GPS intermittent

[aviatoreb]

Darn - my GPS seems to be intermittent.

GTN650 original not txi.

It boots up sometimes acquires a signal sometimes does not.  Sometimes when it acquires a signal it looses it after a few minutes.  When it doesn't have a signal it says no gps - and the page that shows the individual satellites its tracking is empty.  But the radio on it works and it shows a screen.

This has happened the last two flights which were local flights.

Mitigating confusion - I am in the hangar across from the air med company that they just told me that they have a gps repeater that they use for their own use of getting signal in their hangar but it can act as signal blocking for those near by?  SO could it be causing me to loose signal - even 10 mi away?  I never went more than 10 mi away on these two flights.

Couldn't be a data base or a software update thing can it?

Maybe its my antenna?  I guess I need to go to the avionics shop - in Burlington - but I already know what is going to happen - this is intermittent and it will work for them and they will tell me nothing is wrong.  :-?

[EricJ]

1 hour ago, aviatoreb said:

Darn - my GPS seems to be intermittent.

GTN650 original not txi.

It boots up sometimes acquires a signal sometimes does not.  Sometimes when it acquires a signal it looses it after a few minutes.  When it doesn't have a signal it says no gps - and the page that shows the individual satellites its tracking is empty.  But the radio on it works and it shows a screen.

This has happened the last two flights which were local flights.

Mitigating confusion - I am in the hangar across from the air med company that they just told me that they have a gps repeater that they use for their own use of getting signal in their hangar but it can act as signal blocking for those near by?  SO could it be causing me to loose signal - even 10 mi away?  I never went more than 10 mi away on these two flights.

Couldn't be a data base or a software update thing can it?

Maybe its my antenna?  I guess I need to go to the avionics shop - in Burlington - but I already know what is going to happen - this is intermittent and it will work for them and they will tell me nothing is wrong.  :-?

The range on repeaters is very short as they're only intended to bring the signal inside an enclosure (e.g., building) where the structure would otherwise attenuate the signal too much.    So you should be out of range of the repeater in a fairly short distance from the building.    It may affect your reception near their hangar, but it would be unlikely as you move away from their hangar.

And, yes, intermittent problems with anything can be difficult to sort out.   My IFD has a system log that is fairly easy to access that records events like that with related information that is often useful to help determine what's going on.    I suspect Garmin may do something similar.

[aviatoreb]

3 hours ago, EricJ said:

The range on repeaters is very short as they're only intended to bring the signal inside an enclosure (e.g., building) where the structure would otherwise attenuate the signal too much.    So you should be out of range of the repeater in a fairly short distance from the building.    It may affect your reception near their hangar, but it would be unlikely as you move away from their hangar.

And, yes, intermittent problems with anything can be difficult to sort out.   My IFD has a system log that is fairly easy to access that records events like that with related information that is often useful to help determine what's going on.    I suspect Garmin may do something similar.

I think you are right regarding the repeater - but I did go and talk to the guys in the hangar initially to see if they had experienced any recent locality gps blocking or something.  And that's when they told me about their repeater and how just the other day a helicopter had experience the issue right near their hangar on the ground - and I am across from them like 200 yards.

But...then once at the other end of the airport - or off the ground - or in the air ten mi away....

Ah - good point re a log.  Looks like I am taking a trip to an avionics shop soon.

[aviatoreb]

I cant find in my manual - does anyone know how to turn off and turn back on a GTN650 (cycle it) ?

[kortopates]

I cant find in my manual - does anyone know how to turn off and turn back on a GTN650 (cycle it) ?

The volume knob. there is also the CB too.

Look at the satellite page next time you have a reception issue.


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[aviatoreb]

I just read something on avweb:

https://www.avweb.com/aviation-news/solar-flares-unusually-strong-this-week/

Is anyone else having problems?  Maybe its the sun and not my airplane?  I quote:

Solar Flares Unusually Strong This Week

By

 Russ Niles

 -

Published: August 9, 2023Updated: August 10, 2023

2

If your GPS-driven panel functions seem glitchy this week the cause might be a Cannibal Coronal Mass Ejection (CME) and it’s as sinister as it sounds. The sun is reaching the end of Solar Cycle 25, 

[buddy]

Years ago I had the same problem (intermittent) in my M20J with the 530 and it was a bad antenna. Garmin sent a free replacement and I just had to pay for the labor. 

[aviatoreb]

3 hours ago, buddy said:

Years ago I had the same problem (intermittent) in my M20J with the 530 and it was a bad antenna. Garmin sent a free replacement and I just had to pay for the labor. 

