TOKYO — A missing Japanese army helicopter carrying 10 crew members is believed to have crashed into the sea off a southern island after objects appearing to be aircraft parts were spotted in the area, an official said Thursday. The UH-60JA Black Hawk helicopter disappeared from radar on Thursday afternoon while on a reconnaissance mission north of Miyako island, the head of the Ground Self Defense Force, Yasunori Morishita, said at a news conference. NHK public television earlier said the helicopter disappeared from radar about an hour after it departed from Miyako island and about half an hour before its scheduled return