The Sioux City Mystery Plane

Sioux City, Iowa. Saturday, January 20, 1951. Mid-Continent Airlines Flight 9, a DC-3 bound for Omaha, was leaving the municipal airport. In command was Captain Lawrence W. Vinther, a former Army Air Forces cadet instructor with more than 8,000 flying hours. His co-pilot, James F. Bachmeier, was a Naval Air Reserve lieutenant commander with over 6,000. Among the passengers were an Air Force colonel, Matthew Thompson, and his aide.

It was shortly after 8:30 PM by most accounts. The night was clear and cold. In the tower, chief controller John M. Williams had been watching an oddly maneuvering light high in the west. Then it abruptly accelerated, "in a manner clearly precluding either meteoric or aircraft origin," as James E. McDonald later put it. The tower placed it at about 8,000 feet. Vinther saw it too, moving from north to south, west of the field. He began a left climbing turn to follow.

Southeast of the field, the light blinked five or six times. Vinther radioed and asked the unknown pilot to blink again. It did. Then it came at them. The object dived over the airliner's nose, about 200 feet above it. "In a split second it closed in and flashed by their right wing," wrote Edward J. Ruppelt. Both pilots thought they would collide. It passed silently, at great speed.

When Bachmeier recovered and looked out his side window, it was there. Flying formation. Same direction. Same altitude. Same speed. About 200 feet away. "You can't turn ordinary planes that fast!" Vinther said.

In the moonlight they saw its silhouette. A cigar-shaped fuselage like a B-29. A wing with no sweepback, "perfectly straight." No engine nacelles. No jet pods. Apparently no tail. It was as large as a B-29, or half again as big. After four or five seconds it dropped under the fuselage and was gone to the northwest. Vinther turned west, then right. There was no further contact.

Air Force OSI agents from Offutt Air Force Base took statements from both pilots, from Williams and from fellow controller Millard H. Keenan. The case reached the Air Technical Intelligence Center before Project Blue Book had its name. Ruppelt learned of it on his second morning there. The investigating officer had found a B-36 somewhere in the area and was trying to blame the sighting on it. The file also names the C-99. Accounts differ on the colonel. One says he was asleep. Ruppelt calls him "mighty impressed."

Ruppelt rejected the bomber outright. A B-36, "even one piloted by an experienced idiot, could not do what the UFO had done," he wrote. Still, the B-36 did have long, nearly straight wings. The crew first suspected something secret. Bachmeier later told McDonald he had felt "it had to be some kind of secret device." But, McDonald added, "in the ensuing 17 years, we have not heard of any aircraft that can execute instantaneous course-reversal." Even the final label is disputed. NICAP records it as closed as a B-36. Others list it as unknown.

Vinther told his story in FLYING magazine in June 1951, as "Another Saucer Mystery." LIFE featured it in 1952. Ruppelt retold it in his 1956 book. On July 29, 1968, McDonald presented it to a symposium of the House Committee on Science and Astronautics. The papers of researcher Richard F. Haines hold a folder on Vinther and Bachmeier. McDonald's question still stands. What aircraft can reverse course in an instant?