GPS Interference

[dans2992]

Has anyone ever actually seen anything strange due to all of those "GPS Interference Testing" notices that go out here in the west?

Any GPS anomalies?

Just troubleshooting a weird intermittent GPS issues and trying to understand the likelihood of this as a cause. Garmin 480.

 

[Fearless Tower]

I have seen it offshore, but not out near the NOTAM'd areas in the western US.

 

[Martymccasland]

Has anyone ever actually seen anything strange due to all of those "GPS Interference Testing" notices that go out here in the west?

Any GPS anomalies?

Just troubleshooting a weird intermittent GPS issues and trying to understand the likelihood of this as a cause. Garmin 480.

Do you have an old 121.5 ELT? If so, try completely disconnecting it AND turning it off.

 

[dans2992]

No, we upgraded to 406 about a year ago.

Tried to reproduce the issue yesterday, but couldn't. Reported issue is "twitching" of the CDI and flag on the HSI, _only_ during GPS approaches, not during "enroute" mode. Haven't seen it myself, just going on what my partners have observed.

 

[azure]

Is it always at a specific airport? GPS interference isn't necessarily due to gov't testing. We have a joker with a (apparently) mobile jammer, thanks to which GPS signals are "unreliable" at PTK and sometimes over northern suburbs of Detroit. Has yet to happen to me in IMC, but I had an occurrence a couple of weeks ago (VFR) as I was leaving the area for a fly-in. As far as I know they have yet to catch the guy. But the symptom is usually complete loss of satellites, not partial loss of integrity.

edit: I just noticed you said you had a 480, as do I. In that case the loss of integrity should be annunciated. If the only sign is misbehavior of the HSI, I wonder if the problem has anything to do with GPS reception.

 

[dans2992]

Is it always at a specific airport? GPS interference isn't necessarily due to gov't testing. We have a joker with a (apparently) mobile jammer, thanks to which GPS signals are "unreliable" at PTK and sometimes over northern suburbs of Detroit. Has yet to happen to me in IMC, but I had an occurrence a couple of weeks ago (VFR) as I was leaving the area for a fly-in. As far as I know they have yet to catch the guy. But the symptom is usually complete loss of satellites, not partial loss of integrity.

edit: I just noticed you said you had a 480, as do I. In that case the loss of integrity should be annunciated. If the only sign is misbehavior of the HSI, I wonder if the problem has anything to do with GPS reception.

I'm thinking it could be something with the HSI as well. I've flown 2 GPS approaches this week and no problems with either, so it's apparently intermittent.

 

[ARFlyer]

It's extremely easy to jam GPS signals as they are barely above the "noise" floor. All you need to do is produce a "louder" signal at or nearby the GPS signal frequency.