We received a message from Bruce this morning that his Spot Trace Tracker is interfering with the GPS signal on his Garmin glass panel displays particularly the GTN750 & G500.
He describes that every 5 minutes when his Spot Trace transmits a GPS position it causes the GTN750 to lose its GPS position input to the aircraft for 10-20 seconds. This fault would seem like a benign nuisance in cruise or during VFR flight but could prove to be potentially catastrophic during an IFR RNAV approach.
Bruce has contacted Garmin and Spot to seek a resolution even though the SPOT manual states that the device will not cause interference with other electronic components.
He states that when the Spot Trace is on the dash it interferes with ALL other GPS inputs every 5 minutes and if he relocates the tracker to the aft window of the plane that it interferes with 1/3 components.
According to a local avionics dealer, the Spot device is on a very similar frequency as Garmin. When it powers up or pulses (as defined by the user, in this case every 5 mins) the Garmin GTN 750 dumps ALL satellites and then quickly reacquires. Because the G500 gets its feed from the GTN 750 it also loses its GPS position. Now the GTN750 reacquires within a second or two but the G500 takes a bit longer and the synthetic vision returns about 10secs after the cycle begins.
It is unknown if this issue is isolated to only his Spot Trace or if others may cause similar issues. It is also unknown if Spot Gen2/3 units will cause similar problems.
The video in the link below demonstrates this phenomenon through 2 complete cycles. Please use caution if you are operating IFR with a newer Garmin installation and a Spot Tracker.