I have completed around 60 hours with sky demon on ipad1 with built in GPS. Never a problem.
However... Last night went for an evening flight and lost GPS lock at 5000ft
I also tried using my IPad on a commercial flight back from Nice. I have the track plotted beautifully up to 10,000ft, but then it disappears until the descent into Gatwick.
Anyone know why the lock gets worse with altitude?