How often does your GPS fail?

AlleyCat67

AlleyCat67

Pre-takeoff checklist
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AleyCat67
Over the last three months, I've had my GTN650 loose GPS signal twice in flight. In January it went out twice on on an IFR flight (each time for about 2-3 minutes). Last week, flying into KSAV VFR, it went out again (twice) for 2-3 minutes at a time. Both times it came back for the remainder of the flight.

I'll be taking it to the avionics shop to check the antenna and connections, but I'm also wondering if occasional non-NOTAM'd GPS drops are common? I don't want to spend K$ tracking an intermittent bug that's not actually a discrepancy.
 
The only time in ten years that I've noticed an interruption was when they did interference testing nearby.
 
I’ve never seen it in my GNC 300xl in almost 20 years of operation. That’s not to say it can’t happen in some areas due to radio interference. If it happens you should report it to the nearest ATC facility or preferably FSS as they will better know how to handle the report. If enough complaints happen the FAA and FCC will investigate.
 
Never experienced an outage of any kind in a panel mounted navigator. The only problem I ever had of any kind was years ago when trying to wiggle under the DFW Bravo veil my iPad went away from Foreflight. Turned out it was a power cable or something that actuated the touchscreen.

in your case, I wonder if you have an intermittent antenna connection.
 
MBDiagMan said:
Never experienced an outage of any kind in a panel mounted navigator. The only problem I ever had of any kind was years ago when trying to wiggle under the DFW Bravo veil my iPad went away from Foreflight. Turned out it was a power cable or something that actuated the touchscreen.

in your case, I wonder if you have an intermittent antenna connection.
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Yes... the fact that I had no outages for 2 years, and then 2 within a few months is pointing to some new issue. Good to hear that outages are rare/unheard of for most people. I was flustered enough when it happened that I didn't run the GPS diagnostics on the 650, eg. to check for number of satellites in view.
 
If your EFB or portable GPS did not hiccup, it seems likely that the issue is with the GTN and/or its antenna and not the GPS signal. My GNS-430 had a GPS hiccup (while the portable GPS and my EFB soldiered on), and subsequently mysteriously lost the ability to ever establish LPV integrity. Other than the inability to arm an LPV, there were no integrity flags, and it could fly a GPS route or LNAV approach just fine. The cause of the anomaly was a failure of the vertical guidance board, which had to be replaced. Other than this one internal failure, I have NEVER seen the GNS-430 lose GPS integrity, even during periods where possible GPS interference was scheduled.
 
The school I teach at has two different planes that consistently loose GPS coming back into the field (a 430 in one and a 530 in the other). I’d say 80% of the time it gives me “no gps position” for about a minute when we’re 5-7 miles out. Just enough to mess with IFR training.

My club plane (at a different airport) had no issues the last time I brought it to the school’s airport.

Odd that two different planes would have the same issue.


Sent from my iPhone using Tapatalk
 
As an update (in case it’s helpful to others) the culprit was my old Narco ELT. Transmissions from my 650 Com1 excited RF from the ELT, harmonics of which drowned out the GPS. Pretty common issue - but not one I was aware of. A new ELT was the so.union.
 
AlleyCat67 said:
Over the last three months, I've had my GTN650 loose GPS signal twice in flight. In January it went out twice on on an IFR flight (each time for about 2-3 minutes). Last week, flying into KSAV VFR, it went out again (twice) for 2-3 minutes at a time. Both times it came back for the remainder of the flight.

I'll be taking it to the avionics shop to check the antenna and connections, but I'm also wondering if occasional non-NOTAM'd GPS drops are common? I don't want to spend K$ tracking an intermittent bug that's not actually a discrepancy.
Click to expand...
After I installed my GTN 650 in 2017, it was losing signal every 10 minutes. Then it didn't for a couple of flights, then it happened again.

Long story short, the culprit was my Spot. I had it on my panel, just under where the WAAS antenna was mounted on my roof, and when it sent out its burst every 10 min, it caused just enough interference (only 18" or so from the antenna) that my GTN decided it has lost integrity from the satellites. The flights when I had no problem were the flights when I hadn't brought the Spot.

I gave my Spot to my brother-in-law to use on motorcycle rides, and haven't had a problem in almost 4 years since (except for an actual, NOTAM'd GPS outage). It probably also would have been OK further from the antenna, e.g. back in the baggage area.
 
David Megginson said:
After I installed my GTN 650 in 2017, it was losing signal every 10 minutes. Then it didn't for a couple of flights, then it happened again.

Long story short, the culprit was my Spot. I had it on my panel, just under where the WAAS antenna was mounted on my roof, and when it sent out its burst every 10 min, it caused just enough interference (only 18" or so from the antenna) that my GTN decided it has lost integrity from the satellites. The flights when I had no problem were the flights when I hadn't brought the Spot.

