So Cal GPS Notam - Major Outages (Potential)

They say the GPS may be unreliable. Maybe not a bad thing to have VOR onboard after all! It appears it's a window of 1:00 AM - 4:00 AM PST, then 9:00 AM - 4:00 PM. Not ideal, but at least there should be no testing after 4:00, and the sun sets around 8:00 PM, so maybe some afternoon flying is in store (if at all) that day?

Thanks for posting! I missed this NOTAM
 
Last edited:
Interesting...not sure the airlines will be happy with "unreliable" GPS. It's a big deal all around if GPS is "unreliable" throughout So Cal. Even if it's not unreliable, the airlines and professional pilots have to assume it's potentially unreliable, and that's a big deal...
 
VWGhiaBob said:
Interesting...not sure the airlines will be happy with "unreliable" GPS. It's a big deal all around if GPS is "unreliable" throughout So Cal. Even if it's not unreliable, the airlines and professional pilots have to assume it's potentially unreliable, and that's a big deal...
Click to expand...

Only if your parents are of a pinkish hue and lack thickness.
 
VWGhiaBob said:
Interesting...not sure the airlines will be happy with "unreliable" GPS. It's a big deal all around if GPS is "unreliable" throughout So Cal. Even if it's not unreliable, the airlines and professional pilots have to assume it's potentially unreliable, and that's a big deal...
Click to expand...
I’d bet that most airline and corporate FMSs have DME/DME/DME positioning, so the only thing they’d really lose is RNAV approach capability, and ILSs predominate there anyway.
 
Do they give a specific reason why it will be unreliable? There have been several M and X class solar flares recently and they can affect reliability.
 
This happens pretty frequently here in SoCal. It's something to do with the military. I've flown during these NOTAMs a lot, and never once noticed any anomalies. RNAV approaches are still allowed.
 
This is potentially one of those times that we should be giving thought to before it happens. I see so many threads and even conversations among my aviation acquaintances about ripping out those useless boxes like Marker Beacons, DME’s, old fashioned NAV’s and even ADF’s. I have been a proponent of not being so quick to toss them in the trash can. No, I’m not going to retrofit one of my planes with one of these boxes, but if they are in place, operational and I don’t need the panel space for upgrades, why yank them out?

I probably will never experience a surprise satellite outage, but if it happens, it would be great to have a fall back position.

When it comes to flying I try to be a belt AND suspenders kind of guy. I think in terms of “what if?”
 
@MBDiagMan

Removing ADF and DME I get. It also increases UL since they are generally getting less and less viable.
VOR is the suspenders when your GPS belt breaks.

Tim

Sent from my HD1907 using Tapatalk
 
The phrase "Stop Buzzer" to ATC is supposed to cease the test if a pilot has a safety of flight issue. We seem to have these every six months or so just off the North Florida/South Georgia coast. Never have had an actual GPS issue during one of them.
 
The Children of the Magenta line should be worried…lol…
 
Direct C51 said:
This happens pretty frequently here in SoCal. It's something to do with the military. I've flown during these NOTAMs a lot, and never once noticed any anomalies. RNAV approaches are still allowed.
Click to expand...

I think one of the reasons that the advisory says GPS "may" not be available instead of "will" not be available can be seen on the chart of concentric rings provided. For example, taken literally, it predicts problems at 50 AGL at a radius of 139 NM, but as soon as you get even one NM farther away it's not until you get up to 4000 AGL. In reality, the altitude at which problems would occur would increase gradually with distance from the center, but that would be difficult to depict.

It's also difficult to predict the actual altitudes at which problems will occur, so they probably err on the side of caution.

Hopefully, the RAIM feature on an IFR GPS will let you know if you have a problem.
 
It’s funny, seems like every time I fly thru one of these GPS unreliable regions, I never experience any issues whatsoever. Always prepared for it but never run into it. Typically in and around the Louisiana area when they are published.
 
I ran into no GPS one day over New Mexico during these tests. It was out for maybe 45 min and 100 miles.
 
Arob16 said:
It’s funny, seems like every time I fly thru one of these GPS unreliable regions, I never experience any issues whatsoever. Always prepared for it but never run into it. Typically in and around the Louisiana area when they are published.
Click to expand...

I have flown through Patuxent MD area many times and lost GPS where the Navy does a lot of testing.

Tim
 
BRING BACK THE INS!
 
Sometimes these outages are to support weapon testing. Many of our cruise missiles, short range tactical missiles, and guided bombs have to function in a GPS-denied environment. A missile program might have, say, a six hour window of range time, and when the shot will actually go off depends on weather, range equipment, telemetry, etc., being “go.” The weapon flight might only last a minute or two.

