The Air Self-Defence Force confirmed on 16 September that an RQ-4B from Misawa’s 502nd Squadron had gone into the water about 50 kilometres north of Tottori after a mission that began at 10:20 local time the day before. Communications with the ground station faltered after 12:55. The radar track vanished at 12:58. Coast Guard and Self-Defence Force aircraft found floating wreckage that afternoon. Photographs from a Maritime Self-Defence Force boat made the identification firm the next morning. Japan operates three of the type, the three airframes cost about $450 million together. The ministry said the remaining surveillance posture would continue. Misawa city asked for a halt until the cause was known. Training sorties and an air-festival display were cancelled. By the weekend, wreckage had washed onto the Tottori shore and been identified as part of the same aircraft. The ASDF said the machine was not fitted with a flight recorder. That single line is the investigation.
There is no surviving crew to interview. Mission data, sensor takes and command-link logs are still inside a classified architecture that belongs to Japan and by design heritage to the United States manufacturer. The lead authority is the Air Self-Defence Force’s own accident committee, not the Japan Transport Safety Board. Annex 13 does not automatically open a civil file over a military reconnaissance aircraft on a duty flight in international waters. Northrop Grumman and the U.S. Air Force may be invited as technical parties. What they may say in public is another question. Families are not waiting at a terminal. Coastal towns are waiting to know whether more composite and fuel will come ashore. That is a different accountability clock.
What can be recovered is not the same as what can be published. Floating structure, a wing or tail piece, an engine inlet and a shore find give attitude at impact and a materials story. The useful evidence is on the ground at Misawa. The last healthy telemetry, the moment the link failed, whether the aircraft was in a lost-link profile, and the maintenance history of that tail. Deep water off Tottori will not surrender a civil-style cockpit voice because there was none. A hard disk that went down with the fuselage is a navy recovery problem, not a beach walk. Anything that reconstructs the sensor picture is likely to stay inside the defence ministry. Civil uncrewed-aircraft investigators can learn only the unclassified residue that points to lost-link behaviour, the absence of a crash-protected recorder on a large UAV and the time it takes a state to confirm that floating white composite is in fact the missing aircraft.
The honest first product is therefore modest. Confirm the last command, the last health word and whether a lost-link procedure was running. Publish a factual sequence that does not describe the reconnaissance task. Say whether the other two airframes share a part or a software load that should be grounded. Until that note exists, Japan has a hole in a three-aircraft fleet and a reminder that high-altitude uncrewed aviation can disappear without a black box for anyone else to read.