A preliminary report released by the National System Operator has revealed the sequence of events that led to the total system failure on October 17, 2026. The nationwide blackout initiated at 11:43:29 hours under dry and sunny weather conditions, culminating in a complete collapse of the power system within thirty seconds at 11:43:59 hours.According to the findings, the incident was triggered when Lakvijaya Power Plant Unit 01 rapidly de-loaded from a net generation of 187 megawatts to 5 megawatts within 450 milliseconds due to a drum level low condition. This sharp drop caused the system frequency to plunge from 49.906 hertz to 48.75 hertz within just two seconds. The sudden frequency collapse prompted the rejection of non-dispatchable generation resources and the subsequent operation of all five stages of the under-frequency load shedding protection scheme.Almost all dispatchable generating units tripped due to under-frequency or under-voltage protections, with the exception of Victoria Unit 03 and Old Laxapana Stage I and II, which remained spinning at no load. System restoration commenced immediately following standing instructions, beginning with the synchronisation of Kotmale Unit 01 at 12:11 hours.Power restoration proceeded simultaneously across four main systems, including the Mahaweli, Laxapana, Samanala, and Colombo systems. The recovery of the entire national transmission system was completed within five hours and fifteen minutes.While grid recovery was swift, certain thermal and combined cycle power plants experienced minor auxiliary, turning gear, or cold startup sequence issues that temporarily delayed their full contribution during re-energisation.