1. Flight Altitude Hold and Adjust
very common in autopilot, basically an altitude tracking loop with an flight path angle/or pitch attitude inner loop
2. Direction hold and adjust
very common in autopilot, basically an heading tracking loop with an bank angle inner loop with an roll rate inner loop.
3. Loiter mode, plane flying circle around fixed coordinate on the ground
4. Follow mode (follow object on ground --- not essential, good to have)
5. Way point mode, preset way point linked to GPS coordinates (can over ride from ground control)
3,4,5 are basically the same. Auto pilot uses the same logic for this one, you just have to do is to provide different references.
