Analysis of aided inertial navigation systems performance on international routes

The performance of hybrid navigation systems for commercial transoceanic flights is evaluated by means of a digital computer simulation. Error models are developed for aided-inertial navigation systems with external measurements from Doppler radar, Omega and satellite-ranging. Key features of the simulation program AIRNAV (Aided-Inertial Reference NAVigation) are described. Covariance matrix error analysis is used to obtain the navigation error histories, with recursive navigation techniques to incorporate the measurements. A 34th-order error state vector is defined, which requires the numerical integration of up to 585 first-order differential equations to propagate the covariance matrix. Example computer results are presented for a typical North Atlantic flight.