A method of operation of a navigation system includes: receiving acceleration information, including an acceleration measurement, and location information; calculating a total acceleration magnitude, having a vertical acceleration magnitude and a horizontal acceleration magnitude, from the acceleration measurement; calculating an average velocity estimation from the location information; calculating an average acceleration estimation from the location information; calculating a component angle between the average velocity estimation and the average acceleration estimation; calculating a forward acceleration and a lateral acceleration with the component angle and the horizontal acceleration magnitude; and generating a motion classification for a travel acceleration based on the forward acceleration and the lateral acceleration for displaying on a device.