What happens if I fly 400' over a canyon?

[FilmIdol]

I'm too chicken to try this. Where I live, there are a lot of canyons and hills. If my setup limits AGL height to 400', what happens if I put the bird up to 400' above me at my location, then fly it over a 800' deep canyon? Will it maintain altitude, or drop to 400' AGL, which might be 600' below me, and possibly under a treeline in front of me where I would lose signal? Or will it maintain altitude?

 

[Subtle Shots]

It will maintain the 400' altitude reading no matter what canyons or valleys you fly over. If you manually descend down with the left stick and watch the altitude readout, you can actually go below zero....it will read a negative altitude number. I like to fly from high ground often and noticed this when swooping down low. Not a good idea if using return to home because if its to low it may not climb up high enough to get back to you without hitting the side of the hill when returning to home. I can test this out next time I fly if anyone is interested

 

[FilmIdol]

I would be interested in your tests. The reason I ask is I brought back my Typhoon from a trip down a shallow valley, probably 70' deep and a couple hundred feet wide. The battery was low, and the controller kept vibrating more and more insistently. When it does that, of course, it reduces the altitude to around 170', as I recall. What happened is I couldn't get the UAV to come back up to me, and I had no way to get to it. It "could" have been I was in Smart mode, but don't remember, so it is possible the UAV just wouldn't come closer to me, but it was quite a ways away when it did this. Perhaps the altitude for the low power safety is different than the 400' electronic fence. The end of the story is I was able to coax it to me and was able to reach out far enough to grab it as the motors died. It was a very close call.