Lost GPS While on RNAV Approach in IMC

WDD

WDD

Final Approach
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Vintage Snazzy (so my adult children say)
That was fun. Was doing my monthly “keep current” training with my CFII when that happened when we were established on an RNAV approach.

For some strange reason I remembered training - go figure. Situation was stable so don’t act immediately - think it out. Held altitude and heading. We were before the FAF and switched to tower, so quick call to tower to tell them we had lost the GPS and might need to do something different.

Decided plan of action was to go back to approach and ask to get back up to VMC altitude, get delaying vectors, and find an alternative with ILS and get vectors to final.

In the end it was anticlimactic. The GTN GPS came back on line, called tower we were continuing approach, cleared to land and we popped out to VMC and I made actually a decent landing.

Something quirky with the 650. Called our club maintenance officer to have him get it looked at.

I have a new appreciation for redundancy and backup systems!
 
The GTN GPS cable connects to the tray with a screw on male TNC connector. It isn't the BNC type like the 430's have. Might check its screwed on tight at the tray.
 
Thanks - I’ll pass that to the clubs maintenance officer.
 
WDD said:
Didn’t lose gps on my tablet, so it wasn’t a GPS signal problem.
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Just FYI.

Was departing El Paso one afternoon and pretty shortly lost signal on both my 430 and 530. My iPad was still getting a signal and showing my position and speed, etc.

I was annoyed thinking about how I was going to troubleshoot this 430/530 issue and how much money it was going to cost. Until I started hearing airliners asking about GPS signal loss. My GPS signal on the 430/530 came back right about where ATC said it would.

So, I guess what I'm saying is that just because your tablet still had signal, doesn't mean there wasn't a GPS signal problem.
 
I relatively often lose GPS around this area, it's plane agnostic and there are a few "hotspots" where I always tend to lose it.. such as the RNAV 17 into SEE, and on short final to HND. Oddly, this only impacts the ship's GPS and never my Stratus, iPhone, etc.

(A) great to have backup
(B) I've never lost an ILS or LOC signal, but have many times lost GPS, because of this I always ask for the ILS
 
I was unable to receive the SJC glideslope once. Pretty sure it was the equipment in the plane I was flying, because Tower said they had not had any other reports of trouble.
 
dans2992 said:
Something else to keep in mind - iPad/iPhone also use Galileo/GLONASS and other GPS-like networks. Aviation units might not.
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Is Galileo/GLONASS accuracy comparable to GPS? They don't have WAAS-like correction, right?

And if the GPS jammer is Russia, what do you think will happen to GLONASS? :)
 
asicer said:
Is Galileo/GLONASS accuracy comparable to GPS? They don't have WAAS-like correction, right?

And if the GPS jammer is Russia, what do you think will happen to GLONASS? :)
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That's not how GPS jamming works. You can't jam GPS without jamming GLONASS, since they share the same frequencies/band.

It's also worth noting that portable devices (iPhone, iPad, etc) are significantly more forgiving of GPS issues/inaccuracies. Certified GPS (GTN in this case) will drop out and report an issue much sooner than Foreflight will.
 
jrcox19 said:
It's also worth noting that portable devices (iPhone, iPad, etc) are significantly more forgiving of GPS issues/inaccuracies. Certified GPS (GTN in this case) will drop out and report an issue much sooner than Foreflight will.
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I wouldn't characterize it as "forgiving." The GPS "toy" is clueless about integrity requirements for IFR-certified devices.
 
aterpster said:
I wouldn't characterize it as "forgiving." The GPS "toy" is clueless about integrity requirements for IFR-certified devices.
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It worked when the certified didn’t. I wouldn’t put it in the toy category.
 
WDD said:
It worked when the certified didn’t. I wouldn’t put it in the toy category.
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You apparently don't understand integrity and continuity, as it applies to IFR avionics. (and doesn't apply to consumer GPS gadgets.)
 
aterpster said:
You apparently don't understand integrity and continuity, as it applies to IFR avionics. (and doesn't apply to consumer GPS gadgets.)
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I do. But if the certified unit goes off line, I’m going to use what I have left - including the tablet. I’m using it as part of what I have left - not flying the approach based only on it.

My humble opinion - I don’t consider ForeFlight and IFly running on a tablet a toy. But your opinion may differ - all good.
 
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asicer said:
It fooled you into thinking that it worked. ;)
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aterpster said:
You apparently don't understand integrity and continuity, as it applies to IFR avionics. (and doesn't apply to consumer GPS gadgets.)
Click to expand...

Yup, real easy to get sucked into confirmation bias when one of the magic boxes still “appears” to work. I’ve had my phone GPS glitch out on me too many times and show false locations, to trust it over certified equipment failing integrity. It’s a tool in the bag in case SHTF and I lose electrical or something, but not as a replacement when I have reliable indications of a bad signal in IMC
 
iPads / phones also use cell tower and wifi to "guess" gps information. I would not use that to fly an approach with, or even to determine MSA.
 
