Triangular, delta-shaped, or diamond-shaped objects have become much more prominent since J. Allen Hynek first developed his classification system—enough so that they might be considered a class in themselves. Seen as both distant shapes at day or night (often with only three lights and a presumed object that connects them) and structured objects that are much closer to the witness, triangular UFOs transcend the Hynek guidelines.

David Marler, in his Triangular UFOs: An Estimate of the Situation (2013), laid out 10 primary and 10 secondary characteristics that serve as a working profile for these objects. The 10 primary characteristics are those that are displayed in the vast majority of reports:

  1. Beams of light emitted
  2. Three large white lights at each point of the triangle, and often a central red light
  3. Extremely large size
  4. The ability to hover
  5. The ability to make abrupt course corrections without tilting
  6. Silent flight
  7. Slow speed
  8. Low-altitude flight
  9. Sharp turns at high speed
  10. Rapid acceleration

The 10 secondary characteristics are not as prevalent, but are frequently reported:

  1. Subtle noises unlike aircraft
  2. Accompanied by non-triangular UFOs
  3. Electromagnetic effects
  4. Flight in groups of two or more
  5. A colored or glowing underside
  6. Erratic movement
  7. Blunt-end forward movement
  8. Detachable, independent lights
  9. Shape transformation
  10. Detailed superstructure on the underside

Sebring, Ohio, triangleSebring, Ohio. On June 7, 1970, at about 1:30 a.m., a group of four individuals was driving from Sebring, Ohio, toward Cleveland. They first observed a bright light to the left of the road and thought it was a tower, but binoculars showed no structure. Eventually, the object came toward the road and they could see it was an equilateral triangle, moving flat side forward, with red and green lights on the front and a small white light in the rear. It was moving very slowly, never more than 20-25 mph, with no sound. The UFO eventually went high into the sky and hovered there for some time.

Original case report from Cleveland Ufology Project

Zillah, Washington, triangleZillah, Washington. At dusk on September 8, 1970, a farmer near Zillah, Washington, was dismounting from his tractor when he saw a triangular object hovering in the air. Steel gray in color, it had a red light at each of its bottom corners and white lights in its center. Also seen by four other adults and three children, it eventually moved upward and out of sight.

NICAP case file

The Eupen, Belgium, diamondEupen, Belgium. At 5:24 p.m. on November 29, 1989, about 250 witnesses, in 143 separate observations, watched the same or a similar triangular or delta-winged craft maneuvering overhead at Eupen, Belgium. Two police officers in a patrol car were illuminated by a brilliant light beam from a dark triangular object hovering at 600–900 feet and making a faint humming noise. The light was so dazzling that “we could read a newspaper under it.” The UFO moved slowly away to the southwest, where it hovered near the Lac de la Gileppe dam for 45 minutes. Policemen Heinrich Nicoll and Hubert von Montigny watched it repeatedly emit two red beams with a red ball at the spearhead of both beams; the beams soon disappeared, leaving the red balls, which returned to the object. Then around 7:23 p.m., it moved further to the southwest and was seen over Spa for 30 minutes before it disappeared.

Auguste Meessen, “The Belgian Sightings,” IUR (May/June 1991)

The St. Clair County, Illinois, trianglesSouthwestern Illinois. At shortly after 4:00 a.m. on January 5, 2000, the “St. Clair Triangle,” “UFO Over Illinois,” “Southern Illinois UFO,” or “Highland, Illinois UFO” sighting took place over the towns of Highland, Dupo, Lebanon, Shiloh, Summerfield, Millstadt, and O’Fallon, Illinois, all within the vicinity of Scott Air Force Base in St. Clair County. Five on-duty police officers around these locales, along with various other eyewitnesses, reported a massive, silent, triangular, or rectangular craft operating at unusual treetop-level altitude and speeds. The officers were able to track the object and maintain radio contact with each other throughout the event. One of the police officers managed to get a single yet ambiguous Polaroid photograph of the object. Investigator David Marler initially concluded that, despite some differences in descriptions, the reports indicated a single unknown object with bright lights flying below 1,000 feet altitude. However, later reports suggested there were as many as three objects. The incident was examined in the ABC special Seeing Is Believing with Peter Jennings, an hour-long Discovery Channel special UFOs Over Illinois, an episode of the 2004 Syfy series Proof Positive, and a 30-minute independent documentary titled The Edge of Reality: Illinois UFO, January 5, 2000 by Darryl Barker Productions.

David Marler, “Illinois Police Officers Track UFO near Scott AFB,” MUFON UFO Journal (March 2000)

The 2002 Dartmouth, Nova Scotia, triangleDartmouth, Nova Scotia. At 9:30 p.m. on March 15, 2002, Lisa Stone was driving with her 16-year-old son when she saw a triangular object with white lights that was maneuvering around Magazine Hill, outside Dartmouth, Nova Scotia. The object was massive, perhaps the size of a university football field. She drove directly underneath, and “hail” started falling from it. The object performed a figure eight before heading in the direction of Fall River to the northeast.

Don Ledger, “The Flying Triangle Phenomenon,” IUR (January 2003)