An attitude integrity and display system, the system comprising: a primary inertial reference unit (110, 120) configured to generate a primary attitude solution calculated at least in part as a function of inertial data from a first navigation-grade inertial sensor; a primary aircraft display system coupled to the primary inertial reference unit (110, 120), wherein the primary aircraft display system is configured to displays the primary attitude solution; a hybrid reference unit configured to generate a secondary attitude solution calculated at least in part as a function of inertial data from a second navigation-grade inertial sensor; a standby aircraft display system coupled to the hybrid reference unit, wherein the standby aircraft display system is configured to displays the secondary attitude solution; an attitude integrity system configured to generate an attitude integrity solution calculated by one or more measurements provided by a non-navigation grade attitude solution data source, wherein the attitude solution data source is configured to provides data independent from the first navigation-grade inertial sensor and the second navigation-grade inertial sensor, wherein the attitude integrity solution is not displayed on either the primary aircraft display system or the standby aircraft display system; an attitude monitor coupled to the attitude integrity system, wherein the attitude monitor includes a monitoring mode in which the attitude monitor is configured to compare the primary attitude solution against the secondary attitude solution; wherein the attitude monitor is configured to, when the primary attitude solution deviates from the secondary attitude solution by more than a predetermine threshold, identify either the primary attitude solution or the secondary attitude solution as a failed solution based on a determination of which of the primary attitude solution or the secondary attitude solution has a greatest deviation from the attitude integrity solution; and wherein the attitude monitor is configured to generate a warning on one or both of the primary or standby aircraft display system (160, 170) identifying the failed solution. a primary inertial reference unit (110, 120) configured to generate a primary attitude solution calculated at least in part as a function of inertial data from a first navigation-grade inertial sensor; a primary aircraft display system coupled to the primary inertial reference unit (110, 120), wherein the primary aircraft display system is configured to displays the primary attitude solution; a hybrid reference unit configured to generate a secondary attitude solution calculated at least in part as a function of inertial data from a second navigation-grade inertial sensor; a standby aircraft display system coupled to the hybrid reference unit, wherein the standby aircraft display system is configured to displays the secondary attitude solution; an attitude integrity system configured to generate an attitude integrity solution calculated by one or more measurements provided by a non-navigation grade attitude solution data source, wherein the attitude solution data source is configured to provides data independent from the first navigation-grade inertial sensor and the second navigation-grade inertial sensor, wherein the attitude integrity solution is not displayed on either the primary aircraft display system or the standby aircraft display system; an attitude monitor coupled to the attitude integrity system, wherein the attitude monitor includes a monitoring mode in which the attitude monitor is configured to compare the primary attitude solution against the secondary attitude solution; wherein the attitude monitor is configured to, when the primary attitude solution deviates from the secondary attitude solution by more than a predetermine threshold, identify either the primary attitude solution or the secondary attitude solution as a failed solution based on a determination of which of the primary attitude solution or the secondary attitude solution has a greatest deviation from the attitude integrity solution; and wherein the attitude monitor is configured to generate a warning on one or both of the primary or standby aircraft display system (160, 170) identifying the failed solution.