Fukuoka F-61 Radar Pursuit (1948)

Background

In the immediate postwar years the U.S. Air Force flew night-fighter patrols over occupied Japan, and the F-61 Black Widow was among the aircraft equipped with airborne intercept radar. The Fukuoka incident is one of the earliest UFO reports in which an unidentified target was tracked on an aircraft's radarscope rather than seen by eye alone, which is why it recurs in the radar-visual literature.

The encounter

According to the Blue Book file as summarized by ufology researchers, the F-61's radar picked up a target at roughly 6,000 feet and about 10 miles range, moving near 200 mph, shortly before 11:05 p.m. The crew closed on it. Each time the Black Widow approached, the object accelerated sharply; Edward Ruppelt, who ran Blue Book, gave the speed as an estimated 1,200 mph and the closest approach as about 12,000 feet. On one pass the crew saw a silhouette against a near-full moon: bullet-shaped, perhaps 20 to 30 feet long, with a squared-off tail and no visible exhaust. In one follow-up account the object turned 180 degrees and dived beneath the aircraft before disappearing from the scope.

USAF ground radar stations at Shigamo-Shima and Fukae-Shima tracked the F-61 intermittently through ground clutter but never obtained a return from the unknown target.

Investigation and classification

Blue Book filed the case as number 218 and classified it 'Unknown'. Ruppelt later described it as one of the first cases in which an unidentified object appeared on a radarscope, while noting that other cases have since claimed the same distinction. Physicist James McDonald, in his later review, stressed that the official file contains reports that do not fully agree with each other on the number of objects, the closure distances and the altitude. He also cited a 1966 congressional hearing at which a Blue Book officer said the Air Force had 'no radar cases which are unexplained'; J. Allen Hynek, the Air Force's scientific consultant, was present and did not correct the statement.

The discrepancies matter. Sources disagree on whether one or several objects were involved, on whether the crew saw one object or six, and on the witness names. Some accounts cite a different catalogue number (UNICAT 273). Without the original file in hand, the specific speeds and distances should be treated as witness estimates as relayed by later writers rather than measured values.

Why it still matters

Fukuoka is cited in debates about whether radar-tracked anomalies can be dismissed as misreadings. Skeptical readings point to ground clutter, the known limits of 1948 airborne radar, and the difficulty of estimating speed and size at night. Supporters point to the agreement between radar and visual observation and to the ground stations' independent failure to confirm the target. The case remains a frequently cited example of an unresolved early radar-visual report, and it sits alongside other 1948–1950s Blue Book radar cases that were never fully explained.