WDD said:
My humble opinion - I don’t consider ForeFlight and IFly running on a tablet a toy. But your opinion may differ - all good.
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FF as an app is not a toy. The GPS in an iPad IS a toy. It's a fact. Not my opinion. Read the RTCA docs if you like.

EDIT: FF as a flight planning and performance tool is not a toy. As a navigator it IS a toy.
 
aterpster said:
FF as an app is not a toy. The GPS in an iPad IS a toy. It's a fact. Not my opinion. Read the RTCA docs if you like.

EDIT: FF as a flight planning and performance tool is not a toy. As a navigator it IS a toy.
Click to expand...

Toy
  1. An object for a child to play with.
  2. Something that provides amusement.
  3. A small ornament; a bauble.
  4. Something of little importance; a trifle.
  5. A diminutive thing, especially a dog of a very small breed or of a variety smaller than the standard variety of its breed.
  6. A loose covering for the head, formerly worn by women.
  7. A shooter marble.
I would say it doesn't fall into any of those definitions.
 
WDD said:
Didn’t lose gps on my tablet, so it wasn’t a GPS signal problem.
Click to expand...

to piggyback, as far as I know no non TSO’d non IFR GPS has RAIM/FDE. So although there might be some GPS signal, your tablet wouldn’t be able to tell you the quality of that signal to the degree to be safe on an approach. I’m sure that’s a big reason as to why there are no IFR certified portable devices. I’d use my tablet as a backup for enroute navigation but never for an approach. This is why I advocate keeping a nav radio in the panel (especially for guys building new planes or upgrading panels)—to give you options.
 
EdFred said:
Toy
  1. An object for a child to play with.
  2. Something that provides amusement.
  3. A small ornament; a bauble.
  4. Something of little importance; a trifle.
  5. A diminutive thing, especially a dog of a very small breed or of a variety smaller than the standard variety of its breed.
  6. A loose covering for the head, formerly worn by women.
  7. A shooter marble.
I would say it doesn't fall into any of those definitions.
Click to expand...
Whatever.
 
tsts4 said:
to piggyback, as far as I know no non TSO’d non IFR GPS has RAIM/FDE. So although there might be some GPS signal, your tablet wouldn’t be able to tell you the quality of that signal to the degree to be safe on an approach. I’m sure that’s a big reason as to why there are no IFR certified portable devices. I’d use my tablet as a backup for enroute navigation but never for an approach. This is why I advocate keeping a nav radio in the panel (especially for guys building new planes or upgrading panels)—to give you options.
Click to expand...

I’ve had a TSO’ed/certified Garmin GPS antenna start to delaminate internally. The failure was intermittent, but when it happened, it jammed all other GPS devices onboard! Approaching mins in IMC is not a time for such “random” failures. iPads don’t do that (they have issues, sure, but each has its place).
 
dans2992 said:
I’ve had a TSO’ed/certified Garmin GPS antenna start to delaminate internally. The failure was intermittent, but when it happened, it jammed all other GPS devices onboard! Approaching mins in IMC is not a time for such “random” failures. iPads don’t do that (they have issues, sure, but each has its place).
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Don’t disagree, but tablets aren’t the panacea as you can’t load approach on a tablet unless you do it manually (we’ll skip the legalities of doing so assuming this is an extreme emergency situation) and as you said approaching mins in IMC would be an extraordinarily bad time to try and roll your own approach. I’d use it to navigate to VFR conditions or better yet transition to an approved alternate means of IFR navigation. YMMV…
 
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tsts4 said:
Don’t disagree, but tablets aren’t the panacea as you can’t load approach on a tablet unless you do it manually (we’ll skip the legalities of doing so assuming this is an extreme emergency situation) and as you said approaching mins in IMC would be an extraordinarily bad time to try and roll your own approach. I’d use it to navigate to VFR conditions or better yet transition to an approved alternate means of IFR navigation. YMMV…
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100%…. NOT advocating flying an approach with an iPad, although I suspect 99.9% of the time it would be fine…. That 0.1% will bite you eventually though. ;)
 
EdFred said:
So which one is it? Or are we just making up our own definitions of words?
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I'd say his intended meaning was a combo of #2 and #4, but you know that already.
 
tsts4 said:
to piggyback, as far as I know no non TSO’d non IFR GPS has RAIM/FDE. So although there might be some GPS signal, your tablet wouldn’t be able to tell you the quality of that signal to the degree to be safe on an approach. I’m sure that’s a big reason as to why there are no IFR certified portable devices. I’d use my tablet as a backup for enroute navigation but never for an approach. This is why I advocate keeping a nav radio in the panel (especially for guys building new planes or upgrading panels)—to give you options.
Click to expand...

Agree - don’t use F Flight to fly an approach. Will use it with everything else I still have left to get out of the situation and do something else. In this case it would have been to get vectors to KFTY which has an ILS on a runway compatible with the current wind.


(See my original post about what we were planning on doing).
 
iPad's and their ilk will "dead reckon" quite a long way to emulate GPS service when they don't have it rather than report it lost.

