Method for monitoring an aircraft by vibration acquisitions in flight, in the course of which: • during a stage prior to flights: - a plurality of types of vibration acquisition (acq k) is established, each specifying at least one acquisition condition determining when a vibration acquisition should be carried out and at least one acquisition characteristic determining how to carry out said vibration acquisition, an acquisition characteristic including at least one vibration measurement device, each acquisition condition being a flight phase, - a flight spectrum is initiated associating each flight phase (φi) with a duration of use of said flight phase from a given date, • in flight: - a) flight parameters measured by flight parameter sensors are read, - b) a current flight phase is determined according to the measured flight parameters, - c) the flight spectrum is updated by modifying the duration of use of said current flight phase, - d) at least one type of vibration acquisition specifying a plurality of acquisition conditions, an acquisition condition chosen from the type of vibration acquisition being the condition relating to the flight phase of this type of vibration acquisition having the longest duration of use, a vibration acquisition is carried out according to a particular type of vibration acquisition when the chosen acquisition condition of said particular type of vibration acquisition is equal to said current flight phase. • during a stage prior to flights: - a plurality of types of vibration acquisition (acq k) is established, each specifying at least one acquisition condition determining when a vibration acquisition should be carried out and at least one acquisition characteristic determining how to carry out said vibration acquisition, an acquisition characteristic including at least one vibration measurement device, each acquisition condition being a flight phase, - a flight spectrum is initiated associating each flight phase (φi) with a duration of use of said flight phase from a given date, - a plurality of types of vibration acquisition (acq k) is established, each specifying at least one acquisition condition determining when a vibration acquisition should be carried out and at least one acquisition characteristic determining how to carry out said vibration acquisition, an acquisition characteristic including at least one vibration measurement device, each acquisition condition being a flight phase, - a flight spectrum is initiated associating each flight phase (φi) with a duration of use of said flight phase from a given date, • in flight: - a) flight parameters measured by flight parameter sensors are read, - b) a current flight phase is determined according to the measured flight parameters, - c) the flight spectrum is updated by modifying the duration of use of said current flight phase, - d) at least one type of vibration acquisition specifying a plurality of acquisition conditions, an acquisition condition chosen from the type of vibration acquisition being the condition relating to the flight phase of this type of vibration acquisition having the longest duration of use, a vibration acquisition is carried out according to a particular type of vibration acquisition when the chosen acquisition condition of said particular type of vibration acquisition is equal to said current flight phase. - a) flight parameters measured by flight parameter sensors are read, - b) a current flight phase is determined according to the measured flight parameters, - c) the flight spectrum is updated by modifying the duration of use of said current flight phase, - d) at least one type of vibration acquisition specifying a plurality of acquisition conditions, an acquisition condition chosen from the type of vibration acquisition being the condition relating to the flight phase of this type of vibration acquisition having the longest duration of use, a vibration acquisition is carried out according to a particular type of vibration acquisition when the chosen acquisition condition of said particular type of vibration acquisition is equal to said current flight phase.