A method of setting a channel congestion message in a wireless multiple access packet data system in which the channel congestion message is broadcast on the forward channel of the system and communication over the reverse channel is in the form of bursts. The method comprises the steps of: measuring an actual fraction of undecodable bursts on the reverse channel; measuring traffic parameters of the reverse channel; predicting from the measured traffic parameters an expected fraction of undecodable bursts for optimum throughput on the reverse channel; comparing the actual and expected fractions of undecodable bursts, and; setting the congestion message according to the result of the comparison. A system for implementing the method is also provided.