Four documented cases from September 17–30, 1952.
1952: September 17th–30th
UFO|UAP & Entity Sightings Archive
The back half of September 1952 is dominated by Operation Mainbrace, the large NATO naval exercise that produced a cluster of well-documented radar-visual and pilot sightings across the North Sea and northern Europe — including RAF pilot John Kilburn’s famous “falling sycamore leaf” pursuit and a photographed object from the deck of the USS Franklin D. Roosevelt. This page covers September 17th through 30th; see the companion page for September 1st–16th.
Date: Sept. 17, 1952 (BBU 2105)
Location: Tucson, Arizona
Time: 11:40 a.m.
Summary: Mr. and Mrs. Ted Hollingsworth saw two groups of three large, flat, shiny objects fly in tight formations — the first group slow, the second faster. Duration about 2 minutes.
Source: Berliner
Date: Sept. 20, 1952
Location: Denmark and Norway (Operation Mainbrace, NATO exercise)
Time: Beginning around 4:00 p.m.
Summary: Personnel of the U.S. aircraft carrier USS Franklin D. Roosevelt, participating in the Mainbrace maneuvers, observed a silvery, spherical object moving across the sky behind the fleet; it was also photographed by reporter Wallace Litwin, whose color photographs were examined by Navy Intelligence officers but never made public. The ship’s weather officer noted a balloon had been launched at 3:30 p.m. that rose out of sight into overcast in about 50 seconds. (Some secondary sources give an incorrect date of September 19 for this sighting.)
Source: Richard Hall, Dan Wilson
Date: Sept. 20 (or 19, or 21), 1952
Location: Topcliffe RAF Station, Yorkshire, England, UK
Time: 10:53 a.m. (or possibly 4:14 p.m.)
Summary: During Operation Mainbrace, RAF Meteor jet fighter pilots Flt. Lt. John W. Kilburn and Flt. Lt. Cybulski were descending to land at 5,000 ft when they saw a slow-moving, circular, silver (or white) object about 5 miles behind them at roughly 15,000 ft, following a similar course. The object began swinging like a “falling sycamore leaf” or pendulum and descending; as the Meteor turned toward Dishforth, the object followed, then stopped its falling-leaf motion, began rotating on its axis, and suddenly accelerated at “incredible speed” — faster than a meteor — to the west, then turned southeast and disappeared. Ground observers, including Flying Officer Paris, Master Signaller Thompson, and Higgins, along with five other aircrew, also witnessed the object. Duration 15–20+ seconds.
Source: Jan Aldrich; Ruppelt pp. 195–6; NICAP; FUFOR Index
Date: September 21, 1952
Location: Morocco
Time: Unknown
Summary: Unknown — no further detail survives in the sourced record.
Source: Margaret Sachs, “The UFO Encyclopedia”
Date: Sept. 21, 1952 (approximate)
Location: North Sea, near England, UK
Time: Unknown
Summary: During Operation Mainbrace, six British pilots flying a formation of Meteor jets pursued a shiny, spherical object, losing it for 1–2 minutes before it reappeared, following one of the jets; that pilot turned to pursue, but the object outmaneuvered him. Duration several minutes.
Source: Ruppelt p. 196; BB files; FUFOR Index
Date: Sept. 22, 1952
Location: Not recorded
Time: Not recorded
Summary: Police observed 3–4 UFOs maneuvering erratically.
Source: UFOE, VII
Date: Sept. 23, 1952 (BBU 2119)
Location: Gander Lake, Newfoundland, Canada
Time: Not recorded
Summary: The Pepperrell AFB operations officer and seven other campers saw a bright white light, reflected on the lake surface, fly straight and level at about 100 mph. Duration 10 minutes.
Source: Berliner
Date: Sept. 24, 1952
Location: Aurora, Colorado
Time: 3:15 p.m.
Summary: USAF T/Sgt. B. R. Hughes saw 5–6 circular objects, bright white but not shiny, circling in trail formation. Possibly the same event as the September 30 Denver case listed below. Duration 5–6 minutes.
