GPS signal may be unreliable or unavailable within a 313NM radius

[JasonM]

Guess we can trust the GPS the 27th to the 31st? Is this saying that if I stay below 10K feet, that the radius will only effect an area 197 miles from Wilmington NC?

https://www.faasafety.gov/files/notices/2013/Oct/CSFTL_13-08_GPS_Flight_Advisory.pdf

FEDERAL AVIATION ADMINISTRATION


FLIGHT ADVISORY
GPS Testing
CSFTL GPS 13-08
27 - 31 Oct, 2013
Wilmington, NC
GPS testing is scheduled as follows and may result in unreliable or unavailable GPS signal.

Location: Centered at 341000N/0765500W or the Wilmington VOR /ILM/ 103 Radial at 49NM.
A. Dates and times:

27 Oct 13 1100Z – 1630Z
28 Oct 13 1830Z – 2359Z
29 Oct 13 0000Z – 0030Z 1700Z – 2300Z
30 Oct 13 1100Z – 1700Z
31 Oct 13 1100Z – 1700Z

B. Duration: Each event may last the entire requested period.

C. During testing, the GPS signal may be unreliable or unavailable within a 313NM radius
centered at 341000N/0765500W or the Wilmington VOR /ILM/ 103 Radial at 49NM at
FL400 and above, decreasing in area with decrease in altitude to 263NMR at FL250,
197NMR at 10,000 FT MSL, 159NMR at 4,000 FT AGL and 119NMR at 50 FT AGL.

D. Pilots are strongly encouraged to report anomalies during testing to the appropriate
ARTCC to assist in the determination of the extent of GPS degradation during tests.


The NOTAMs discussed in this advisory may change with little or no notice. Pilots are
advised to check NOTAMs frequently for possible changes prior to operations in the
area. NOTAMs will be published at least 24 hours in advance of any GPS tests.

 

[eman1200]

just can't seem to find a good gps mechanic when you need one!

 

[JasonM]

just can't seem to find a good gps mechanic when you need one!

I'd say this is going to directly affect your long XC this weekend in NC. I'll be honest, while I always realized I needed to do everything without the GPS, I always felt good knowing it was right there if I needed it. Study that route good and watch out for any commercial airlines on GPS approaches.

 

[dans2992]

What are they doing that requires this? I see these notices quite often.

 

[Apache123]

According to the Notam fly 50'AGL for best gps coverage.

 

[Frank]

According to the Notam fly 50'AGL for best gps coverage.

That will also ensure your aircraft gets the best ground coverage, too.

 

[Frank]

OK- so how are the airlines going to do IFR flights after they decomission all the VORs, if they are also going to screw around with GPS over such wide areas?

 

[MAKG1]

OK- so how are the airlines going to do IFR flights after they decomission all the VORs, if they are also going to screw around with GPS over such wide areas?

Why does everyone think all the VORs are going to get decomissioned?

It ain't gonna happen. The FAA is quite aware that reliance upon a single method of navigation is a vulnerability.

 

[Old Geek]

What are they doing that requires this? I see these notices quite often.

I'd guess a military exercise. Jamming (or denial as they call it) of the public available signal while the military works under it.

 

[Norman]

Testing a new WAAS ground station?

 

[dans2992]

I'd guess a military exercise. Jamming (or denial as they call it) of the public available signal while the military works under it.

That's what I always assumed, but if they're really jamming, it's a rather large inconvenience to the public to do it as often as they do.

Has anyone ever actually experienced a GPS outage due to these kinds if activities?

 

[bullwinkle]

150-300 miles is a huge area. Something more than GPS maintenance going on.

 

[dans2992]

This happens on pretty much a monthly basis out here in the southwest.

 

[N801BH]

I get a kick out of the statement "unavailable within a 313NM radius"

I mean..... why not 312 miles or 314 miles ??

 

[eman1200]

I'd say this is going to directly affect your long XC this weekend in NC. I'll be honest, while I always realized I needed to do everything without the GPS, I always felt good knowing it was right there if I needed it. Study that route good and watch out for any commercial airlines on GPS approaches.

I try to fly higher than the gps stations, so I should be fine

that, and right now I'm scheduled for the 26th, hopefully before they start their work. but def worth noting, just in case.

 

[bbchien]

I get a kick out of the statement "unavailable within a 313NM radius"

I mean..... why not 312 miles or 314 miles ??

See the string about engineers.....

 

[JeffDG]

See the string about engineers.....

Or they told the FAA "360 miles" and they converted to nm.

 

[kyleb]

I get a kick out of the statement "unavailable within a 313NM radius"

I mean..... why not 312 miles or 314 miles ??

