G1000 message - Abort approach, GPS signal lost

[Yariv]

Hi,

I did not take a picture of the alert so the wording may have been different but it should be close. I saw this alert yesterday during an IFR flight at cruise altitude before getting an approach clearance and decided to abort the flight. I told approach I saw an alert about GPS signal loss and that I would like to go back to Paine field and shoot the ILS approach. I received vectors back to Paine and as I turned around that alert was gone. It did not re-appear for the rest of the uneventful flight.

Have any of you seen a message similar to this on the G1000? I fly a 2004 Ovation 2GX.

Thank you,

Yariv

[LANCECASPER]

1 minute ago, Yariv said:

Hi,

I did not take a picture of the alert so the wording may have been different but it should be close. I saw this alert yesterday during an IFR flight at cruise altitude before getting an approach clearance and decided to abort the flight. I told approach I saw an alert about GPS signal loss and that I would like to go back to Paine field and shoot the ILS approach. I received vectors back to Paine and as I turned around that alert was gone. It did not re-appear for the rest of the uneventful flight.

Have any of you seen a message similar to this on the G1000? I fly a 2004 Ovation 2GX.

Thank you,

Yariv

I'm new to the G1000 but have not seen it yet in practice GPS approaches. What software do you have installed?

[Yariv]

Says software version is: 0401.34.

[buddy]

I have never seen that message and I believe I have the same software version.

[GeeBee]

Was there a GPS or WAAS NOTAM?

 

 

[takair]

Did you happen to transmit on the comm just prior to the event?  If so, which radio, what frequency?  There should be a satellite status page you can monitor that may help diagnose the issue.  Pay particular attention to it when transmitting on various frequencies.  It is rare in a well integrated package, but I have seen it, especially as antennas move around or equipment is added.

[PaulM]

Yes,  I have seen both... I have had a total GPS loss on an  airway flying IFR just south of the Washington DC area.   I just dialed in the VOR for the airway, switched the heading source and the GPS came back about 30 seconds later. 

I have also had it go LOI in the middle of a RNAV LPV approach, right when I was at the bottom of the cloud deck, so the runway was in sight.   

[Danb]

42 minutes ago, PaulM said:

Yes,  I have seen both... I have had a total GPS loss on an  airway flying IFR just south of the Washington DC area.   I just dialed in the VOR for the airway, switched the heading source and the GPS came back about 30 seconds later. 

I have also had it go LOI in the middle of a RNAV LPV approach, right when I was at the bottom of the cloud deck, so the runway was in sight.   

I’ve lost my GPS twice in the last month in the same area also for about a minute, just NE of Nashville must be a dead spot or something in that area.

[kortopates]

LOI errors with GPS are not that uncommon. I’ve found that in planes that it’s more frequent it’s often due to a poor coax/antenna connection.
Ditto on the above advice to check your satellite status page for signals. The other thing is to query ATC as to whether or not anyone else in your area is also seeing it. And if both GPS lost it or if a portable lost it as well. When not, despite other traffic, it’s time to investigate your installation for a loss of signal strength somewhere - usually between the antenna cable and antenna.


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[Yariv]

there were no GPS or WAAS NOTAMs, I don't think it coincided with radio transmission (I have not seen this message before), no new equipment was installed. I plan to check it again over the weekend and this time I will take some pictures.

Thanks for all the responses!

[Nick Pilotte]

My friend has seen this on a GPS approach into his home airport on his G1000 too.  The airport now has a NOTAM stating that approach is not in service and the ILS is to be used.  It appears there is something surface based 5 miles and 2 miles out that is disrupting the signals.  Because it’s an approach and under a Bravo shelf, I don’t know other implications.  

[hais]

On 1/19/2022 at 7:08 AM, PaulM said:

Yes,  I have seen both... I have had a total GPS loss on an  airway flying IFR just south of the Washington DC area.   I just dialed in the VOR for the airway, switched the heading source and the GPS came back about 30 seconds later. 

