A navigation filter for a navigation system using terrain correlation delivering an estimation of the kinematic state of a carrier craft using a plurality of data includes the measurements returned by at least one terrain sensor, the model associated with the terrain sensor, the data from an onboard map, an error model for the onboard map, the measurements returned by an inertial guidance system, and a model of the inertial guidance system. The navigation filter also includes a first filter referred to as convergence filter, for example of the Kalman filter type, and a second filter referred to as tracking filter, for example of the particle filter type.