Modern aircraft no longer use magnetic compass systems, except of course for the standby. The Inertial Reference Unit calculates TRUE heading based on the North Pole. Magnetic heading is calculated by adding or subtracting from the TRUE calculation based on aircraft position and an internal database. On an Airbus, magnetic heading is displayed up until 82.5 degrees North. Above that latitude, the IR displays TRUE heading only. (This also occurs in the vicinity of the magnetic pole 'keyhole area'). A GRID Track reference is also displayed on the Nav Display at this time. Basically, with the compass referenced to TRUE, one would fly 360 to the Pole, and 180 from the pole. Oh yeah, leave NAV mode engaged and let the Flight Management take care of your routing, because from the North Pole, all roads lead South!