Method of detecting attitude faults based on magnetometer measurements

A method of monitoring attitude faults in an avionics system, the method comprising:

• obtaining an attitude solution;
• obtaining a geographic position of the avionics system;
• obtaining a measured magnetic field estimate in a frame of the avionics system;
• computing an Earth Magnetic Field Model (EMFM) estimate in a reference frame based, at least in part, on the geographic position of the avionics system;
• transforming at least one of the measured magnetic field estimate or the EMFM estimate based on the attitude solution such that the measured magnetic field estimate and the EMFM estimate are in a common shared frame;
• determining if a difference between the measured magnetic field estimate and the EMFM estimate in the common shared frame exceeds a predetermined threshold;
• if the difference exceeds the predetermined threshold, outputting an alert indicating that the attitude solution is in error.

A program product comprising a processor-readable medium on which program instructions are embodied, wherein the program instructions are configured, when executed by at least one programmable processor, to cause the at least one programmable processor to:

• receive a measured magnetic field estimate in a frame of an avionics system;
• compute an Earth Magnetic Field Model (EMFM) estimate in a reference frame based, at least in part, on a geographic position of the avionics system;
• transform at least one of the received measured magnetic field estimate or the EMFM estimate based on an attitude solution received from an attitude source such that the measured magnetic field estimate and the EMFM estimate are in a common shared frame;
• determine if a difference between the measured magnetic field estimate and the EMFM estimate in the common shared frame exceeds a predetermined threshold;
• and
• output an alert indicating that the attitude solution is in error if the difference exceeds the predetermined threshold.