Lost GPS Integrity

[Bob]

Yesterday I lost GPS location to both my panel mounted 480 Garmin and also my Ipad while passing thru 8000. Leveled off at 14500 and ten minutes later regained connectivity on both units. I asked Center if they had any other reports and said no. While descending thru 12000, into Chicago, both units lost location again until 3 min after flying level at 3000. Not very nice in busy airspace! I am a little surprised that both independent units lost location. Only 2 things come to mind as "new" to this flight. I have a new cover on order and an waiting on the 30 day production time so I was forced to leave the plane uncovered last week while we had heavy rain. Also this was my first flight for the Halo headset. I did very little diagnosing in the air since I first wanted to know where I was at all times, thanks to VOR still in the panel! I did shut down the Ipad and reboot but showed no change. Any thoughts on possible causes?

 

[wrench]

Any Narco VHF Navigation radios installed?

[Bob]

Quote: flyingwrench

Any Narco VHF Navigation radios installed?

[wrench]

I only mentioned Narco Nav's because I have had them mask the GPS signal from a Garmin 196 and a Sykmap II at the very same time in a certain "NAV" frequency range. I found it by using a hand held Sporty's NAV/COM and scanning each NAV frequency with the handheld radio being held next to the Garmin 196. A local avionics shop confirmed it when I got back home and I soon after got rid of the old Narco Nav's or left them turned off when using the GPS.

Not much help for you I know but apparently GPS signal masking can occur from unexpected sources.

[Magnum]

Garmin had problems with a batch of defective GPS antennas. When the antenna failed it "jammed" other antennas nearby. There were several dual GNS430 installations where both units lost reception at the same time. They usually regained reception after a short time (couple of minutes).

[Piloto]

The problem may be related to the autopilot pitch servo, since it only happened when you were not level. In level flight altitude is maintained by the trim servo. While in descent or climb attitude is maintained by the pitch servo. Next time pull the A/P CB to see if that has any effect.

 

José

[Lionudakis]

Do the 2 units have seperate antenna's? Mounted near each other? The signal loss was following any radio call's ? Or series of calls ? You've flown the same equip in the same airspace on same freq before? 

 

[Lionudakis]

weather?

..and do you have any static wicks, broken or damaged ones. Airliners are very effected by staticwicks missing or damaged                       .............................and your near them kind of speeds and altitudes :-)

[jelswick]

I have no idea whether it would have anything to do with it, but I'm remembering reading info on AOPA's site that the new Lightsquared or other 4G coverage could an issue for GPS navigation.  Is that concern now obsolete or resolved?  Just seems odd both independent units unless sharing the same antenna would lose position at the same time. 

[Lionudakis]

It does raise eyebrows at the idea of redundancy, if these new signals are going to kill everything gps based at once. Next we'll need to back up the gps with rnav or IRS system if these other signals are allowed to interfere. A 180 I restored has been having issues with his dropping off at once, but it's been doing it for 2 years, before theses signals were introduce, all components were swapped out, so next is some sort of static charges as it usually happens at the best times (real ifr) 

[Lionudakis]

jelswick, your paint job inspired me to repaint :-) I like..

 

[jelswick]

Thank you!  She was pretty before in her original paint, but was losing too much of it and I told my wife it would be cheaper to repaint than to address any resulting corrosion issues she might get without her protective paint!    I also had to edit that post because I had refered to "Lightspeed" which is actually the maker of our wonderful Zulu's; I think Lightsquared was the company AOPA was referencing with the 4G signal issues; I didn't keep up with it enough to know if it's been resolved yet.  Hope you and all had a wonderful Thanksgiving! 

[Bob]

Quote: jelswick

Thank you!  She was pretty before in her original paint, but was losing too much of it and I told my wife it would be cheaper to repaint than to address any resulting corrosion issues she might get without her protective paint!   

[Bob]

Thanks everyone for all the ideas!  If we don't find the problem next week at the Annual, then I will see the avionics guy the following week. 

[RJBrown]

Quote: Lionudakis

It does raise eyebrows at the idea of redundancy, if these new signals are going to kill everything gps based at once. Next we'll need to back up the gps with rnav or IRS system if these other signals are allowed to interfere. A 180 I restored has been having issues with his dropping off at once, but it's been doing it for 2 years, before theses signals were introduce, all components were swapped out, so next is some sort of static charges as it usually happens at the best times (real ifr) 

[jetdriven]

There are always VORs for a backup