Rotor angle instability (out-of-step or transient instability) in the power system is an immediate predicament to the safe operation of the system. The out-of-step condition left untreated may escalate into a widespread outage. Identification of the out-of-step condition is a necessary precursor to the power system operation tools such as controlled islanding to prevent system-wide collapse. The controlled islanding needs system-wide consideration for an effective mitigation plan. The conventional out-of-step detection is often devised without considering the wide-area scenario. A wide-area out-of-step identification approach based on frequency measurements is evaluated in this paper. Most of the times, the out-of-step results disconnection of equipment or part of the system. Hence, the proposed approach allocates priority to avoid false detection thus preventing unnecessary system separation or disconnection. The methodology proposed is thoroughly verified for accuracy and performance using the 68-Bus system. © 2018 IEEE.