We consider adaptive output feedback neuro-control of uncertain nonlinear systems, and in particular its application to high-bandwidth flight control of unmanned rotorcraft. Given a smooth reference trajectory, the problem is to design a controller that would force the system measurement to track it asymptotically or with bounded errors. The classical approach necessitates building state observers. The state estimates are used both in the controller design and in the adaptation laws. However, finding a good observer for an uncertain nonlinear plant is not an obvious task. We argue that it should be sufficient to build an observer for the output tracking error only. The method is employed in the design of a high-bandwidth attitude command system for an unmanned helicopter.