1. A method for providing integrity for a hybrid navigation system using a Kalman filter, the method comprising: receiving signals from a plurality of global navigation satellite system (GNSS) satellites at a vehicle; obtaining inertial measurements from one or more inertial sensors on the vehicle; determining a main navigation solution for one or more of roll, pitch, platform heading, or true heading for the vehicle using data from the signals from a plurality of GNSS satellites and the inertial measurements; using solution separation to determine a plurality of sub-solutions for the main navigation solution; determining a separation between the main navigation solution and each of the sub-solutions; determining a discriminator for each of the separations; if a discriminator is greater than the threshold determining which of the GNSS satellites is at fault and excluding the GNSS satellite at fault; determining a separation variance between the main navigation solution and each of the sub-solutions; determining a threshold for detection of a satellite failure based on the separation variances and an allowable false alert rate; and determining a protection limit that bounds error in the main navigation solution based on the threshold and an allowable missed detection probability.