I just came back from a couple of weeks in Maine. The B&B we stayed at warned us not to use the GPS to find the Inn as it couldn't. In our case it did, but it got very confused as to exactly where we were and even which way we were going a number of times. Did it report GPS issues? Nope. But it clearly was estimating where it thought we might be. Often for a few minutes before it "found" us (likely got the GPS back).

Use the tools you have as you need them but understand where they might not be working-even if they don't SAY they're not working.
 
Sluggo63 said:
Just FYI.

Was departing El Paso one afternoon and pretty shortly lost signal on both my 430 and 530. My iPad was still getting a signal and showing my position and speed, etc.

I was annoyed thinking about how I was going to troubleshoot this 430/530 issue and how much money it was going to cost. Until I started hearing airliners asking about GPS signal loss. My GPS signal on the 430/530 came back right about where ATC said it would.

So, I guess what I'm saying is that just because your tablet still had signal, doesn't mean there wasn't a GPS signal problem.
Click to expand...

We get a lot of "GPS Outage NOTAMS" in my area that are not assigned to a specific field and can be a pain checking. Luckily a 273* heading westbound and 93* heading eastbound will basically make a line between El Paso-Austin. The VORs are also a little unreliable out here ...
 
danhagan said:
We get a lot of "GPS Outage NOTAMS" in my area that are not assigned to a specific field and can be a pain checking. Luckily a 273* heading westbound and 93* heading eastbound will basically make a line between El Paso-Austin. The VORs are also a little unreliable out here ...
Click to expand...
It’s all dead reckoning backed up by avionics until the runway shows up in front of you anyway.
 
WDD said:
That was fun. Was doing my monthly “keep current” training with my CFII when that happened when we were established on an RNAV approach.

For some strange reason I remembered training - go figure. Situation was stable so don’t act immediately - think it out. Held altitude and heading. We were before the FAF and switched to tower, so quick call to tower to tell them we had lost the GPS and might need to do something different.

Decided plan of action was to go back to approach and ask to get back up to VMC altitude, get delaying vectors, and find an alternative with ILS and get vectors to final.

In the end it was anticlimactic. The GTN GPS came back on line, called tower we were continuing approach, cleared to land and we popped out to VMC and I made actually a decent landing.

Something quirky with the 650. Called our club maintenance officer to have him get it looked at.

I have a new appreciation for redundancy and backup systems!
Click to expand...
I have a 750 and I back up my RNAV approaches with a VOR approach if available. Tune the VOR and start the clock at the FAF And if the GPS signal goes out on the way in just descend to the VOR MDA and complete that approach. Not always an option anymore but it’s a good plan if a VOR, LOC approach etc is available.
 
jsstevens said:
iPad's and their ilk will "dead reckon" quite a long way to emulate GPS service when they don't have it rather than report it lost
Click to expand...
Radio signal triangulation off of cell phone towers assisting the geolocation features of the phone is probably a lot less dead reckoning than it is science, honestly. My guess is that it’s probably a reasonably *good* backup in all honesty.
 
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RyanShort1 said:
Radio signal triangulation off of cell phone towers assisting the geolocation features of the phone is probably a lot less dead reckoning than it is science, honestly. My guess is that it’s probably a reasonably *good* backup in all honesty.
Click to expand...
Cell phone towers weren't really designed to talk to airborne targets traveling at triple digit speeds, so the quality of the result is a bit unknown.
 
RyanShort1 said:
Radio signal triangulation off of cell phone towers assisting the geolocation features of the phone is probably a lot less dead reckoning than it is science, honestly. My guess is that it’s probably a reasonably *good* backup in all honesty.
Click to expand...
No doubt triangulation from cell towers is science and math, but it's clear to me from the behavior that they're not using that to advantage in some cases either (weak signals, bounce, etc.). They do (depending on software, I'm sure) assume you are continuing the direction you last were or just have no idea without any warning that this position is "estimated". And that's the rub. Tell me you're guessing.

Would I use an iPad/iPhone for location if the other stuff goes off line? Yes, it's better than nothing. Would I trust it if the certified GPS unit says there's an outage? I'd really rather not.
 
In my case it wasn’t a GPS outage but a temporary equipment failure. I was still pinging ADSB in.

I remember asking my IFR DPE about this. His response was something to the effect of “bless your heart - yes, use everything you’ve got left”.

Really agree with the post made by JSStevens. Use what you have and keep in mind its limitations. (Something like that)
 
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Jamming is done at the point of reception, by drowning out the incoming signal with a stronger signal of the same frequency. Effective range is limited by physical location and transmitter power, since radio waves weaken as they propagate. Even military grade jamming is limited a relatively small radius around the emitter. The Russians cannot jam US locations from Russia. They cannot even jam their own positions in Ukraine sufficiently to prevent HIMARS and GPS artillery shells from hammering them.

But cheapo Chinese jammers are apparently a lot more available than one might expect. https://gizmodo.com/jamming-gps-signals-is-illegal-dangerous-cheap-and-e-1796778955

Because jammers put out a distinct signal, they are easy to detect and locate. So it is not something that can be done clandestinely for very long.
 
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