A method for monitoring the validity of at least one parameter which is calculated by an anemometric unit of an aircraft, said method allowing at least one of the following parameters calculated by the anemometric unit to be monitored: the total pressure, the static pressure, and the total temperature, said method wherein: a) a number n of first data are taken into account, each dependent on said parameter which is being monitored, n being an integer greater than or equal to 1; b) a plurality of p second data are taken into account, p being an integer greater than or equal to 2, each of said p second data being of the same type as one of said n first data and dependent on at least one value obtained from at least one data source (Si) which is external to said anemometric unit, the various data sources (Si) furthermore being separate from one another; c) for each of said p second data, a difference is calculated between this second datum and a first datum of the same type, two data being of the same type if they relate to the same quantity and are expressed in the same units; d) the absolute value of each of the differences calculated in this way is compared with a predetermined threshold value, in each case dependent on the data type corresponding to said difference; and e) the following are deduced from said comparisons:. that said parameter is invalid if the absolute values of at least two of said various differences are greater than the corresponding predetermined threshold values; and. that said parameter is valid otherwise. the total pressure, the static pressure, and the total temperature, said method wherein: a) a number n of first data are taken into account, each dependent on said parameter which is being monitored, n being an integer greater than or equal to 1; b) a plurality of p second data are taken into account, p being an integer greater than or equal to 2, each of said p second data being of the same type as one of said n first data and dependent on at least one value obtained from at least one data source (Si) which is external to said anemometric unit, the various data sources (Si) furthermore being separate from one another; c) for each of said p second data, a difference is calculated between this second datum and a first datum of the same type, two data being of the same type if they relate to the same quantity and are expressed in the same units; d) the absolute value of each of the differences calculated in this way is compared with a predetermined threshold value, in each case dependent on the data type corresponding to said difference; and e) the following are deduced from said comparisons:. that said parameter is invalid if the absolute values of at least two of said various differences are greater than the corresponding predetermined threshold values; and. that said parameter is valid otherwise. a) a number n of first data are taken into account, each dependent on said parameter which is being monitored, n being an integer greater than or equal to 1; b) a plurality of p second data are taken into account, p being an integer greater than or equal to 2, each of said p second data being of the same type as one of said n first data and dependent on at least one value obtained from at least one data source (Si) which is external to said anemometric unit, the various data sources (Si) furthermore being separate from one another; c) for each of said p second data, a difference is calculated between this second datum and a first datum of the same type, two data being of the same type if they relate to the same quantity and are expressed in the same units; d) the absolute value of each of the differences calculated in this way is compared with a predetermined threshold value, in each case dependent on the data type corresponding to said difference; and e) the following are deduced from said comparisons:. that said parameter is invalid if the absolute values of at least two of said various differences are greater than the corresponding predetermined threshold values; and. that said parameter is valid otherwise.. that said parameter is invalid if the absolute values of at least two of said various differences are greater than the corresponding predetermined threshold values; and. that said parameter is valid otherwise.