Application example: GPSIRS positioning on board commercial aircraft
Integration of the GPS with integrated navigation systems

Commercial aircraft have been using inertial navigation systems for en-route positioning since the 1970s, and GPS since the mid-1990s. In fact, they are equipped with ADIRUs (Air Data Inertial Reference Units): the inertial solution provides positioning in the horizontal plane only, while vertical positioning is provided by a baro-altimeter, which is also used to recalibrate inertial vertical acceleration and velocity within the platform.

There are three main types of baro-IRS/GPS hybridization on board commercial aircraft:

• Honeywell's first loose hybridization solution;

• two close-hybridization solutions: one from Honeywell, the other from Northrop Grumman.

These three solutions are therefore based on the assumption that the information provided by the GPS receiver is complete.

Since the integrity provided by the GPS ground...