A method and system is provided for determining the compatibility of an approach, to a landing runway, with an angular guidance mode, the approach being compatible with a linear guidance mode, the angular guidance being characterized by a lateral angle of precision, the linear guidance being characterized by a lateral divergence of precision. The method is implemented on a flight management system deployed aboard an aircraft and comprising a first step of determining a first distance representative of a maximum distance of use of the angular guidance, on the basis of the lateral angle of precision and of the lateral divergence of precision.