Method for navigating a vehicle having an inertial navigation system, comprising the step of calculating successive positions and headings of the vehicle from signals of the inertial navigation system, the method also comprising the steps of: - detecting at least one period of immobility in terms of both the heading and the position of the vehicle, - processing the signals provided by the inertial navigation system during said period of immobility in order to identify an error of the inertial navigation system, - taking into account the error identified in the calculation of the position and heading of the vehicle from the signals of the inertial navigation system; characterised in that the detection of immobility comprises detecting immobility in terms of heading, which comprises the phases of: - integrating signals from accelerometer sensors and angle sensors of the inertial navigation system, into a rotating reference frame according to a detectable orientation of the angle sensors, in order to obtain a raw heading signal for a predetermined period of time, - saving the raw heading signal for said predetermined period of time, - determining the parameters of a theoretical modelling signal of the raw heading signal depending on a predetermined error model in the absence of movement, - calculating a residual signal between the theoretical modelling signal and the raw heading signal, - calculating an Allan variance from the residual signal, - calculating a difference between the calculated Allan variance and a theoretical Allan variance while the heading is immobile, - confirming the immobility of the heading if the difference is less than a predetermined threshold; and in that the taking into account of the error comprises a step of determining a temporal evolution of the error based on an error model of the inertial navigation system and the step of integrating the error in time in order to determine the heading actually followed. - detecting at least one period of immobility in terms of both the heading and the position of the vehicle, - processing the signals provided by the inertial navigation system during said period of immobility in order to identify an error of the inertial navigation system, - taking into account the error identified in the calculation of the position and heading of the vehicle from the signals of the inertial navigation system; - integrating signals from accelerometer sensors and angle sensors of the inertial navigation system, into a rotating reference frame according to a detectable orientation of the angle sensors, in order to obtain a raw heading signal for a predetermined period of time, - saving the raw heading signal for said predetermined period of time, - determining the parameters of a theoretical modelling signal of the raw heading signal depending on a predetermined error model in the absence of movement, - calculating a residual signal between the theoretical modelling signal and the raw heading signal, - calculating an Allan variance from the residual signal, - calculating a difference between the calculated Allan variance and a theoretical Allan variance while the heading is immobile, - confirming the immobility of the heading if the difference is less than a predetermined threshold;