The traditional method of glide height measurement is used for avalanche height evaluation. The air-bearing surface (ABS) of the avalanche head is assumed to be perfectly flat. This assumption, however, is not appropriate for today’s drive. In addition, a glide avalanche head normally has a different surface finish than that of a real recording head. So what an avalanche head is “seeing” on the disk surface may not be what a real head “sees” in the drive. Therefore, it becomes extremely important that one can correctly report the true avalanche height. In this study, we proposed one possible way of doing so by correctly calibrating the flying height of a glide head and the defining glide avalanche contact as “0.02% bearing depth.”