In this paper, a sensorless output feedback controller is designed in order to drive the Induction Motor IM without the use of flux and speed sensors. Firstly, an observer that uses only the measured stator currents is synthesized to estimate the mechanical variables (speed and load torque) and the magnetic variables (fluxes) by structurally taking into account the unobservability phenomena of the Sensorless IM (SIM) and the parametric uncertainties. Secondly, a current-based field oriented sliding mode control, that uses the flux and the speed estimates given by the former observer is developed so as to steer the estimated speed and flux magnitude to the desired references. Since the observer design is independent of the control and depends on theIM parametric uncertainties, a separation principle is introduced to guarantee the practical stability of the whole closed-loop system "observer -controller" ("O-C") according to observability and unobservability time variation. A significant benchmark taking into account the unobservability phenomena of the \textit{SIM} is presented to show the performances of the whole control scheme against experimental set-up.