testing this controller - shark x6 controller. if you see the quad in one place for a little bit is gps. moving around at the same height is gps altitude hold. flying around is balance mode. balance, altitude, gps, headless and return to home modes work fine. rth works but i turn it off when it gets close to home. gps works amazing when there is enough satellites. this is my first controller with gps that i struggled to configure. it's very functional and cost under $90 from hk.