Losing GPS on approach

[Ed McDonald]

Are you using a PLB like SPOT?

We have used SPOT 3 and 4 with no issues but SPOT X caused a GPS dropout every time it sent a position report (breadcrumb trail).

[brian5x5]

Update: Diamond replaced both GPS antennas about 2 months ago and we haven't seen a single instance of the GPS dropping out since. Hopefully this has fixed the problem permanently. It's always hard to say when fixing an intermittent problem but this is by far the longest it has gone.

[Boatguy]

Diamond also issued an MSB two days ago regarding replacement of the now obsolete antenna installed in all Canadian built DA62's prior to C072. The new antenna supports VHF, GPS and Sirius XM and looks to be a little more stubby and perhaps less fragile.

Is this the antenna that was installed to resolve the failures cited in this thread?

[alanhawse]

Are you using a PLB like SPOT?

We have used SPOT 3 and 4 with no issues but SPOT X caused a GPS dropout every time it sent a position report (breadcrumb trail).

HO-LE-FUK!!! I bet this is what happened to me yesterday

Yesterday I flew from Nantucket back to Kentucky... I was on an instrument flight plan... just after I got to my assigned altitude I got a message from the Garmin which I had never seen about a loss of GPS data or something... I thought about it for a few minutes... then the GPS turned off, the Autopilot went into ROL,ALT mode and I lost the MFD maps and all of the ADS-B data.

I was highly highly not happy.... above the clouds and over the Atlantic ocean. I was trying to decide what to do next and the whole thing came back? Why? Who knows.

After I refueled at KUNV in Penn... I was sitting on the runway and got one message again.. for the last time.

As I thought about it I decided to turn off the Garmin InReach (the first time I ever really used it... and it never came back again.

My brain has been grinding on this ... scared shitless... and I just logged into to post if anyone had ever had something like this happen...

I bet that this is it.

Alan

[Boatguy]

Are you using a PLB like SPOT?

We have used SPOT 3 and 4 with no issues but SPOT X caused a GPS dropout every time it sent a position report (breadcrumb trail).

As I thought about it I decided to turn off the Garmin InReach (the first time I ever really used it... and it never came back again.

So one Garmin product temporarily disables another? Anyone contacted Garmin support about this?

*** added thought

Both Spot and the Garmin In Reach are transmitting to satellites. There are probably some EE's here who know the specific frequencies and could compare them to those used by the GPS system. GPS signals are pretty weak so I suspect with a bit of unintended frequency spread/splatter it doesn't take much to overwhelm the G1000 GIAs. Then the satellite devices stop transmitting, the GIAs take 1-2 minutes to connect to 4-5 GPS sats, and everything is fine again.

Newer iPhones can also transmit on satellite frequencies, but only upon request and presumably only in an emergency.

The key thing here would seem to be that there is nothing wrong with the G1000, wiring or antenna.

I've learned that 91.21 (a) prohibits portable electronic devices in 121/135 operations, and anyone operating under IFR. But then 91.21 (b)(2)(5) is a massive hole that says it's OK if it has been determined that the device does not cause interference with comms on the aircraft. So how would anyone know that, without trying it?

That said, it would seem that it has now been determined that portable satellite comm devices like Spot and InReach, do cause interference and are thus prohibited under 91.21.

[janders]

I just realized that when TX on a lower VHF frequency on COM1, the GPS2 signals drop completely. I was able to document the GPS drop in this video.

https://www.youtube.com/watch?v=az_fQOAr9_E

Perhaps, when on approach you switch to a tower frequency thats in this range and you get a GPS LOS.

[thommy152]

I’ve now experience multiple simultaneous failures of GPS 1 and GPS 2 when transmitting on frequencies between 120.45 and 121.1. It doesn’t happen every time, but I’ve observed it (and recorded it) on 5 or 6 separate occasions. My service center replaced the antenna associated with COM 1. And Russ, Diamond would not pay for the upgrade to the new style antenna under warranty. I can’t remember the exact quote, but I believe it was in the range of 5-7k to upgrade to new antenna so I elected to replace with the same style as came with the airplane. Long story short, replacing the antenna did not fix my GPS 1 and GPS 2 failures. Now Diamond has suggested we try replacing a GIA??? (can’t remember the specific number). So my 100 hour oil change and radar install has turned into a 3 week ordeal trying to chase down this GPS problem that we originally thought would be solved by a quick antenna swap out… Frustrating.

[Boatguy]

And Russ, Diamond would not pay for the upgrade to the new style antenna under warranty. I can’t remember the exact quote, but I believe it was in the range of 5-7k to upgrade to new antenna so I elected to replace with the same style as came with the airplane.

I'm not surprised since it is an Optional SB. But if you're under warranty they won't have that latitude for the parts and labor replacing a GIA64. What looked odd in the video was that the GIA does not lose the GPS satellites, it just blanks the display. As soon as the PTT was released, the display was back and all the satellites were there.

For reference by others, here is the antenna OSB.

[janders]

Any advice what I should ask for since I'm still under a 5 year tip-to-tail warranty which you can see here:

viewtopic.php?p=85471#p85471

[mfdutra]

Any advice what I should ask for since I'm still under a 5 year tip-to-tail warranty which you can see here:

Since you can reproduce the problem, make a service center fix it until you can't repro any longer. They will probably be able to repro this on the ground, which makes troubleshooting easier.

It may even be a bad antenna connector.

I was losing both GPS sporadically on my new DA62. Diamond replaced the GPS1 antenna and the problem was solved.