iFly GPS Forum

I, too, had problems with false terrain warnings on my 720 after I mounted it on a knee board in my CH701 in portrait mode. Since adding an external antenna, (velcroed to the cowl) I've had no further problems. The unit locks on as soon as I push out of the hangar, and remains rock steady with 9-12 satellites received.

I too am getting false terrain warnings after switching to the 720 from the 700. Both were mounted in the identical place, suction-cupped above the dash on a Cessna. Each time it happened, difference between GPS altitude and ground was in excess of 2000 feet.

I had to use the external antenna with my last GPS (Airmap 1000) in both my planes (C-182 and Grumman Yankee) to provide reliable service. When I got the 700 I was glad to see it worked great in both planes without the external antenna (and associated wire running to the yoke). When I upgraded to the 720, I also started using the portrait mode exclusively, and have been getting the terrain warnings. Since I fly mostly day VFR, it would be a choice of adding the antenna or disabling the terrain feature. I would probably disable the terrain.
I might try making a couple flights in the Landscape mode to see if it makes a difference.