Disk drive compensating for radial phase change of repeatable position error due to servo writing from spiral tracks

A disk drive is disclosed comprising a head actuated over a disk comprising a plurality of servo sectors defining a plurality of tracks, wherein the servo sectors are written to the disk by servoing off of spiral tracks. The head is positioned over a target track in response to the servo sectors, and coefficients of a first sinusoid are generated corresponding to the target track, wherein the first sinusoid corresponds a repeatable position error of the head relative to the target track. The coefficients of the first sinusoid comprise a coherent component due to a repeatable runout of the disk and a spiral component due to writing the servo sectors by servoing off of the spiral tracks, where the spiral component varies based on a radial location of the head. The head is servoed over the target track in response to the coefficients.