GPS Jammming in the SE US

[N941WR]

In case you aren't aware of it, the US military (Navy?) is performing some tests off the coast of Georgia and the GPS signal will be unreliable.

Here is a link to AOPA's article on the issue.

Two questions:

1) My question is how will the Dynon SkyView, Garmin G3X, and the other integrated EFIS's react when they receive an unreliable GPS signal?

2) What will that do to our ADS-B reporting? Will the FAA ask us to turn off our ADS-B transmitters because we putting out erroneous location data?

[SPX]

Originally Posted by N941WR

In case you aren't aware of it, the US military (Navy?) is performing some tests off the coast of Georgia and the GPS signal will be unreliable.

Here is a link to AOPA's article on the issue.

Two questions:

1) My question is how will the Dynon SkyView, Garmin G3X, and the other integrated EFIS's react when they receive an unreliable GPS signal?

2) What will that do to our ADS-B reporting? Will the FAA ask us to turn off our ADS-B transmitters because we putting out erroneous location data?

In the case of these NOTAM's, "unreliable" usually means you won't get a signal at all.. So:

1) In some areas, you are likely to have no GPS position available, so anything that relies on GPS will be inop (position, ownship moving map, traffic altitudes relative to you, etc.)

2) You likely won't be putting out an erroneous location, but rather no location at all. So, ATC will see your radar return from your transponder only.

[FlyGuy65]

There was a similar NOTAM over the northwest US spring 2018. No indication of weak or bad GPS signal until the magenta line jumped a few miles. ATC notified, reports filed. This was on an aircraft with dual GPS/INS/FMC etc. I now consider any GPS signal received while actively NOTAMed like this as deliberately wrong unless ATC says otherwise.

[BillL]

I don't have an INS installed so, if signal is in error won't WAAS indication give an error since all satellites won't be affected equally?

If INOP then red X's and what does A/P do, revert to pitch/roll hold?

[sailvi767]

Originally Posted by FlyGuy65

There was a similar NOTAM over the northwest US spring 2018. No indication of weak or bad GPS signal until the magenta line jumped a few miles. ATC notified, reports filed. This was on an aircraft with dual GPS/INS/FMC etc. I now consider any GPS signal received while actively NOTAMed like this as deliberately wrong unless ATC says otherwise.

There is a strong possibility the GPS failed completely causing the aircraft to downgrade to INS causing the magenta line to jump to the INS position. This used to be a common occurrence on the 767 pre GPS when it jumped from INS to LNAV on coast in after a Atlantic crossing.