I gave my Spot to my brother-in-law to use on motorcycle rides, and haven't had a problem in almost 4 years since (except for an actual, NOTAM'd GPS outage). It probably also would have been OK further from the antenna, e.g. back in the baggage area.
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Just saw your later post. Same idea as my Spot problem. GPS satellite signals are very low-power, and it doesn't take much to interfere with them.
 
I want you guys to know that this thread has jinxed me! I never experienced an inflight problem of any kind until making that statement in this thread.

After picking up my 140 at the avionics shop where it was in for a 420 installation,I had an overheat warning on the Foreflight in my lap. It was VFR an I could have made it home with no nav aids of any kind because I know the lakes and it wasn’t a GPS loss like discussed in the OP, but it was the first problem I can member. BTW, it never quit, it only gave a warning that it may overheat.
 
MBDiagMan said:
I want you guys to know that this thread has jinxed me! I never experienced an inflight problem of any kind until making that statement in this thread.

After picking up my 140 at the avionics shop where it was in for a 420 installation,I had an overheat warning on the Foreflight in my lap. It was VFR an I could have made it home with no nav aids of any kind because I know the lakes and it wasn’t a GPS loss like discussed in the OP, but it was the first problem I can member. BTW, it never quit, it only gave a warning that it may overheat.
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Well, glad I could help... I often bring that kind of luck!
 
MBDiagMan said:
I want you guys to know that this thread has jinxed me! I never experienced an inflight problem of any kind until making that statement in this thread.

After picking up my 140 at the avionics shop where it was in for a 420 installation,I had an overheat warning on the Foreflight in my lap. It was VFR an I could have made it home with no nav aids of any kind because I know the lakes and it wasn’t a GPS loss like discussed in the OP, but it was the first problem I can member. BTW, it never quit, it only gave a warning that it may overheat.
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@MBDiagMan's story shows why it's a good idea to practice the old pilotage and dead-reckoning techniques once in a while to keep in practice, especially in case you're over not over familiar territory when it happens. Besides, it's fun.
 
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Well David, I guess I can’t win for losing. In another lengthy thread on a related subject I was widely chastised because I keep charts within reach just in case of something like this. In the case of my experience last week, the 420 was at hand had I been in unfamiliar territory. I consider myself proficient with pilotage since I learned to fly in ‘92 and occasionally practice for fun.
 
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David Megginson said:
Long story short, the culprit was my Spot. I had it on my panel, just under where the WAAS antenna was mounted on my roof, and when it sent out its burst every 10 min, it caused just enough interference (only 18" or so from the antenna) that my GTN decided it has lost integrity from the satellites. The flights when I had no problem were the flights when I hadn't brought the Spot.
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Holy crap... man, I hope you just broke the code on my intermittent GNX 375 in my RV-8! I installed it last year, but it's always been glitchy in that it will randomly lose the GPS signal for 5-15 seconds, then reacquire. I've checked the antenna cable and swapped in a new known antenna, but the behavior remains. The Spot tracker, now that's a new variable! I always have it on and pinging and the antennas are maybe 3 feet apart. Next flight, the Spot tracker stays off and I'll cross my fingers...
 
Now that I'm doing partial panel for IR training things are failing in my plane all the time. ;)
 
jbDC9 said:
Holy crap... man, I hope you just broke the code on my intermittent GNX 375 in my RV-8! I installed it last year, but it's always been glitchy in that it will randomly lose the GPS signal for 5-15 seconds, then reacquire. I've checked the antenna cable and swapped in a new known antenna, but the behavior remains. The Spot tracker, now that's a new variable! I always have it on and pinging and the antennas are maybe 3 feet apart. Next flight, the Spot tracker stays off and I'll cross my fingers...
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I hope that's it! I just heard from a friend who had the same problem with a Spot and the GPS 175. For him, it was only about one out of three Spot bursts that caused the GPS to lose satellites.
 
MBDiagMan said:
Well David, I guess I can’t win for losing. In another lengthy thread on a related subject I was widely chastised because I keep charts within reach just in case of something like this. In the case of my experience last week, the 420 was at hand had I been in unfamiliar territory. I consider myself proficient with pilotage since I learned to fly in ‘92 and occasionally practice for fun.
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No criticism from me for either point. I agree with keeping the charts close to hand, and respect that you found your way home by pilotage. I thought it was worth reinforcing your point for all the anti-chart sceptics. I'll go back and edit my reply to make it clearer that it's neither personal nor a criticism.
 
texasclouds said:
Do you even VOR, bruh?
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If I'm "bruh," then yes, especially before I installed an IFR GPS 4 years ago, but I still keep in practice. I also still practice NDB navigation and approaches. Just having something in your panel doesn't help if you don't stay current with it.
 
