In this paper, the output-feedback global tracking problem is solved for the well-known nonlinear benchmark RTAC system, in which one of the unmeasured states appears quadratically in the state equations. Our novel observer/controller backstepping design yields a nonlinear output-feedback controller that forces the translational displacement to globally asymptotically track an appropriate time-varying signal. The proposed solution is new even for the case of global output-feedback stabilization, namely when the reference signal is zero.