Yeah - I bet that is what it is  -  that is exactly what the pilot at the medical lift company suggested - a bad antenna - and I am all geared up to go to my nearest friendly avionics shop...but after reading that article - I am going to fly today in any case and see what I see - it is a bit of a coincidence that the same week I had two occasions of intermittent for the first time - an article comes out in avweb that says solar flares are causing glitchy gps.

Anyone else?

[aviatoreb]

3 hours ago, kortopates said:

The volume knob. there is also the CB too.

Look at the satellite page next time you have a reception issue.


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What is CB?

Thanks,
E

[kortopates]

What is CB?
Thanks,
E

Circuit Breaker


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[Aerodon]

2 hours ago, aviatoreb said:

What is CB?

Thanks,
E

https://www.woxikon.com/abbreviations/en/cb, I see circuit breaker made the list, but Cheap Bastard did not.

[aviatoreb]

49 minutes ago, Aerodon said:

https://www.woxikon.com/abbreviations/en/cb, I see circuit breaker made the list, but Cheap Bastard did not.

I seem to be acronym challenged.

AC.

[aviatoreb]

Well I just flew again.  Still intermittent.

Pulled it out of the hangar - before startup test - gps signal acquired quickly. Turn off - Start up engine then restart panel - re-acquired quickly.

Begin flight - and what do you know - it lost signal again at almost the same spot and 3 miles east of the airport - so this time I head north about 20 miles and it re-acquires - I cycled the system twice - I am not sure if that helped.

Then on the way back - it lost signal again about 10 mi from home.  While the signal is good I have lots of gps satellites acquired - and when it is gone - none.

So then I am sure it is a bad antenna or something.  I land - and there is a medical lift company helicopter there from New Hampshire.

So - I talked to the helicopter pilot from Dartmouth U and asked if he’s had any gps issues and he said as a matter of fact yes he has, over the last week - in two different aircraft!

So now Im not sure what to think.  Im supposed to fly to Berlin, Maine tomorrow and current morning forecast past Burlington VT is marginal VFR - and there is terrain in that part - so more likely than not I will just stop in Burlington to visit the avionics shop and see if they can see me right away or rent a car from there - I want to get to the bottom of this.

Theory 1 - solar flares - supported by the article and the fact of the helicopter pilot having issues too in two different airplanes!
Theory 2 - antenna or something else comparable - supported by the fact of loosing it about 90 seconds into flight in two flights - suggesting it is vibration sensitive.

[EricJ]

45 minutes ago, aviatoreb said:

Well I just flew again.  Still intermittent.

Pulled it out of the hangar - before startup test - gps signal acquired quickly. Turn off - Start up engine then restart panel - re-acquired quickly.

Begin flight - and what do you know - it lost signal again at almost the same spot and 3 miles east of the airport - so this time I head north about 20 miles and it re-acquires - I cycled the system twice - I am not sure if that helped.

Then on the way back - it lost signal again about 10 mi from home.  While the signal is good I have lots of gps satellites acquired - and when it is gone - none.

So then I am sure it is a bad antenna or something.  I land - and there is a medical lift company helicopter there from New Hampshire.

So - I talked to the helicopter pilot from Dartmouth U and asked if he’s had any gps issues and he said as a matter of fact yes he has, over the last week - in two different aircraft!

So now Im not sure what to think.  Im supposed to fly to Berlin, Maine tomorrow and current morning forecast past Burlington VT is marginal VFR - and there is terrain in that part - so more likely than not I will just stop in Burlington to visit the avionics shop and see if they can see me right away or rent a car from there - I want to get to the bottom of this.

Theory 1 - solar flares - supported by the article and the fact of the helicopter pilot having issues too in two different airplanes!
Theory 2 - antenna or something else comparable - supported by the fact of loosing it about 90 seconds into flight in two flights - suggesting it is vibration sensitive.

FWIW, the FAA wants to know about GPS outages or anomalies, so it may be worth reporting if multiple people are seeing it or you're seeing it in a consistent geographic area.   Here:

https://www.faa.gov/air_traffic/nas/gps_reports

It sounds more likely that it is either an intermittent hardware failure, which may or may not be the case, or there is a local interference source that is disrupting reception.    The military and other agencies sometimes conduct jamming and jamming training/experimentation, and usually those are indicated in NOTAMs.   It's not unusual at all to see NOTAMs regarding gps availability, but usually they don't take the whole system down for the obvious safety issues.   If there is an interferer, that's a good reason to fill out the report for the FAA.

[201Mooniac]

Since it seems to happen in the vicinity of the airport, I had an issue once years ago where a certain range of frequencies tuned on my 430 would kill the GPS (it was the tower at a nearby airport if I remember correctly).  Turned out it was an issue with my ELT and had something to do with harmonics excited by the comm frequency.  The avionics shop installed a filter in the ELT antenna line and no problem since.  Though the 430 went out a few years ago now I presume a 650 could do the same at the same comm frequency.

