Kaiyō Maru Radar Encounter, Central North Pacific

The first Kaiyō Maru was a Japanese government fisheries research ship, built in 1967. She was 91.67 m long, with more than 60 crew. Her bridge carried two JMA-860 radar sets, used alternately. That detail would matter.

December 18, 1984. Ten minutes after midnight in the South Atlantic, second navigation officer Kenji Funato watched a yellowish light move away from near Orion. Eight came, roughly ten minutes apart. Some swung back and forth or zigzagged, and two briefly flared. Researcher Mikio Naganobu followed the eighth through binoculars as it sank slowly, as if dancing, then accelerated east and vanished.

In December 1986 the ship was bound from Tokyo for a survey off California. On December 21 her noon position lay about 570 km north of Wake Island and about 1,400 km west of Midway. Sunset came at 17:06.

Around 18:00 second officer Yōji Sasaki saw a huge oval echo about 5 km to port. Binoculars showed nothing. No lights, no sound. It moved away north. At the 20:00 handover he told the next watch: "There's something there, but I don't know what it is."

About 20:30 a weak, blinking echo appeared on the other set. It came in from ahead and circled the ship twice. Then it made a sharp turn and came straight at the ship, covering about 5 km in roughly 4 seconds, then reversed. A second, similar echo sat motionless off the port bow. Both left the screen at 22:40.

Near midnight an echo appeared astern and rushed in. Accounts put it at 23:10 or 23:40. Despite the moon, nothing was visible. On the screen it merged with the ship and vanished, apparently above the radar beam.

In that moment the bridge heard a roar. Helmsman Mikio Takayanagi rendered it "Bu-ohh", third officer Masaaki Shimojō "Doo-on". It was the sound of something cutting through the air, with no shock wave and no vibration. Seaman Masanobu Muratsuka looked toward the bow and saw a very bright, reddish-yellow flash near the horizon, shaped like a crushed egg. It lasted one or two seconds, and nobody else saw it.

Captain Shinnosuke Sueki had heard the sound in his cabin. He phoned the bridge: "Was it a plane? Of course it must have been a plane?!" At 23:45 a last large echo appeared to the south-west and faded within about five minutes.

Naganobu, then with the Japan Marine Fishery Resources Research Center, was not aboard but investigated afterwards. The echo suggested an object of about 300 m, at 500 m or less, moving at about 5,000 km/h. On January 2 and 3, 1987, a US Navy P-3C flew over the ship. It looked and sounded completely different. On March 25, 1988, engineers from the radar maker ruled out a fault and beacon effects. In the Japanese edition of Science in September 1988, he gave five reasons it was no aircraft: the echo's size, its speed and sharp reversal, no navigation lights, no engine noise, and the flash.

No hoax claim and no published sceptical analysis have surfaced. Radar quirks, an unlit military aircraft or a meteor are the obvious questions, though the echoes showed on two separate sets. Naganobu concluded these were flying objects not seen by eye but captured by radar, and among 50 to 60 long-voyage mariners he found three similar unreported encounters. The case came barely a month after Japan Air Lines Flight 1628 over Alaska. Today it survives mainly through Jun-Ichi Takanashi's write-up, reposted in German on Allmystery.