I went up for currency with my (former) CFII. We were flying back to
San Carlos (KSQL) and on the GPS 30 approach. We were cleared to depart
OSI at a heading of 140. Norcal informed that they are going to fly us
7 miles past AMEBY. They flew us about 3 miles east south east of AMEBY
when they had us do a left turn direct AMEBY. I was perfectly
established and 2 miles out from the FAF the Garmin 430 went into
approach mode. I had the needles perfectly centered about 1 mile from
CUZUP (FAF) when I was kicked out of approach mode. We stayed at that
altitude as we are very familiar with the approach and terrain and we
skimmed one very thin cloud for about 5 seconds and then went fully
visual. During that time my CFII did a RAIM check. I thought it passed
but maybe I'm wrong. On the ground, he was unsure why we were kicked
out of approach mode. He thought it might be because we were more than
25 (?) degrees off of the AMEBY-CUZUP course but then again it
definitely went into approach mode before that. We were kicked out
while theh needles were dead centered.

Any ideas?

Gerald

maybe
http://gps.faa.gov/Library/Data/SatNav/satnavAugust-2005-text.htm


"G. Sylvester" > wrote in message
...
|I went up for currency with my (former) CFII. We were
flying back to
| San Carlos (KSQL) and on the GPS 30 approach. We were
cleared to depart
| OSI at a heading of 140. Norcal informed that they are
going to fly us
| 7 miles past AMEBY. They flew us about 3 miles east south
east of AMEBY
| when they had us do a left turn direct AMEBY. I was
perfectly
| established and 2 miles out from the FAF the Garmin 430
went into
| approach mode. I had the needles perfectly centered about
1 mile from
| CUZUP (FAF) when I was kicked out of approach mode. We
stayed at that
| altitude as we are very familiar with the approach and
terrain and we
| skimmed one very thin cloud for about 5 seconds and then
went fully
| visual. During that time my CFII did a RAIM check. I
thought it passed
| but maybe I'm wrong. On the ground, he was unsure why we
were kicked
| out of approach mode. He thought it might be because we
were more than
| 25 (?) degrees off of the AMEBY-CUZUP course but then
again it
| definitely went into approach mode before that. We were
kicked out
| while theh needles were dead centered.
|
| Any ideas?
|
| Gerald

This happened to me about a year ago on that approach (I'm based at
SQL) and sounds like almost the same point. It all came back after
about 15 seconds, the RAIM flag went away. I don't recall whether I
was still in approach mode or not, but like you I broke out about the
time I was figuring out my next move.

I've wondered whether there's some kind of signal interference from
the Stanford/SLAC vicinity once in a while. (This is pure speculation,
I have no data to support that.) Something also messes up 119.0 (tower
freq) in that area all the time.

-Jon C.


"G. Sylvester" > wrote in message
...
>I went up for currency with my (former) CFII. We were flying back to
>San Carlos (KSQL) and on the GPS 30 approach. We were cleared to
>depart OSI at a heading of 140. Norcal informed that they are going
>to fly us 7 miles past AMEBY. They flew us about 3 miles east south
>east of AMEBY when they had us do a left turn direct AMEBY. I was
>perfectly established and 2 miles out from the FAF the Garmin 430
>went into approach mode. I had the needles perfectly centered about
>1 mile from CUZUP (FAF) when I was kicked out of approach mode. We
>stayed at that altitude as we are very familiar with the approach and
>terrain and we skimmed one very thin cloud for about 5 seconds and
>then went fully visual. During that time my CFII did a RAIM check.
>I thought it passed but maybe I'm wrong. On the ground, he was
>unsure why we were kicked out of approach mode. He thought it might
>be because we were more than 25 (?) degrees off of the AMEBY-CUZUP
>course but then again it definitely went into approach mode before
>that. We were kicked out while theh needles were dead centered.
>
> Any ideas?
>
> Gerald

Jon Carlson wrote:
> This happened to me about a year ago on that approach (I'm based at
> SQL) and sounds like almost the same point. It all came back after
> about 15 seconds, the RAIM flag went away. I don't recall whether I
> was still in approach mode or not, but like you I broke out about the
> time I was figuring out my next move.
>
> I've wondered whether there's some kind of signal interference from
> the Stanford/SLAC vicinity once in a while. (This is pure speculation,
> I have no data to support that.) Something also messes up 119.0 (tower
> freq) in that area all the time.
>
> -Jon C.

thanks for the feedback. I know a Controller at OAK Center. He might be
able to direct me to someone at Norcal. If not, maybe just a NASA
Report. Maybe there were others as well. thanks.

Gerald

In article >,
"Jon Carlson" > wrote:

> I've wondered whether there's some kind of signal interference from
> the Stanford/SLAC vicinity once in a while. (This is pure speculation,
> I have no data to support that.) Something also messes up 119.0 (tower
> freq) in that area all the time.

What is on the ground in that area?

john smith wrote:
> What is on the ground in that area?

not much at all. A cement plant. About 7 miles away is an AM radio tower.

Gerald

In article >,
"G. Sylvester" > wrote:

> john smith wrote:
> > What is on the ground in that area?

> not much at all. A cement plant. About 7 miles away is an AM radio tower.

And whatever microwave transmitters are leasing space. :-))