A method for assisting in the navigation of an aircraft comprises steps of calculating and displaying a linear deviation on a first linear section and an angular deviation on a second angular section. The method comprises a step of calculation of an anticipated deviation of the aircraft, expressed linearly or angularly, projected to a time DT, characteristic of a reaction time of the aircraft, and of a statistical error distribution associated with this anticipated deviation; and a step of calculation of a probability of exceeding a predetermined target deviation, by means of the anticipated deviation and of the statistical error distribution. The method also comprises a crew alert when the probability is above a predetermined threshold.