An integrity monitoring method carried out by a navigation system using heterogeneous measurements from a plurality of different type navigation related measurement information sources, the method comprising: defining integrity monitoring classes specifying quantities of a navigation information to be protected; receiving measurements from the plurality of different type navigation related measurement information sources ; characterized in that the method further comprises: categorizing the measurements by an information domain , an aiding class and an aiding section , wherein the information domain is a category of at least one of estimated states that represent a same physical quantity and measurements that represent a same physical quantity, wherein the aiding class is a category that uses a same physical method to acquire measurements, wherein the aiding section is a category of measurements from the same navigation related measurement information source; organizing the categorized measurements into a plurality of measurement clusters based at least in part on measurement fault modes to be detected, measurement fault modes to be excluded, available computer resources and required performance; and applying an integrity monitoring algorithm based on a solution separation methodology to the measurement clusters to determine an integrity solution for all defined integrity monitoring classes. defining integrity monitoring classes specifying quantities of a navigation information to be protected; receiving measurements from the plurality of different type navigation related measurement information sources ; characterized in that the method further comprises: categorizing the measurements by an information domain , an aiding class and an aiding section , wherein the information domain is a category of at least one of estimated states that represent a same physical quantity and measurements that represent a same physical quantity, wherein the aiding class is a category that uses a same physical method to acquire measurements, wherein the aiding section is a category of measurements from the same navigation related measurement information source; organizing the categorized measurements into a plurality of measurement clusters based at least in part on measurement fault modes to be detected, measurement fault modes to be excluded, available computer resources and required performance; and applying an integrity monitoring algorithm based on a solution separation methodology to the measurement clusters to determine an integrity solution for all defined integrity monitoring classes. categorizing the measurements by an information domain , an aiding class and an aiding section , wherein the information domain is a category of at least one of estimated states that represent a same physical quantity and measurements that represent a same physical quantity, wherein the aiding class is a category that uses a same physical method to acquire measurements, wherein the aiding section is a category of measurements from the same navigation related measurement information source; organizing the categorized measurements into a plurality of measurement clusters based at least in part on measurement fault modes to be detected, measurement fault modes to be excluded, available computer resources and required performance; and applying an integrity monitoring algorithm based on a solution separation methodology to the measurement clusters to determine an integrity solution for all defined integrity monitoring classes. <EOS>