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  #1  
Old 05-06-2019, 04:48 PM
Geeman Geeman is offline
 
Join Date: Apr 2010
Location: Houston TX KDWH
Posts: 387
Default 430W loss of signal yesterday

I was flying in and around Mount Shasta (Northern California) north of Redding and received message on the 430W that I lost GPS signal. I was at 11,500 on north side of a 14,000 mountain. It came back about 5-10 minutes later as I was southbound.

I was enroute from Redding area for Lake Tahoe and doing a practice VFR GPS 18 approach into South Lake Tahoe. Between the IAF and the FAF about 8500 ft I lost the signal again. It came back just before the missed approach point.

During this time I had foreflight on an IPAD and never lost position on the map. I also had a 696 and it showed me on the moving map but I lost the approach course on the 696 that the 430 sends to it.

Question 1: Do you think this was an antennae issue or a GPS loss of signal in the area? Did it not have enough antennas in sight for the 430, but enough to run the ipad/696?

Question 2: I was in VMC. What the heck would you do in IMC during a "real approach". Lets say I did not have the IPAD or 696. The missed approach is a GPS waypoint, how would you navigate to it. What if you could not get ATC for a vector due to mountains. I realize I was over the lake and could have done a 180 and climbed over the lake...but that is not the published route. I also realize this would be an emergency and do what I needed to do to, but what is the recommended course of action?

Never had this happen before. Flown behind a few 430's.
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RV-7 Kit (sold to purchase C150 to train my kids)
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Last edited by Geeman : 05-06-2019 at 05:02 PM. Reason: added more info
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  #2  
Old 05-06-2019, 05:04 PM
sglynn's Avatar
sglynn sglynn is offline
 
Join Date: Mar 2008
Location: Anacortes, WA
Posts: 832
Default loss of gps

Well there was a time before GPS. And basically when we are following the magenta line, we are on a heading. The maps and charts whether paper or on iPad do show headings. So overall navigation is doable for awhile. Under VFR I'm not sure its an emergency. Asking center for a vector is ok. Even the approach is all about headings. But if your GPS is driving your OMNI needles during an approach and they went south you'd have to go missed and perhaps find an ILS or VOR approach. If you are IFR relying on /G that's probably an emergency.
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  #3  
Old 05-06-2019, 05:58 PM
Flandy10 Flandy10 is offline
 
Join Date: Dec 2007
Location: Peachtree City, GA
Posts: 145
Default

Quote:
Originally Posted by Geeman View Post
I was flying in and around Mount Shasta (Northern California) north of Redding and received message on the 430W that I lost GPS signal. I was at 11,500 on north side of a 14,000 mountain. It came back about 5-10 minutes later as I was southbound.

I was enroute from Redding area for Lake Tahoe and doing a practice VFR GPS 18 approach into South Lake Tahoe. Between the IAF and the FAF about 8500 ft I lost the signal again. It came back just before the missed approach point.

During this time I had foreflight on an IPAD and never lost position on the map. I also had a 696 and it showed me on the moving map but I lost the approach course on the 696 that the 430 sends to it.

Question 1: Do you think this was an antennae issue or a GPS loss of signal in the area? Did it not have enough antennas in sight for the 430, but enough to run the ipad/696?

Question 2: I was in VMC. What the heck would you do in IMC during a "real approach". Lets say I did not have the IPAD or 696. The missed approach is a GPS waypoint, how would you navigate to it. What if you could not get ATC for a vector due to mountains. I realize I was over the lake and could have done a 180 and climbed over the lake...but that is not the published route. I also realize this would be an emergency and do what I needed to do to, but what is the recommended course of action?

Never had this happen before. Flown behind a few 430's.



This sounds a lot like a GPS interference testing issue. Did you check the notams? I was southbound through Florida and my 650 lost all position data. My G3X never lost the position lock, but the 650 was out to lunch. Jax center did not have any information when I asked, so I thought I had a problem. Needless to say, I spent days checking wiring and was almost ready to ship the 650 back to Garmin with its associated cost, when I went back and found the website. And yes, it was listed for the day I flew.

