Abstract: Method and apparatus for testing tracking accuracy in a disc drive are disclosed. Each head and each track is treated as a unique entity. Each track has an inherent window margin. Stored data is read by a head skewed (or delayed) in the window toward one edge of the window until errors are encountered. The data is then advanced toward the center 5% of the bit cell past the point at which errors are not encountered. With the data positioned in the window 5% from it's failure point, any noise or media defects will cause the data bits to fall out of the window and thus cause an error. Any soft errors that repeat in the same byte area are logged as hard errors. This testing method accomplishes both a defect mapping test and soft error rate test in one test in the least amount of time from the interface.