Patent ID: 7617023

Claim:
A process for monitoring the validity of at least one speed cue of an aircraft, which is determined on the basis of at least one value of static pressure and of at least one value of total pressure, wherein the following is carried out repetitively on a computer: considering said values of static and total pressure, simultaneously used to determine said speed cue; calculating a coefficient of lift Cz which is representative of the lift of the aircraft on the basis of said values of static and total pressure; calculating a first value of angle of incidence from the values of static and total pressure via the calculated coefficient of lift; determining a second value of angle of incidence; computing the difference between said first and second values of angle of incidence; comparing the absolute value of this difference with a predetermined threshold value; and from said comparison one deduces that: said speed cue is valid, if the absolute value of said difference is below said threshold value; and said speed cue is not valid, otherwise, wherein: calculating said coefficient of lift Cz with the aid of the following expressions: { Cz = nz . m . g 0.7 . PS . M 2 . S M = 5 ⁡ [ ( PT PS ) 2 / 7 - 1 ] in which: PS represents said static pressure value; PT represents said total pressure value; M represents the Mach number of the aircraft; S represents a reference area which depends on the geometry of the aircraft; nz represents the longitudinal load factor of the aircraft; m represents the mass of the aircraft; and g represents the acceleration due to gravity.