I have also had it go LOI in the middle of a RNAV LPV approach, right when I was at the bottom of the cloud deck, so the runway was in sight.   

Always wondered how one goes missed in that case - climb on same heading straight to MSA until vectored otherwise? Assume the missed approach does require GPS and there are turns involved.

[Nick Pilotte]

58 minutes ago, hais said:

Always wondered how one goes missed in that case - climb on same heading straight to MSA until vectored otherwise? Assume the missed approach does require GPS and there are turns involved.

In the case of the airport my friend is at, since it’s within a few miles of ORD, you climb to 1400, then immediate turn East.   Depending on the approach you get vectors out over the lake or back to OBK VOR.  Another pilot I know who experienced the loss of GPS into PWK before it was notam’d immediately loaded the ILS approach and continued on to break out 300’ AGL. 

[Boilermonkey]

Please report the incident at:  https://www.gps.gov/support/user/  follow the links for Aviation Civilian.

It's something that we track to see how GPS & WAAS perform in the real world.  Although, the most likely failures are usually equipment/cabling etc.

Occasionally it's jamming depending on your height AGL.

 

[Yariv]

I went to the airport today to check the GPS. Moved the airplane out of the hangar so it has view of the sky and turn the master switch on. 
i saw one of the errors from last week - “AHRS1 GPS - AHRS1 not receiving any GPS information”. This alert went a way after a few seconds. Attached are some images. I will report it in the link you provided above. Thanks

[PaulM]

14 hours ago, Yariv said:

“AHRS1 GPS - AHRS1 not receiving any GPS information”.

That is normal during startup.. The GPS hasn't got a full lock yet. 

[Boilermonkey]

That looks perfectly normal.  It takes a minute or so for the system to acquire the signals, compute a fix, and check integrity.  The constellation and signal strength show all of the visible satellites and strength.  The green ones are the ones that it is actively using.  As we fly through the sky and the satellites orbit the system will change which ones it uses.

 

If you have a failure in the future it would be great to get a pic of this status screen (workload permitting).  I'd also be interested if there is a difference between GPS1 and GPS in your system.  That might help determine if there are equipment issues (in particular the cables and antennas).

[Yariv]

I checked both GPS1 and GPS2 yesterday and both had about the same satellites captured. I am now more curious about the 2nd alert I got during the flight - Abort approach. The next time I fly (after Feb 1st) I will try to repro it by following the same track and loading the same approach. this time I will take a picture.

[Boilermonkey]

That will be interesting to recreate.  If there is interference from the surroundings, then it would reoccur and be something that could be looked into.   

[McMooney]

I get LOI's very very rarely on a GNS480.  Generally just wait a few seconds for the box to self correct.

I believe most of my LOI's were due to a missing filter on COM2.   having typed that, generally prepared to switch to other navigation if needed.

 

[Boilermonkey]

If possible cross check with other GPS systems.  I had a G430W and a L3/Lynx NGT9000 transponder.  I would occasionally loose GPS on the transponder, and it had a nice status page similar to the Garmin navigators.  I could see that when it failed it lost all the satellites.  Turned out to be a loose cable.

Look for the number of satellites and signal strength.  They should be similar, however, the "green" ones might be different based on what each devices chooses for it's position fix.   

You could also cross check with a Sentry/Stratus in Foreflight.   Or, even you phone's GPS.  Keep in mind their signal strength will be less since they are not externally mounted.

[Robert C.]

On 1/24/2022 at 11:11 AM, PaulM said:

That is normal during startup.. The GPS hasn't got a full lock yet. 

yep, I also get that on a regular basis.

[Boilermonkey]

Getting lock is pretty quick now a days.  Older GPS nav systems could take minutes to initialize and you couldn't taxi while initializing either.  Now it's usually a mater of seconds to a minute at most.

 

[Yariv]

I flew the same profile today and the abort approach alert did not display.