An approximate model is proposed for simulating head-to-tape spacing in helical scan video tape recording. The particular issues focused on in the paper are the effect of the variability of scanner to tape spacing along the helix as well as the effect of the head contour. From scanner-to-tape air film values, the paper deduces the relation between head and tape at the recording track and predicts the RF envelope shape. The important goal accomplished in the paper is to provide an explanation and a model for the phenomenon of development of taper in the RF envelope.Presented as a Society of Tribologists and Lubrication Engineers paper at the ASME/STLE Tribology Conference In Toronto, Ontario, Canada, October 8–10, 1990