Triangle craft is a descriptive category for reported UAP with triangular, delta, or boomerang-like outlines. Witnesses often describe three lights defining a broad shape, a central light, slow movement, hovering, or surprisingly little sound. Some reports instead concern a dark region inferred between separate lights. Shape is therefore an observation or interpretation, not proof that every case involves the same vehicle.

The modern pattern includes well-known episodes such as the 1989–1990 Belgian wave and the 1997 Phoenix Lights, alongside many shorter civilian and military reports. Explanations have included conventional aircraft, aircraft formations, flares, drones, stars seen through cloud, and misjudged geometry. Perspective can turn three unrelated lights into a perceived solid triangle, while darkness removes reliable cues for distance and size. Other cases remain disputed because original sensor data or precise timing is unavailable.

Official statistics confirm that the description occurs but is not dominant. The All-domain Anomaly Resolution Office publishes triangle or delta as one morphology among orbs, lights, cylinders, disks, and other forms. Its trend data do not establish common construction or origin, and reported morphology is absent from many files. Secret-aircraft theories are plausible in some defense-airspace contexts but require evidence tied to a particular platform and date.

Triangles occupy an important place between witness testimony and Exotic Propulsion speculation. Silent low-speed flight and sudden acceleration, if measured rather than inferred, would have major engineering implications. Most public accounts lack the range, calibrated imagery, radar, acoustic data, and metadata needed to establish those performance claims. The category is useful for comparing reports as long as visual resemblance is not mistaken for identity or a shared manufacturer.