A method for operating a head-mounted display device is presented. An RF face tracking system is operated at a first, lower power level. Based at least on an output of the RF face tracking system while operating at the first, lower power level, a first likelihood is determined that the head-mounted display device is positioned on a head of a user. If the first likelihood is greater than a first confidence threshold, the RF face tracking system is operated at a second, higher power level. A second likelihood that the head-mounted display device is positioned on the head of the user is determined based at least on an output of the RF face tracking system while operating at the second, higher power level. If the second likelihood is greater than a second confidence threshold, an eye-tracking system of the head-mounted display device is activated.