Source: Berliner
Date: Sept. 24, 1952 (BBU 2121)
Location: Charleston, West Virginia
Time: 3:30 p.m.
Summary: The crew of a USAF B-29 bomber saw a large number of bright, metallic particles or flashes, up to 3 ft in length, streaming past the aircraft. Duration 15 minutes.
Source: Berliner
Date: Sept. 24, 1952
Location: Guantanamo Bay, Cuba
Time: 7:45 p.m.
Summary: A U.S. Navy crew aboard a TBM-1S aircraft chased an orange light with a greenish tail.
Source: Weinstein
Date: Sept. 26, 1952 (BBU 2126, Chop Clearance List Item #22)
Location: 400 miles NNW of the Azores Islands
Time: 11:16 p.m.
Summary: The pilot, copilot, engineer, and aircraft commander of a USAF C-124 transport plane saw two distinct green lights to the right and slightly above the aircraft; at one point they seemed to turn toward it, alternately leading each other. Duration over 1 hour.
Source: Berliner
Date: Sept. 27, 1952
Location: Hempstead, Texas
Time: Unknown
Summary: Two USAF T-33 pilots saw a white-silver, circular, flat disc flying erratically at 600–700 mph.
Source: Weinstein
Date: Sept. 27, 1952 (BBU 2128)
Location: Inyokern, California
Time: 10 p.m.
Summary: Two couples, using a 5x telescope, saw a large, round object that cycled through the color spectrum every 2 seconds, flying straight and level. Duration 15 minutes.
Source: Berliner
Date: Sept. 28, 1952
Location: Tsushima Island, Japan
Time: Unknown
Summary: Unknown — no further detail survives in the sourced record.
Source: McDonald list
Date: Sept. 28, 1952
Location: Goose Bay, Labrador, Canada
Time: Unknown
Summary: An object resembling an aircraft, traveling north to south at approximately 120 mph, was seen on GCA radar as it passed 1.5 miles east of runway 27. Due to the GCA unit’s limitations, the object had to be below 4,000 ft altitude; the signal was strong and clear.
Source: McDonald list
Date: Sept. 29, 1952 (BBU 2136)
Location: Rochester, England, UK
Time: 3:55 p.m.
Summary: Witnesses unknown; the report came via the Rochester Police Department, describing two flat objects hovering, then speeding away. Duration 3 minutes.
Source: Berliner
Date: Sept. 29, 1952 (BBU 2140)
Location: Southern Pines, North Carolina
Time: 8:15 p.m.
Summary: U.S. Army Reserve 1st Lt. C. H. Stevens and two others saw a green ellipse with a long tail, orbiting. Duration 15 minutes.
Source: Berliner
Date: Sept. 30, 1952
Location: Edwards AFB, California
Time: Not recorded
Summary: An aviation photographer and others observed two discs alternately hovering and darting around.
Source: UFOE, VI
Date: Sept. 30, 1952 (BBU 2138)
Location: Denver, Colorado
Time: Not recorded
Summary: Unknown — possibly the same event as the September 24 Aurora, Colorado case listed above.
Source: NARA
EXECUTIVE SUMMARY
Operation Mainbrace and the “Falling Sycamore Leaf”
The back half of September 1952 is defined by Operation Mainbrace, a major NATO naval exercise across the North Sea and northern Europe that produced several of the era’s best-documented radar-visual and pilot-witnessed cases in quick succession — a photographed sphere from the deck of the USS Franklin D. Roosevelt, a formation of British Meteor jets outmaneuvered by a shiny sphere over the North Sea, and RAF pilot John Kilburn’s now-famous account of an object swinging like a “falling sycamore leaf” before accelerating away at incredible speed over Yorkshire. Around these anchor cases sits the usual steady rhythm of pilot and civilian light reports spanning from Newfoundland to Japan.
“It began swinging like a falling sycamore leaf.”
— Flight Lt. John W. Kilburn, describing the object over Topcliffe RAF Station, Yorkshire, September 1952
