38.48N 123.16E (Yellow Sea), October 1951October 1951

# Yellow Sea Sighting, October 1951

On the morning of October 18, 1951, a U.S. Navy patrol aircraft spotted an unidentified object over the Yellow Sea, roughly 140 nautical miles from the Chinese coast. The crew of the PBM Mariner, a twin-engine weather reconnaissance plane commanded by Ensign George Gregory, made the sighting at 0333 (3:33 a.m.) local time while cruising at 5,000 feet.

A waist gunner first noticed a bright light on the port side and alerted the pilot. The entire crew confirmed what they were seeing: a long, conical flame resembling the exhaust of a jet engine, glowing orange-red, positioned about twelve miles away according to radar confirmation. The object appeared to be flying at roughly 1,000 feet altitude. When the Mariner's pilot tried to approach and silhouette it against the full moon to take photographs, the object pulled away, maintaining its distance at twelve miles.

As the Mariner closed to about three or four miles, the crew got a better visual look using binoculars. They saw what appeared to be a large aircraft hull, estimated at sixty feet long, with swept-back wings and a dihedral angle (a slight upward bend) at the wingtips. No tail section was visible. The craft appeared to be flying at an extremely high angle of attack, about twenty-five degrees, suggesting it was a high-speed aircraft struggling to stay airborne at reduced speed. The exhaust flame changed appearance as the object maneuvered, becoming longer and white-orange in color when apparently adding power.

The object then accelerated rapidly, with radar tracking it to a range of twenty-two miles before contact was lost. Visual contact ended shortly after as clouds obscured the target. The entire encounter lasted about twenty-two minutes. Based on the Mariner's speed and the object's computed speed relative to the patrol plane, the craft was calculated to have been traveling at approximately 530 knots.

Air Force intelligence officers analyzing the report concluded the object was probably a jet aircraft, possibly a MIG-15 fighter. They noted that under moonlit conditions at night, visual limitations would make accurate observation difficult, and that certain jet aircraft could produce visible exhaust flames when flying at reduced speed with specific fuel mixtures. They also suggested that reflections of wingtips in moonlight could create unusual impressions of the aircraft's shape. The full case file of 17 pages is reproduced below as held by the National Archives.