An uplink signal-to-interference ratio for each of multiple mobile radio terminal connections supported in a cell in a cellular communications system is estimated. A signal-to-interference ratio error is determined for selected ones of the estimated uplink signal-to-interference ratios. One or more signal-to-interference ratio errors are identified that exceed a signal-to-interference ratio error threshold. An instability indicator associated with the cell is determined based on the one or more identified signal-to-interference ratio errors. A load control decision and/or a decision for scheduling one or more uplink mobile radio transmissions in the cell may then be made based on the instability indicator, e.g., to prevent a transmission power rush in the uplink in the cell and/or to efficiently use available resources for uplink transmissions.