The testing WILL take out any WAAS receiver but wont hurt a Non-WAAS.
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  #4  
Old 05-06-2019, 06:23 PM
sailvi767 sailvi767 is offline
 
Join Date: Sep 2010
Location: Charlotte NC
Posts: 1,309
Default

Sounds like the Navy jamming GPS in the NAS Fallon training ranges.
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  #5  
Old 05-06-2019, 06:30 PM
BobTurner BobTurner is offline
 
Join Date: Dec 2011
Location: Livermore, CA
Posts: 7,433
Default

Q2: This is where position awareness is everything. I was up there just a few weeks ago, and ATC radar does not reach down into the lake basin. If you're aware of where you are, then it's obvious (?) that you need a climbing right turn to stay out over the lake while you climb. If you start low, you'll need to turn the turn into a circle. If the wind is the usual out of the west, you'll want to slightly favor going more west than east on each turn, to stay over the lake. When you get high enough ATC will see you and can vector you somewhere.

And yes, gps outages/interference happen. About a few months ago, going into LVK (VFR, "student" under the hood) the 650 first downgraded from LPV to LNAV; then, a big red X and no gps.
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  #6  
Old 05-06-2019, 06:50 PM
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AlexPeterson AlexPeterson is offline
 
Join Date: Sep 2005
Location: Ottertail, MN
Posts: 2,423
Default

Since your ipad and 696 didn't lose signal, it wasn't jamming. Several years ago I had intermittent loss of signal on my 430w. I don't fly IFR so I decided to wait until it conked out for good. Anyway, it never did but it was a faulty antenna. I used to get the error every couple months or so, and it would come back after several minutes. It's been a number of years since replacing the antenna and the problem has never recurred.
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  #7  
Old 05-06-2019, 08:06 PM
rv7charlie rv7charlie is offline
 
Join Date: May 2006
Location: Pocahontas MS
Posts: 3,888
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I have no advice at all about IFR, but when I discovered that the EFIS I'm using will allow a 'backup' gps, I bought one of the cheap pucks that can see all the different countries' constellations. The one I've got lets you pick two constellations, so...if the gubmnt is monkeying with gps, GLONASS or another constellation might be still available.

For VFR me, it's more of a convenience thing, but I wonder if it might be a plan C or D, even in an IFR environment.
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  #8  
Old 05-06-2019, 08:42 PM
jpowell13 jpowell13 is offline
 
Join Date: Nov 2008
Location: Baton Rouge, LA
Posts: 686
Default Loss of GPS signal

I was loosing GPS reception to my 400W. It was caused by my iLevil ADSB/GPS receiver being located too near my glare shield mounted Garmin antenna. The problem was easily identified by turning the Garmin to the reception strength screen and moving the iLevil (also turned on) toward the Garmin antenna. The bars dropped down rapidly as the iLevil got closer to the Garmin antenna. John
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  #9  
Old 05-06-2019, 08:52 PM
Geeman Geeman is offline
 
Join Date: Apr 2010
Location: Houston TX KDWH
Posts: 387
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Quote:
Originally Posted by jpowell13 View Post
I was loosing GPS reception to my 400W. It was caused by my iLevil ADSB/GPS receiver being located too near my glare shield mounted Garmin antenna. The problem was easily identified by turning the Garmin to the reception strength screen and moving the iLevil (also turned on) toward the Garmin antenna. The bars dropped down rapidly as the iLevil got closer to the Garmin antenna. John
Maybe on to something. I just put a spot gps tracker in the plane the day before. It?s about 30? away from the GPS antenna. Maybe I should move it.
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Purchased and sold flying RV-6
RV-7 Kit (sold to purchase C150 to train my kids)
Purchased flying RV-7
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  #10  
Old 05-06-2019, 09:03 PM
lr172 lr172 is offline
 
Join Date: Oct 2013
Location: Schaumburg, IL
Posts: 6,106
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Quote:
Originally Posted by sailvi767 View Post
Sounds like the Navy jamming GPS in the NAS Fallon training ranges.
And the ipad and 696 have some special technology to receive GPS signals during Navy jamming?
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