An unmanned aerial vehicle (UAV) including a winch system, wherein the winch system includes a single winch line, wherein a payload is suspended from a first end of the winch line, and the winch system is controllable to vary the rate of ascent of the payload to the UAV, and a control system including a processor and program instructions stored in a non-transitory computer readable medium and executable by the processor to control the winch, the control system configured to (a) receive data regarding oscillations of the payload, and (b) operate the winch system to vary a retraction rate of the winch line to damp oscillations of the payload during ascent of the payload to the UAV.