In this paper, we address the problem of controlling a nonlinear system in the presence of parametric uncertainties. The adaptive controller proposed includes a a nominal controller which is based on gain-scheduling and an adaptive component where adjustable parameters are self-tuned in order to accommodate the system uncertainties. The resulting closed-loop system is shown to have globally bounded solutions when the command signals that need to be tracked vary sufficiently slowly. The reported stability results are validated using nonlinear flight simulation models of a high performance aircraft.