NHK has learned that the pilot of the helicopter air ambulance involved in a fatal accident reportedly said that he heard an unusual sound right before the aircraft began to lose altitude.



The air ambulance went missing on Sunday off Nagasaki Prefecture in western Japan and was later found floating in the sea. Of the six people on board, the patient in her 80s, her son and a doctor died. Three others, including the pilot, are now receiving treatment.



The pilot reportedly told the aircraft operating company, SGC Aviation, that he heard the sound from the rear when the helicopter was flying at an altitude of about 150 meters.



The pilot also reportedly added that it was a noise he had never heard before, like metal being torn apart or something being sucked into a toilet.



He also reportedly said that the helicopter began to descend soon after he heard the sound, so he focused on controlling the aircraft.



Investigations by the Japan Transport Safety Board suggest that the helicopter landed on the water with the rotor still spinning. It is continuing its investigation.