I found my answer in the manual, it is C and when control link lost it, uses GPS to continue through the plan. If GPS is lost it will sit at the spot until it reconnects to GPS. If GPS is lost (most likely from an illegal jammer) when flying over someones land, the drone will hover stationary at one spot until battery drains then WILL LAND ON THEIR LAND. 
This is the same for bb1, bb2 and disco.
So someone can just wait until you are above tall trees, switch a GPS jammer on and puts your drone right on top of a tree until battery runs out, then you will never see it again or will be an absolute nightmare to get it back. For that to happen you have to lose control of GPS AND wifi link. I think FFpro does show you number of satellites on the APP if that does ever happen, then determine that a jam is happening, but only of course if you still have link.
