Abstract: A method and system for controlling clearance between the tips of blades of a turbine rotor in a gas turbine airplane engine and a turbine ring of a casing surrounding the blades. A valve is controlled to act on a flow rate and/or a temperature of air directed against the casing. The valve is of the on/off type for switching between an open state and a closed state in a determined reaction time, the valve control module including a corrector for determining a first binary control signal that can take a first value corresponding to an open state and a second value corresponding to a closed state of the valve. The corrector includes a time-delay module for determining a binary control signal, with the duration between two successive changes of state in the control signal being not less than the reaction time of the valve.