Inertial unit performing hybrid navigation by integrated loose coupling

The unit (1) has a global positioning receiver (2) receiving satellite signals from multiple satellites distributed in two disjoint subsets satellites (5a-5c) and calculating two navigation solutions e.g. global positioning system (GPS) PVT solution. A satellite fault detector (4) compares hybrid navigation solutions and detects inconsistency between the hybrid navigation solutions and failure of a satellite belonging to the subsets satellites. A hybridization module (3) stops hybridization application based on detection of a mismatch between the hybrid navigation solutions. An independent claim is also included for a method for hybridizing loose coupling operator measures inertial measurements.