April 19, 1953 — Old Baldy and Pork Chop Hill area, Korea
1:00 p.m. Four US Army reconnaissance observers (including pilot Lt. Julius T. Morgan, Lt. James O. Rymus, and Lt. Jack E. Myers) in two aircraft see a white, rounded, delta-shaped object 5–7 feet in diameter flying at 60–80 mph with a “vibrating” motion over Communist territory in Korea. An official G-2 Intelligence Report says the object is in the Old Baldy (Hill 266) and Pork Chop Hill areas. Radar supposedly tracks them also moving faster than sound (>767 mph). [Eberhart]
Sources:
“Small ‘Delta-Shaped Object’ Sighted over Commie Lines,” Eugene (Oreg.) Register-Guard, April 20, 1953, p. 2;
https://www.newspapers.com/article/the-register-guard/145660508/
“Four Airmen Spot ‘Discs’ Over Korea,” Kingston (Tenn.) News, April 20, 1953;
“Airmen In Korea See Flying Discs,” Harrisonburg (Virg.) Daily News Records, April 20, 1953, pp. 1,4;
“Discs Reported Flying Over Japan By U.S. Army Airmen,” Oneonta (N.Y.) Star, April 20, 1953, p. 1;
https://www.newspapers.com/article/the-oneonta-star-oneontastar19530420/192907382/
“Troops Sight ‘Delta-Shaped’ Objects In Sky Over Front,” Pacific Stars and Strips, April 20, 1953;
“Discs Spotted Over Korea,” Portland (Oreg.) Oregonian, April 20, 1953, p. 1;
https://www.newspapers.com/article/the-oregonian-theoregonian195304201/192907539/
Brad Sparks, Blue Book Unknowns Catalogue, Case 961, p. 199;
Jennie Zeidman, “I Remember Blue Book,” IUR 16, no. 2 (Mar./Apr. 1991): 9;
NICAP, [news clippings]
http://www.nicap.org/docs/530419korea.pdf
There is a bluebook folder for a different case here on March 20th. I can’t find a specific BB file for this date: