A method for synchronizing a system including a plurality of input modules, a computer and a plurality of output modules, each including a plurality of redundant processing chains, each processing chain including a specific local clock (30, 32, 34) pacing the respective processing chain, the method including: - for each processing chain of the input module, for each produced input signal, associating a local input date with the input signal via the input module having produced the signal, - sending each input signal from the input module to the computer, - for each processing chain of the computer, generating output signals intended for one or several output modules, an output signal being the result of the application of a first function specific to the output signal to at least one received input signal, - for each output cycle, calculating an expiry duration of the output signal by using a second function, the second function being deduced from the first function specific to the output signal and applied on the local input dates associated with each received input signal on which the first specific function has been applied, - sending each output signal from the computer to the respective output module, - for each expiry duration of the output signal, an operation to change the time base from the clock of the input module to the clock of the output module done by the output module, - estimating, via each output module, each offset between the local clock of the output module and the local clock of the input module, the estimating being done by synchronization between the output module and the input module, the output module sending to the input module a signal containing the sending date according to its local clock and said input module in turn sending a signal containing the reception date according to its local clock of the signal previously sent by the output module, the offset corresponding to the difference between the reception date by the input module of the signal sent by the output module and the sending date by the output module of the signal sent to the input module, compensated by the worst-case transmission duration of the signal sent by the output module, the operation to change the time base being a function of the estimated offset. - for each processing chain of the input module, for each produced input signal, associating a local input date with the input signal via the input module having produced the signal, - sending each input signal from the input module to the computer, - for each processing chain of the computer, generating output signals intended for one or several output modules, an output signal being the result of the application of a first function specific to the output signal to at least one received input signal, - for each output cycle, calculating an expiry duration of the output signal by using a second function, the second function being deduced from the first function specific to the output signal and applied on the local input dates associated with each received input signal on which the first specific function has been applied, - sending each output signal from the computer to the respective output module, - for each expiry duration of the output signal, an operation to change the time base from the clock of the input module to the clock of the output module done by the output module, - estimating, via each output module, each offset between the local clock of the output module and the local clock of the input module, the estimating being done by synchronization between the output module and the input module, the output module sending to the input module a signal containing the sending date according to its local clock and said input module in turn sending a signal containing the reception date according to its local clock of the signal previously sent by the output module, the offset corresponding to the difference between the reception date by the input module of the signal sent by the output module and the sending date by the output module of the signal sent to the input module, compensated by the worst-case transmission duration of the signal sent by the output module, the operation to change the time base being a function of the estimated offset.