Once in about 7 or 8 years. ForeFlight update had a glitch several years ago..dropped the gps after about 15 minutes..I continued on to the beach using my backup ipad..older program worked fine. Before FF, Garmin handhelds..no issues. No panel gps in my old C195..
 
I've never had a GPS fail. I did have a reboot many years ago when I flew off the end of the Charlotte sectional. Rebooting put me back on the magenta line on the Atlanta sectional. My iFly is continuous so that is an issue from the olden days ... :D
 
Never in my personal airplane. A few times in the military during training events and once in Iraq.
 
flyingron said:
My GPS has been more reliable than the VOR. In fact, the VOR is busted right now.
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I don't think anyone's arguing that VOR is better than GPS; just that you need to keep proficient with VOR for when GPS isn't there. Even if your local VOR is U/S, there are probably others you could receive in an emergency, when you're in IMC and there's an unplanned GPS outage.
 
Never had a gps fail

iPad overheated, yes, plenty of times. But that's just Apple crap

Never had a 430/530/650/750 G1K, KLN, TomTom, Samsung, Pixel, iPhone, hiking GPS.. etc "fail"

The OP's issue seems related to his installation and and not mass scale simultaneous failures of dozens of satellites

Coming back from AVX last weekend you should have seen how long the VOR unusable NOTAM list was. Thank goodness I had GPS!!

Mind you, a paper sectional won't help you over the water in 5 mile viz and haze
 
Tantalum said:
Never had a gps fail

iPad overheated, yes, plenty of times. But that's just Apple crap

Never had a 430/530/650/750 G1K, KLN, TomTom, Samsung, Pixel, iPhone, hiking GPS.. etc "fail"

The OP's issue seems related to his installation and and not mass scale simultaneous failures of dozens of satellites

Coming back from AVX last weekend you should have seen how long the VOR unusable NOTAM list was. Thank goodness I had GPS!!

Mind you, a paper sectional won't help you over the water in 5 mile viz and haze
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You mean the same way that an Attitude Indicator won’t help you navigate? A GPS won’t help you keep the shiny side up any more than a paper chart. I think your comparing oranges to apples.

The subject is whether or not you’ve ever experienced a GPS outage. Paper charts are a different subject.
 
The SPOT issue is real. Often, it can be solved by moving the SPOT just a foot or two. I’ve seen it with a Gen3 but never a SPOT X.
 
Had a problem after my shop replacee the antenna for my old 121.5 ELT. My 530w would lose GPS lock whenever I transmitted on a frequency between about 120.0 and 121.0 MHz Was an issue getting switched to tower (operating on a frequency in that range) on an RNAV approach, losing GPS signal, and having to go missed and fly a VOR approach.

As I understand what was happening from postings online, transmitting on those frequencies can cause the output circuit of those old ELTs to resonate at a frequency that is a harmonic of the GPS signal(s) and overload the GPS antenna. A GPS notch filter in the ELT coax did not control the problem. Apparently my old ELT antenna (which was not the proper one for my old ELT) was not subject to this behavior, as I never had the problem with the old antenna.

The solution was to replace the 121.5 ELT with a new 406 ELT. GPS has been solid since then.
 
MBDiagMan said:
You mean the same way that an Attitude Indicator won’t help you navigate? A GPS won’t help you keep the shiny side up any more than a paper chart. I think your comparing oranges to apples.

The subject is whether or not you’ve ever experienced a GPS outage. Paper charts are a different subject.
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I guess I just didn't understand the debate. A competent aviator should always know where they are. The GPS is a good easy tool that dramatically simplifies cockpit workload, but it doesn't remove the need to "navigate"

But this should be in that other thread

And maybe I'm alone.. didn't we have a post where someone couldn't fly a departure clearance because they couldn't (or didn't know how) to load a VOR radial into their garmin/autopilot? It's sad if we really do have people out there who solely rely on the GPS
 
bkspero said:
Had a problem after my shop replacee the antenna for my old 121.5 ELT. My 530w would lose GPS lock whenever I transmitted on a frequency between about 120.0 and 121.0 MHz Was an issue getting switched to tower (operating on a frequency in that range) on an RNAV approach, losing GPS signal, and having to go missed and fly a VOR approach.

As I understand what was happening from postings online, transmitting on those frequencies can cause the output circuit of those old ELTs to resonate at a frequency that is a harmonic of the GPS signal(s) and overload the GPS antenna. A GPS notch filter in the ELT coax did not control the problem. Apparently my old ELT antenna (which was not the proper one for my old ELT) was not subject to this behavior, as I never had the problem with the old antenna.

The solution was to replace the 121.5 ELT with a new 406 ELT. GPS has been solid since then.
Click to expand...

Yes - that was exactly the issue for me. And the new 406 ELT was the fix.
 
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