Upon the occurrence of out-of-step (OOS) phenomena due to severe fault in the system, it is advisable to initiate force generator tripping as soon as possible within a few cycles while maintaining system stability. Due to this requirement, a fast OOS detection method is the most critical criterion. This paper analyses system behavior at selected study area in 790 Bus Test System Network using PSSE software to justify that TSI COI Speed can serve as an indicator to detect OOS at early stage in order to initiate Force Generator Tripping Scheme (FGTS). In this paper, TSI COI Speed and Accelerating Power are used as a new technique to be implemented in FGTS; a complete algorithm is developed that can detect OOS, initiate FGTS, calculate the amount of MW quantum to force trip generator, determine which generator and the most suitable location to force trip generator, evaluate on the effectiveness of FGTS, and initiate contingency action to take if OOS still exists in the system.