A present invention discloses a method for performing forward error correction (FEC) in long-haul submarine transmission systems. Data is encoded at a transmitter by serially concatenated, binary Bose-Ray-Chaudhuri-Hocquenghem (BCH) error correcting codes. The invention encodes a stream of data employing a plurality of serially concatenated, binary Bose-Ray-Chaudhuri-Hocquenghem (BCH) error correcting codes, arranging data into a frame of parallel data blocks (the outer frame) with redundancy bits appended by a BCH(3896, 3824) code; the outer frame is then interleaved to produce a frame of serial data blocks (the intermediate frame); and the final frame (the inner frame) is produced by appending the redundancy bits of the BCH(2040, 1952) code to the intermediate frame. The data, once encoded, is transmitted across a datapath and decoded at the receiver.