Method for determining a probability of occurrence of a malfunction (Mf) creating a performance defect in an aircraft with a view to carrying out a maintenance action accordingly, the method being characterized in that it is executed by a computing system comprising electronic circuitry that implements the following steps: - acquiring a set (DtS) of input data (Dt) each relating to the occurrence of said malfunction (Mf) in an aircraft, each input datum (Dt) comprising a timestamped notification of the malfunction (Mf) and a timestamped record of measurements (Ts) from sensors of the aircraft; - grouping the input data (Dt) into groups of malfunctions (Mf) having the same root cause; - delimiting a causal time window for the malfunction (Mf), an upper bound of the causal time window being the timestamped notification of the malfunction (Mf), and, for each input datum (Dt), retaining only a sample (Sp) containing the measurements (Ts) contained within the causal time window; - weighting each measurement (Ts) of the same sample (Sp), the sum of the weights of the same sample (Sp) being equal to 1; - filtering the measurements of each sample so as to retain only measurements of interest with respect to the malfunction; - comparing the measurements of interest (Im) of each sample (Sp) with reference measurements (Rm), and for each measurement of interest (Im) of a sample that is greater than the corresponding reference measurement (Rm), assigning a first Boolean value (Tr) to said measurement of interest (Im), and for each measurement of interest (Im) of a sample that is less than the corresponding reference measurement (Rm), assigning a second Boolean value (Fls) to said measurement of interest different from the first Boolean value (Tr), so as to obtain a series of Boolean values (Bs); - splitting each group into a plurality of subgroups, each subgroup corresponding to a variation of one or more Boolean values of the series of Boolean values (Bs), such that, for each group, there are 2 n subgroups, where n is the number of Boolean values, and dividing each sample of the same group into a subgroup corresponding to the Boolean values of each sample; - calculating the sum of the weights of the measurements of each subgroup; - using the sum of the weights of each subgroup to determine a probability of occurrence of the malfunction for each subgroup. - carrying out a maintenance action on an aircraft according to the determined probability of occurrence of the malfunction. - acquiring a set (DtS) of input data (Dt) each relating to the occurrence of said malfunction (Mf) in an aircraft, each input datum (Dt) comprising a timestamped notification of the malfunction (Mf) and a timestamped record of measurements (Ts) from sensors of the aircraft; - grouping the input data (Dt) into groups of malfunctions (Mf) having the same root cause; - delimiting a causal time window for the malfunction (Mf), an upper bound of the causal time window being the timestamped notification of the malfunction (Mf), and, for each input datum (Dt), retaining only a sample (Sp) containing the measurements (Ts) contained within the causal time window; - weighting each measurement (Ts) of the same sample (Sp), the sum of the weights of the same sample (Sp) being equal to 1; - filtering the measurements of each sample so as to retain only measurements of interest with respect to the malfunction; - comparing the measurements of interest (Im) of each sample (Sp) with reference measurements (Rm), and for each measurement of interest (Im) of a sample that is greater than the corresponding reference measurement (Rm), assigning a first Boolean value (Tr) to said measurement of interest (Im), and for each measurement of interest (Im) of a sample that is less than the corresponding reference measurement (Rm), assigning a second Boolean value (Fls) to said measurement of interest different from the first Boolean value (Tr), so as to obtain a series of Boolean values (Bs); - splitting each group into a plurality of subgroups, each subgroup corresponding to a variation of one or more Boolean values of the series of Boolean values (Bs), such that, for each group, there are 2 n subgroups, where n is the number of Boolean values, and dividing each sample of the same group into a subgroup corresponding to the Boolean values of each sample; - calculating the sum of the weights of the measurements of each subgroup; - using the sum of the weights of each subgroup to determine a probability of occurrence of the malfunction for each subgroup. - carrying out a maintenance action on an aircraft according to the determined probability of occurrence of the malfunction.