The proposed method is able to determine whether the line monitored by a relay is faulty or not using very few local measurements, making ultra-fast fault identification possible. When a fault is suspected, the proposed algorithm estimates the fault distance and impedance. The estimation process uses a parametric model describing the voltage and current evolution just after the fault occurrence based on the fault parameters. When a fault is suspected, an interactive maximum-likelihood (ML) estimate of the fault parameters is evaluated from the data available at the relay. The estimated fault parameters and their confidence intervals are exploited to determine whether or not one has to consider that a fault actually occurred in the protected line. While this algorithm has been developed for HVDC line protection, it can be implemented for AC transmission line protection.