(Reuters) - Boeing Co said on Friday it had recorded reach-forward losses of $2.31 billion related to the U.S. Air Force KC-46A aerial refueling tanker over 2016, 2017 and 2018, bringing the total pre-tax cost of the program to $3.6 billion. The world's largest planemaker said in a filing that in 2018, it had recorded reach-forward losses of $736 million on the contract, reflecting higher estimated costs related to certification, flight testing and change incorporation on aircraft, among other things. The U.S. Air Force recently accepted the long-delayed first delivery of the KC-46 tanker jet made by Boeing. Delivery means Boeing could begin to reverse what has been a steady stream of financial losses related to the KC-46 program, and a major public relations headache for Chicago-based aircraft manufacturer. The delays and fixes for the program have been costly for Boeing and the company had recorded charges on the tanker program. The losses bring the total pre-tax cost of the program to $3.6 billion, or $2.4 billion after taxes, Boeing said. (Reporting by Divya R in Bengaluru; Editing by Anil D'Silva and David Gregorio)