The pilot of a Maritime Self-Defense Force YS-11 training plane reported that he came dangerously close to a helicopter Wednesday while flying near Kagoshima Prefecture, the Land, Infrastructure and Transport Ministry said.

Ministry officials on Thursday quoted the pilot as saying that the two aircraft were about 50 to 100 meters apart at their closest point, with an altitude differential of only 9 meters. The pilot added that, judging from its appearance, the helicopter was privately owned, the officials said.

The ministry said it was trying to identify the helicopter.

The MSDF plane, from the Shimousa base in Kashiwa, Chiba Prefecture, took off at around 11:30 a.m. for Kanoya Air Base in Kagoshima Prefecture to transport personnel.