September 18, 1948 — Shreveport, LA
5:00 p.m. A draftsman at home near Shreveport, Louisiana, while using high-power binoculars to watch an L-6 aircraft at 10,000 feet altitude at 60° elevation to the southeast traveling 100 mph on Air Force Day, sees a bright white, aluminum-colored, half-spherical object traveling the opposite direction in level flight at about 20,000 feet, 2.5 miles away. It is moving at 100–150 mph heading south, leaving no trail. He loses it when he tries to view it without binoculars. The object appears to be one-third the size of the L-6 (35.5 feet) but twice the distance, or about 24 feet. [Eberhart]
Solution (it was a balloon, this is yet another case Sparks for some reason incorrectly calls an Unknown)
Sources:
Brad Sparks, Blue Books Unknowns Catalogue, Case 114, p. 38;
[PURSUE release, p. 2;]
https://www.war.gov/medialink/ufo/release_1/38_143685_box7_incident_summaries_173-233.pdf