I'm guessing the original data said "500 KM" (which converts to just under 311 miles), and someone used a conversion factor that was slightly off.

 

[gismo]

That's what I always assumed, but if they're really jamming, it's a rather large inconvenience to the public to do it as often as they do.

Has anyone ever actually experienced a GPS outage due to these kinds if activities?

I can understand the need to test susceptibility to jamming but I don't see why this can't be done out in the ocean somewhere well away from regular traffic.

 

[SCCutler]

I just fire up my trusty LORAN unit and...


...oh, never mind!

 

[ElPaso Pilot]

That's what I always assumed, but if they're really jamming, it's a rather large inconvenience to the public to do it as often as they do.

Has anyone ever actually experienced a GPS outage due to these kinds if activities?

Yes, and wacky GPS readouts to boot. 50K' altitudes and mach groundspeeds in the Mooney on one trip over Oklahoma, as I remember. Someone apparently pushed the button to shift the GPS location by a whole bunch, and my poor Garmin was trying hard to get me there.

I pull that data log out once in awhile for the "I don't need to know how to use paper, ever, I've got a nifty box here" kiddies.

 

[N801BH]

I can understand the need to test susceptibility to jamming but I don't see why this can't be done out in the ocean somewhere well away from regular traffic.

Ya can't do that......

It make too much sense...

 

[MAKG1]

Ya can't do that......

It make too much sense...

Yup, testing effects of terrain, foliage, etc., makes sense in the open ocean .... no, wait.

And everyone knows there aren't any aircraft out there. And lots of VORs and LORAN stations ....

It's a whole lot cheaper to haul out your ground station and testing team into the middle of the ocean.

Might want to think this through a bit. Especially since pilots are supposed to be competent enough to navigate without a magic box.

 

[N801BH]

Yup, testing effects of terrain, foliage, etc., makes sense in the open ocean .... no, wait.

And everyone knows there aren't any aircraft out there. And lots of VORs and LORAN stations ....

It's a whole lot cheaper to haul out your ground station and testing team into the middle of the ocean.

Might want to think this through a bit. Especially since pilots are supposed to be competent enough to navigate without a magic box.

Personally I think the majority of these tests are nothing more then the guvs ability to impart doubt in the publics mind and to show their abilty to cause the GPS constallation to be disabled at their whim.. The guv seems to be able to give warnings but the reason for all the tests are never disclosed.....

And to your last comment.. I can navigate perfectly without GPS, thank you....

 

[Witmo]

Maybe it's that commercial company that bought bandwidth near GPS freqs testing interference issues...

 

[MAKG1]

Personally I think the majority of these tests are nothing more then the guvs ability to impart doubt in the publics mind and to show their abilty to cause the GPS constallation to be disabled at their whim.. The guv seems to be able to give warnings but the reason for all the tests are never disclosed.....

And to your last comment.. I can navigate perfectly without GPS, thank you....

Yes, it's a government conspiracy to create doubt about the efficacy of its own navigation system. You figured it all out. We wouldn't want people to think the military can get anywhere specific now, do we?

The government could disable the constellation trivially by uploading wrong elements to the satellites or scrambling the times by a few seconds. No need for localized jamming.

Do you THINK before you post?

This is rather obviously a developing capability to make navigation to a specific spot difficult. That would be a defense against GPS guided munitions, so the other guys can't attack us while we can still attack them.

There is no strategic benefit to making your own citizens doubt your technology. Quite the opposite. If hearts and minds are the target, you want the population to think your technology is bulletproof to the point of magic.

 

[N801BH]

...... If hearts and minds are the target, you want the population to think your technology is bulletproof to the point of magic.

Just like the Obamacare website...

 

[gismo]

Yup, testing effects of terrain, foliage, etc., makes sense in the open ocean .... no, wait.

And everyone knows there aren't any aircraft out there. And lots of VORs and LORAN stations ....

Airliners rely on inertial nav and besides most of the testing is done near enough to an ocean to disrupt international traffic just as much as a mid ocean test (remember the range of the interference increases with altitude).

It's a whole lot cheaper to haul out your ground station and testing team into the middle of the ocean.

I never meant to imply that offshore testing wouldn't be more difficult or expensive, but it seems to me that the testers should bear the cost of the testing, rather than everyone else who depends on GPS. What do you suppose is going to happen in the future when ADS-B has replaced surveillance radar?

Might want to think this through a bit. Especially since pilots are supposed to be competent enough to navigate without a magic box.

I have thought it through. Deliberate GPS interference can have a significant impact on GA and IMO it's something that could and should be avoided.