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)

"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.

WAAS GPS units do not use RAIM. For missed approach procedures in the event
of loss of RAIM, this is from chapter 1 of AIM:

3. If a RAIM failure/status annunciation occurs prior to the final approach
waypoint (FAWP), the approach should not be completed since GPS may no
longer provide the required accuracy. The receiver performs a RAIM
prediction by 2 NM prior to the FAWP to ensure that RAIM is available at the
FAWP as a condition for entering the approach mode. The pilot should ensure
that the receiver has sequenced from "Armed" to "Approach" prior to the FAWP
(normally occurs 2 NM prior). Failure to sequence may be an indication of
the detection of a satellite anomaly, failure to arm the receiver (if
required), or other problems which preclude completing the approach.

4. 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 Minimum Descent Altitude (MDA), but should proceed to the missed
approach waypoint (MAWP) via the FAWP, perform a missed approach, and
contact ATC as soon as practical. Refer to the receiver operating manual for
specific indications and instructions associated with loss of RAIM prior to
the FAF.

5. If a RAIM failure occurs after the FAWP, the receiver is allowed to
continue operating without an annunciation for up to 5 minutes to allow
completion of the approach (see receiver operating manual). If the RAIM
flag/status annunciation appears after the FAWP, the missed approach should
be executed immediately.

"Newps" wrote in
:

And a RAIM warning on an IFR box triggers a light on the
panel. When the light goes out you got your RAIM back.

Well, that depends. On our Trimble boxes we get a flashing
message light, and you have to check the message page to see
what happened. Then when RAIM comes back, we get another
flashing message light. The message light is annoying, because
it comes on for lots of things, many of them unimportant, some
of more importance. The Trimble units are really poorly
designed, and I would prefer almost anything else, but I don't
get a choice in any of this.

--
Regards,

Stan