Abstract: The method involves the steps of moving the magnetic head (8) to within aerodynamic distance from the electrically conductive surface (16) of rotating magnetic recording disk, further positioning of the head (8) until a tunnel current occurs across the gap between the head (8) and surface (16), and maintaining said tunnel current constant by using the deviations of the current from a predetermined value corresponding to a certain flying height.The apparatus comprises a tunnel electrode (9) forming an integral part of the head assembly which is attached to a distance control mechanism (5) permitting the positioning of the head assembly with a one-nanometer accuracy. The tunnel electrode (9) has a very slightly beveled shoulder (45, 47) ensuring early detection of asperities approaching the head. Gradation of the potential between tunnel electrode (9) and surface (16) of the recording disk (3) is used to enhance the response to asperities.