Method for assisting with the navigation of a vehicle

A method of assisting navigation of a vehicle equipped with a navigation device, the method comprising the following steps:

• acquiring a priori values of kinematic variables of the navigation device;
• determining respective current values of the kinematic variables of the navigation device and a current uncertainty matrix representative of an uncertainty on the respective current values of the kinematic variables, from:
• respective preceding values of the kinematic variables,
• a preceding uncertainty matrix representative of an uncertainty on the respective preceding values of the kinematic variables, and
• a model of a terrestrial gravity experienced by the navigation device, wherein an intensity of a gravity modelled by the model increases with an altitude of the navigation device;
• determining a correction from:
• the respective current values of the kinematic variables and
• the current uncertainty matrix, and
• a measurement;
• and
• updating the respective current values of the kinematic variables and of the current uncertainty matrix from the correction and from the current uncertainty matrix.