I fly the A320?A320 and just looked through the flight manual. This is really a good question. It appears as if I have to agree with the other Airbus pilots: Heading (and we use magnetic heading like anybody else) is said to be produced by the Inertial Reference part of the system. A little something out of the limitations section of our flight manual: Inertial reference system: Ground alignment of the IRS has been demonstrated to be satisfactory below 70 degrees North latitude. In the NAV mode(note: our normal navigation mode), the IRS provides valid magnetic heading only between 73 degrees North and 60 degrees South .......