A satellite communications system having a fallback mode of operation, during which uplink signals are transmitted at a reduced data rate, is provided with a novel fallback mode ingress/egress mechanism utilizing a combination of a feedback-based fade detection scheme and fade detection based on parameters independent of the uplink signal transmission. The fallback mode ingress/egress mechanism is responsive to a satellite beacon signal independent of the uplink signals and to feedback signals produced by the satellite in response to the uplink signals, for requesting a satellite terminal to switch into the fallback mode when either the feedback signals indicate an increase in a fade level or in response to a first value of a selected parameter of the satellite beacon signal. The fallback mode ingress/egress mechanism requests the satellite terminal to switch out of the fallback mode in response to a second value of the satellite beacon signal parameter.