A drone developed at a cost of ¥2.5 billion sank at sea off Iwoto Island during a test flight Friday after engine trouble, following another drone sinking in February, the Defense Ministry said Saturday.
The ministry's Technical Research and Development Institute said the engine of the drone, developed as a reconnaissance aircraft, stopped shortly before 9:30 a.m. Friday after it went on a test flight from the Maritime Self-Defense Force base on the island, about 1,200 km south of Tokyo.
The institute guided the plane into the sea about 9 km off the island by remote control about 2 minutes later for safety reasons, it said.
While the drone was carrying capsulated radioactive material called Krypton-85, the amount is too small to harm the environment or affect human health, it said.