Lost GPS While on RNAV Approach in IMC

jsstevens said:
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.
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Do you have any specifics on how you'd use an iPad/iPhone if the panel GPS RAIM's/FDE's out? I think for me in IMC off the top of my head (subject to change since I haven't fully hashed everything out yet):
  • Alert me to nearby terrain: yes
  • Keep me out of the terrain: no
  • Get me to an airway: yes
  • Keep me on an airway: no
  • Navigate to a fix: no
  • Get me to a terminal area: yes
  • Descend below MSA in a terminal area: no
  • Navigate to IAF: no
 
For me it would depend on what alternatives were available.
 
And other variables like am I low on fuel?
 
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.

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.
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Foreflight has some way of knowing how accurate the GPS signal may be.
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.

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.
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Foreflight has some kind of way of knowing how accurate it thinks the GPS Signal is, including that it may not be getting a GPS Signal.

upload_2022-11-3_5-29-45.png

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That's pretty good, for a toy.
 
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.
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It was El Paso where I had my GPS outage, as well. Was somewhat near the Restricted area for the Aerostat.

I had the VOR dialed in for the airway, as a backup, so it was somewhat a non-event. But the big-guys were complaining.
 
I had degrade GPS signal once when flying over Louisiana / Gulf Coast in IMC.
My Aera 660 stared barking “sink rate sink rate” and then “Terrain , Pull up”. My altimeter was steady at 8,000ft over the coastline, so I figured I was safe from hitting anything. My 430w was not affected. Turned off all portable electronics and restarted the 660 but the problem still persisted for several minutes.

I’ve worked with GPS nav systems alot, and in my experience if GPS signals are degraded, the vertical precision (elevation) is usually the first to go.

I agree with other cautions given here, that the iPad can appear to have a location fix but could be dangerously misleading. If it doesn’t get gps, it can sometimes place you at the location of a cellphone tower, And then also sometimes use nearby known WiFi SSID’s to geolocate, all of which appear to give a location but could be off by a few blocks. Seen it happen several times on my iPad /iPhone when In a dense city (tall buildings block GPS)
 
BTW, I've had Foreflight crash while flying an approach in IMC. And yes, it was Foreflight itself, not the iPad or any GPS feed to it.
 
Did you call out Pan Pan? :)
 
Palmpilot said:
:hairraise:l
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LOL. Not that big a deal. I switched to my backup app and pulled up the chart.

Aside from that, the approach was already loaded so lateral was a non-issue. And while I was flying a 530 and steam gauges (no vertical prompts), it was a vectored approach to an ILS. Ceilings were well above mins so DA/MDA we're not a concern.

I was giving an IPC when the pilots iPad overheated and shut down. That was much more fun :devil::devil: but still handleable. I love when that happens (during training).
 
midlifeflyer said:
LOL. Not that big a deal. I switched to my backup app and pulled up the chart.

Aside from that, the approach was already loaded so lateral was a non-issue. And while I was flying a 530 and steam gauges (no vertical prompts), it was a vectored approach to an ILS. Ceilings were well above mins so DA/MDA we're not a concern.

I was giving an IPC when the pilots iPad overheated and shut down. That was much more fun :devil::devil: but still handleable. I love when that happens (during training).
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My reaction was predicated on the difficulty a pilot would be in without a backup source of charts, on a approach that had stepdowns. I guess even that wouldn't be a big deal on a G1000 though, since it displays stepdown altitudes.
 
Palmpilot said:
My reaction was predicated on the difficulty a pilot would be in without a backup source of charts, on a approach that had stepdowns. I guess even that wouldn't be a big deal on a G1000 though, since it displays stepdown altitudes.
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There's a few navigators/FMS boxes that will show these. But even without that there are options. That was the topic of discussion when my trainee's iPad overheat. He has a 430. He usually carries a backup but didn't have it that day, so it was a great, self-imposed training scenario.
 
ChopAndDrop said:
I had degrade GPS signal once when flying over Louisiana / Gulf Coast in IMC.
My Aera 660 stared barking “sink rate sink rate” and then “Terrain , Pull up”. My altimeter was steady at 8,000ft over the coastline, so I figured I was safe from hitting anything. My 430w was not affected. Turned off all portable electronics and restarted the 660 but the problem still persisted for several minutes.

I’ve worked with GPS nav systems alot, and in my experience if GPS signals are degraded, the vertical precision (elevation) is us
I agree with other cautions given here, that the iPad can appear to have a location fix but could be dangerously misleading. If it doesn’t get gps, it can sometimes place you at the location of a cellphone tower, And then also sometimes use nearby known WiFi SSID’s to geolocate, all of which appear to give a location but could be off by a few blocks. Seen it happen several times on my iPad /iPhone when In a dense city (tall buildings block GPS)
Click to expand...
Using my iPad with FF, but don't have the cell enabled iPad - I've used a Dual GPS with FF in the past, and a Sentry now. And my Android phone as a hot spot when needed. I had one experience with a G530 loosing signal - the iPad soldiered on and APPEARED to be telling the truth - I was VFR at the time - and clearly the iPad/FF were not relying on cell towers. since my iPad doesn't have the cell hardware.
 
Sundancer said:
...and clearly the iPad/FF were not relying on cell towers. since my iPad doesn't have the cell hardware.
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Not sure what you mean by "cell hardware" or cell towers" in this context. I presume you mean the iPad without the cellular option does not have a built-in GPS receiver.

I won't comment further because I am the toy boy.
 
POA boy toy? You have a calendar pictorial?
 
aterpster said:
Not sure what you mean by "cell hardware" or cell towers" in this context. I presume you mean the iPad without the cellular option does not have a built-in GPS receiver.

I won't comment further because I am the toy boy.
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Oh, an earlier post mentioned the cellular equipped iPads with built-in GPS may be using cell towers to augment location/position info when the GPS signal is shaky, perhaps making the position displayed less reliable - that wouldn't be apparent to the FF user.
 
Sundancer said:
Oh, an earlier post mentioned the cellular equipped iPads with built-in GPS may be using cell towers to augment location/position info when the GPS signal is shaky, perhaps making the position displayed less reliable - that wouldn't be apparent to the FF user.
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All cellular equipped ipads do have a built in gps. You are not obligated to subscribe to a cellular service provider in order to access the internal gps in the ipad. I have used these for years with FF. There is an instrument on the FF screen that keeps you informed as to gps accuracy...usually 5 meters or better using internal gps. If I connect to Stratus, I get even better accuracy.
 
Doug Reid said:
All cellular equipped ipads do have a built in gps. You are not obligated to subscribe to a cellular service provider in order to access the internal gps in the ipad. I have used these for years with FF. There is an instrument on the FF screen that keeps you informed as to gps accuracy...usually 5 meters or better using internal gps. If I connect to Stratus, I get even better accuracy.
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Very aware, and I bought my iPad expressly without cellular capability - I prefer en external GPS source; my old dual had a nice add-on app that gave a decent indication of GPS status, though without RAIM monitoring. Using a Sentry now.
 
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