Sighting waveBelgian Triangle Wave (29 November 1989 – April 1990)

aka Belgian Triangle Wave (29 November 1989 – April 1990)

A five-month wave of triangular-craft sightings over Belgium was tracked on the night of 30–31 March 1990 by ground radar at Glons and Semmerzake and by airborne F-16 radar; the Belgian Air Force released the radar data and gun-camera imagery publicly.

phenomenologically-open Multi-month wave with F-16 radar lock + visual confirmation by Belgian Air Force; gendarmerie reports; Belgian MoD officially acknowledged unidentified status.

status history (1)

2026-06-09 · unannotated → phenomenologically-open — annotated before the 2026-06-09 sweep; history begins at seeding

Eupen, eastern Belgium, where gendarmes reported the wave's first mass sighting on 29 November 1989 Wikipedia Commons · CC BY-SA 4.0 · Horst J. Meuter · 2019

Belgian Air Force F-16, the type scrambled against radar contacts on the night of 30-31 March 1990 (2014 photo) Wikipedia Commons · CC BY 2.0 · Clemens Vasters · 2014

Beginning the evening of 29 November 1989 over Eupen, Belgium, gendarmes Heinrich Nicoll and Hubert von Montigny were among the first official witnesses to a slow-moving, low-altitude triangular craft. Over the following five months, the Belgian gendarmerie collected more than 2,000 written reports. On the night of 30–31 March 1990, two F-16s from the Belgian Air Force’s 1st Wing at Beauvechain were vectored to intercept targets that had been confirmed by NATO radar at Glons and Semmerzake. Both F-16s’ AN/APG-66 radars achieved lock at one point; lock was broken almost immediately, then re-acquired and broken several times over the course of an hour. Maj. Gen. Wilfried De Brouwer, the Belgian Air Force’s Chief of Operations, held a press conference confirming the events and releasing radar tracks publicly — a step taken by no other Western military with respect to a UFO investigation in the 20th century.

Notable & intriguing

On the night of 30–31 March 1990, two Belgian Air Force F-16AM aircraft were vectored to intercept targets detected simultaneously by NATO ground radar at Glons and Semmerzake and by airborne F-16 radar; the targets achieved acceleration peaks of 40 g, beyond the structural tolerance of any known crewed aircraft.

Belgian Air Force official report, 11 July 1990; Maj. Gen. Wilfried De Brouwer, Chief of Operations, press conference, 11 July 1990
The Belgian Air Force, under Chief of Operations Maj. Gen. Wilfried De Brouwer, publicly released the F-16 radar tracks and the official investigation conclusions — the only Western military authority to do so during the 20th century with respect to a UFO investigation.

Belgian Ministry of Defence report, 11 July 1990; SOBEPS, Vague d’OVNI sur la Belgique, vols. 1–2, 1991/1994
Belgian gendarmes Heinrich Nicoll and Hubert von Montigny filed the first formal triangular-craft report at 19:15 on 29 November 1989 in Eupen; over the next five months the gendarmerie collected 2,000+ written witness statements, the largest single national-police UFO archive ever assembled in Western Europe.

Belgian Gendarmerie reports, 1989–1990; SOBEPS, Société Belge d’Étude des Phénomènes Spatiaux, archives

Public-record items already documented about this subject. Folklore is labelled. Sources cited where the specificity warrants it.

Suggested watching

UFOs: Generals, Pilots and Government Officials Go on the Record (2010) documentary

dir. James Fox / Leslie Kean · various · 1h 40m

Major General De Brouwer of the Belgian Air Force on camera, recounting the 1989–1990 triangle wave and the F-16 radar lock.

essential for the official-record material

Appears in interpretive theories

Black-projects / mundane-tech hypothesis — cites as evidence
Crypto-physicalist / nuts-and-bolts hypothesis — cites as evidence

More — sighting wave