A measurement unit for measuring a first static pressure of the ambient air in a first measurement zone of the aircraft, a measurement unit for measuring a second pressure of the ambient air, at least one static pressure probe, in a second measurement zone of the aircraft, the second pressure having a value lower than the first static pressure, a computation unit for estimating a Mach number using these two measured pressures and a data transmission unit configured to transmit the estimated Mach number to a user system.