In this session we will add the Altitude Hold flight mode and repeat the flight patterns above. Altitude Hold uses the barometric sensor to maintain altitude. Utilizing this mode may require some tuning of the Altitude Hold settings. The multirotor may slowly decrease in altitude during flight, this is common as the barometric sensor may sense an increase of air pressure from forward movement, thus retards the motor speed to return to its original pressure value. The faster the flight speed the more the altitude decrease may be. You can compensate for this by decreasing the flight speed or increasing the throttle stick during flight and returning back to ~50% when hovering. Compensating for uncommanded altitude changes can be easily by adjusting throttle position while in Altitude Hold. Holding altitude becomes more critical in Waypoint flights as the AutoPilot (AP) function disregards all control stick movements (except for yaw) during AP flight. Adding a optional LIDAR sensor should help maintain more accurate altitude hold during varied flight conditions. More information on using and adjusting the Altitude Hold can be found here: Alt Hold