A disk drive comprising a moveable head, a disk, and a servo controller to
control track following operations including implementing an estimation
filter is disclosed. The disk includes a plurality of tracks in which a
substantial majority of the tracks include a plurality of servo sectors
utilized in track following operations. The servo controller implements
an estimation filter and performs operations that include: determining a
current position estimate of the moveable head relative to the track;
predicting a subsequent position estimate of the moveable head relative
to the track based upon the current position estimate; and determining
whether the predicted subsequent position exceeds an error threshold.