1. Method for determining protection limits at a future moment associated with navigation states of a carrier, including steps consisting of: estimating navigation states of the carrier at the present moment, producing a statistical model of estimation errors of navigation states of the carrier at the present moment in the form of a covariance matrix, extrapolating the statistical model of estimation errors to a future moment, calculating a protection limit at a future moment using the extrapolated statistical model, characterised in that extrapolation of the statistical estimation error model applies a constant positive transition matrix to a standard deviation vector constructed from the square roots of the elements of the diagonal of the covariance matrix to propagate standard deviations of navigation states produced at the present moment, to a future moment.