schuler tuning
From what I recall, terrestrial navigation systems have the earths surface geometry programmed into them, eg as you travel the 'inertial platform' whether physical or virtual is rotated to keep the horizontal. Errors in the horizontal plane cause a feedback which tends to negate the error (speed too high, platform over rotates past horizontal in the belief you have traveled further round the globe, gravity leaking into the accelerometer channel not properly accounted for causing speed estimate to decrease). Called schuler tuning and has period of 80+ mins.
Everything moving that is observed from earth's surface seems to be affected by the coriolis force, including aircraft. Perhaps the nav systems compensate also. Dunno, but it is proportional to speed so an issue for artillery more than aircraft.