A method of assisting navigation of a vehicle fitted at least with a first positioning device and with a second positioning device, the method comprising the steps of: • at predetermined instants, causing first positions of the vehicle to be determined by the first positioning device and second positions of the vehicle to be determined by the second positioning device, and calculating the value of a first discrepancy between each first position and the second position at the same instant; and • comparing the value of the first discrepancy with a first threshold, and issuing a first warning when the value of the first discrepancy is greater than the first threshold; the method further comprising the steps of: • defining on a screen of the vehicle both a reference point corresponding to a current position of the vehicle determined from the most recent first position and also a surrounding zone around the reference point and constituting a two-dimensional representation, at a predetermined scale and in a predetermined reference frame, of a portion of the space surrounding the vehicle; and •. symbolizing the first discrepancies on the screen by allocating a first symbol to each first discrepancy and by positioning each first symbol on the screen, relative to the reference point, while taking account both of the value of the first discrepancy and also of the path travelled by the vehicle since calculating the value of the first discrepancy, the first symbols being provided with respective chronological indicators. • at predetermined instants, causing first positions of the vehicle to be determined by the first positioning device and second positions of the vehicle to be determined by the second positioning device, and calculating the value of a first discrepancy between each first position and the second position at the same instant; and • comparing the value of the first discrepancy with a first threshold, and issuing a first warning when the value of the first discrepancy is greater than the first threshold; the method further comprising the steps of: • defining on a screen of the vehicle both a reference point corresponding to a current position of the vehicle determined from the most recent first position and also a surrounding zone around the reference point and constituting a two-dimensional representation, at a predetermined scale and in a predetermined reference frame, of a portion of the space surrounding the vehicle; and •. symbolizing the first discrepancies on the screen by allocating a first symbol to each first discrepancy and by positioning each first symbol on the screen, relative to the reference point, while taking account both of the value of the first discrepancy and also of the path travelled by the vehicle since calculating the value of the first discrepancy, the first symbols being provided with respective chronological indicators. • defining on a screen of the vehicle both a reference point corresponding to a current position of the vehicle determined from the most recent first position and also a surrounding zone around the reference point and constituting a two-dimensional representation, at a predetermined scale and in a predetermined reference frame, of a portion of the space surrounding the vehicle; and •. symbolizing the first discrepancies on the screen by allocating a first symbol to each first discrepancy and by positioning each first symbol on the screen, relative to the reference point, while taking account both of the value of the first discrepancy and also of the path travelled by the vehicle since calculating the value of the first discrepancy, the first symbols being provided with respective chronological indicators.