[aviatoreb]

18 hours ago, EricJ said:

FWIW, the FAA wants to know about GPS outages or anomalies, so it may be worth reporting if multiple people are seeing it or you're seeing it in a consistent geographic area.   Here:

https://www.faa.gov/air_traffic/nas/gps_reports

It sounds more likely that it is either an intermittent hardware failure, which may or may not be the case, or there is a local interference source that is disrupting reception.    The military and other agencies sometimes conduct jamming and jamming training/experimentation, and usually those are indicated in NOTAMs.   It's not unusual at all to see NOTAMs regarding gps availability, but usually they don't take the whole system down for the obvious safety issues.   If there is an interferer, that's a good reason to fill out the report for the FAA.

Ill try that if I get another outage enough to think its area instead of my own hardware.  Thanks!

[aviatoreb]

So I just spoke to the avionics shop - they cant see me until next week - so I guess I get to play around with it until then on my own.

They did offer me yet another theory.  They asked me if I had dropped my cell phone recently.  Yes, as a matter of fact I have!  They said that if the rf shielding becomes dislodged it can really wreak havoc with your gps. HMMM!!  SO the suggestion is to test it with the cell phone on fully off mode.  Not just airplane mode.

[Joshua Blackh4t]

Interesting about the flares. I have had a gps related issue in the last few days flying.

My tailbeaconx was transmitting a location slightly different to my aera 660 was showing. Not a significant difference, but enough that the Aera didn't realise it was its own signal and started warning me of traffic. (I have a gdl39 to add adsb) The difference was so small that I couldn't tell which was wrong.

Hopefully it goes away, maybe the sun had something to do with it. 

Good luck. Electronics are annoying 

[aviatoreb]

Hello from Maine.

Well now I am thinking it is an area gps outage.  So for the 4th time in the past week, I lost GPS within 2 min of departure from home airport.  Looking back -I always turned eastward.  On two of the occasions, the first times, I then went home within just a few minutes assuming the equipment was broken and I wanted to debug it.  Third time I went North and found I could get it to come back a live by cycling it - so I thought - by about 15 mi north.  Then upon returning, it went out again.

Well today, same thing it went out within 2 min but it came back on its own - no recycling - within about 15 mi North East.  And stayed alive the rest of the way to Maine.  It had almost all satellites showing strong signal.

So now I suspect it may not be the airplane - but some kind of blocking going on to the immediate east of the airport.  Nefarious?  Military (we are 15 mi north of a MOA?). Solar flare?  UFO?

[Fly Boomer]

On 8/14/2023 at 8:52 PM, aviatoreb said:

Hello from Maine.

Well now I am thinking it is an area gps outage.  So for the 4th time in the past week, I lost GPS within 2 min of departure from home airport.  Looking back -I always turned eastward.  On two of the occasions, the first times, I then went home within just a few minutes assuming the equipment was broken and I wanted to debug it.  Third time I went North and found I could get it to come back a live by cycling it - so I thought - by about 15 mi north.  Then upon returning, it went out again.

Well today, same thing it went out within 2 min but it came back on its own - no recycling - within about 15 mi North East.  And stayed alive the rest of the way to Maine.  It had almost all satellites showing strong signal.

So now I suspect it may not be the airplane - but some kind of blocking going on to the immediate east of the airport.  Nefarious?  Military (we are 15 mi north of a MOA?). Solar flare?  UFO?

Got to be UFO.  Call Scully and Mulder.

[aviatoreb]

Hmmmm.... and now returned from Maine - everything working perfectly - I am more and more suspecting its not my panel and never was but it was GPS blocking.

[skykrawler]

It wouldn't be astonishing if there was someone on the ground with a defective radio transmitter or something emitting EMF that interfered with the GPS.

A second, perhaps handheld, GPS device might help in the diagnosis.  For that matter the cell phone probably has a GPS receiver.

 

[Ragsf15e]

17 hours ago, aviatoreb said:

Hmmmm.... and now returned from Maine - everything working perfectly - I am more and more suspecting its not my panel and never was but it was GPS blocking.

You have any hanger buddies that can fire up their avionics next to your plane and see if one works and one doesn’t?

[PT20J]

Here's an interesting site that has historical maps showing areas where ADS-B out from aircraft reported degraded GPS navigation accuracy.

www.gpsjam.org.

[Fly Boomer]

3 hours ago, PT20J said:

Here's an interesting site that has historical maps showing areas where ADS-B out from aircraft reported degraded GPS navigation accuracy.

www.gpsjam.org.

Took a bit just to find the US.  Then I couldn't find cities or states.