Abstract: A helical scan magnetic tape recorder includes a rotary magnetic head scanner and a received magnetic tape cassette including spaced coplanar supply and take-up reels having magnetic tape spooled on the reels with a span of magnetic tape extending between the reels. Supply and take-up vacuum cavities are located contiguous to and on respective opposite sides of the scanner. Supply and take-up capstans are spaced from the rotary head scanner located in a tape transport path between the vacuum cavities and the tape cassette. Magnetic tape is initially removed from the cassette and moved to a tape vacuum loading position where it partially contacts the rotary head scanner, by a mechanical threading device. Thereafter, vacuum is applied to the vacuum cavities to draw the tape into contact with the vacuum cavities to substantially wrap the tape around the rotary head scanner. The supply and take-up capstans are rotated during vacuum threading to assist drawing the tape into the vacuum cavities.