Most common piloting modes for a rotorcraft UAV: >[!abstract] GPS mode >The UAV uses the GPS satellite signal to self-correct and stabilize its position in both the horizontal (pitch, roll) and vertical (throttle) planes to hover in place in the absence of control stick inputs. >[!abstract] OPTI mode >Uses both GPS and sensors (infrared, optical, etc.) to hover in place. >[!abstract] ATTI mode >The UAV does not self-correct and only hovers in place if left undisturbed (in accordance with [[Newton's laws of motion|Newton’s first law of motion]]). As a result: >- It will drift with both the wind and the gyroscopic effect of motion in the yaw axis. >- It may slowly bleed altitude when applying deliberate inputs to one stick’s axis results in unwanted inputs to the other axis (e.g., commanding yaw and involuntarily commanding throttle using the left control stick in [[Remote controller modes|Mode 2]]). >In my experience, I could maneuver in ATTI mode for about 20–30 seconds before having to correct altitude using the throttle, though that was always unidirectional (adding altitude after the UAV had descended slightly over time).