But, the result is a NOTAM for 6 hours, with an actual outage only lasting 90 seconds somewhere in the middle of the window. You might not even notice the outage.
 
tspear said:
Removing ADF and DME I get. It also increases UL since they are generally getting less and less viable.
VOR is the suspenders when your GPS belt breaks.

Tim

Sent from my HD1907 using Tapatalk
Click to expand...
The trouble is that universal VOR coverage will be provided only at 10,000 ft and above in the future backup network. Good luck if you're in IMC at 6,000 ft with icing at 9,000 and GPS goes out over a sparsely-populated area — those VOR suspenders won't hold up your pants.

Even as NDBs thin out, my ADF can still point to an AM transmission tower, and it works at lower altitudes because it's not line-of-sight like VOR and DME. I'll remove it some day, but for now, it's still a valuable backup.
 
David Megginson said:
The trouble is that universal VOR coverage will be provided only at 10,000 ft and above in the future backup network. Good luck if you're in IMC at 6,000 ft with icing at 9,000 and GPS goes out over a sparsely-populated area — those VOR suspenders won't hold up your pants.

Even as NDBs thin out, my ADF can still point to an AM transmission tower, and it works at lower altitudes because it's not line-of-sight like VOR and DME. I'll remove it some day, but for now, it's still a valuable backup.
Click to expand...

AM is going away. FCC is moving the spectrum over to digital, A large portion of FM has already made the migration.
Unless something changed, when I last flew with an ADF (about 2014) it would not hold on a digital station.

In the scenario you present, I always play with the VOR when in cruise flight. All over the east coast I typically fly 5-9K with an occasional 3K or 11K just for variaty, and the whole time flying out west in May (roughly Dallas to Santa Fe to Cedar City to Provo to Omaha) I was able to pickup and maintain VORs. Out west I was flying VFR and way below the min nav altitude to avoid needing O2. I was often 3-6K AGL with a peak altitude of 11.5
I never had any issues with VOR. I could always find one to pick up. Was it the one that was direct on my route, nope. But I did get one.
In terms of the AM radio stations, they are very useless unless you know where the station is. Your better bet, get vectors from ATC.

Tim
 
Direct C51 said:
This happens pretty frequently here in SoCal. It's something to do with the military. I've flown during these NOTAMs a lot, and never once noticed any anomalies. RNAV approaches are still allowed.
Click to expand...

Happened to a friend of mine followed the GPS to a empty area in the Desert where there was supposed to be an airport. Dialed up the VOR at the airport and then flew 5 miles east following the VOR to the where the airport actually was. There was a notam for unreliable GPS at the time.
 
tspear said:
AM is going away. FCC is moving the spectrum over to digital, A large portion of FM has already made the migration.
Unless something changed, when I last flew with an ADF (about 2014) it would not hold on a digital station.

In the scenario you present, I always play with the VOR when in cruise flight. All over the east coast I typically fly 5-9K with an occasional 3K or 11K just for variaty, and the whole time flying out west in May (roughly Dallas to Santa Fe to Cedar City to Provo to Omaha) I was able to pickup and maintain VORs. Out west I was flying VFR and way below the min nav altitude to avoid needing O2. I was often 3-6K AGL with a peak altitude of 11.5
I never had any issues with VOR. I could always find one to pick up. Was it the one that was direct on my route, nope. But I did get one.
In terms of the AM radio stations, they are very useless unless you know where the station is. Your better bet, get vectors from ATC.

Tim
Click to expand...
VORs are not so plentiful in Canada (even before they started decommissioning some of them). I'd guess the situation in Alaska is similar.

Right now, in 2021, there are still NDBs and analogue AM transmitters, so the ADF makes sense. In 10 years, if that's no longer the case, the. I'll remove it,.but there's no point being premature.
 
brcase said:
Happened to a friend of mine followed the GPS to a empty area in the Desert where there was supposed to be an airport. Dialed up the VOR at the airport and then flew 5 miles east following the VOR to the where the airport actually was. There was a notam for unreliable GPS at the time.
Click to expand...
It's only a few years ago that the Canada Flight Supplement stopped including the bearing and distance from the nearest navaid in every airport entry. I took advantage of that info a few times early on.

The old timers back then were probably saying that a real pilot shouldn't need to rely on a newfangled VOR or NDB just to find an airport.
 
Last edited:
You must log in or register to reply here.
Back
Top