The advanced Russian Su-57 stealth fighter that crashed on Tuesday is reported by local media as the first serial production example. The first Su-57s were due for delivery to the Russian Air Force in just a few days. The plane designed to rival the US F-22 Raptor was executing a flight test in the Russian far east. The pilot ejected safely over woodland. It was the first total loss of the state-of-the-art Su-57. A Russian Defense Ministry outlet said the plane exploded when it hit the ground and was totally destroyed. Other media disagree on the cause: some say it was a failure in the engine control system; others trouble in the flight control system.