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.