The Belgium Wave: Triangles & Radar (1989-1991)

Few modern UAP episodes have left such a dense mix of testimony, military documentation, and technical debate as the Belgian wave of 1989–1991. In late 1989, across the Walloon region and around Brussels, reports began to describe large, low-flying triangular objects bearing three bright white lights, often with a pulsing red light at center, moving slowly, hovering, or accelerating with startling agility. The sighting stream crested on the night of 30–31 March 1990, when Belgian Air Force (BAF) F-16s were scrambled and multiple ground radars reported targets roughly over the Brussels–Namur axis. What followed is a case study in multi-sensor data meets human perception: a blend of gendarmerie (police) testimony, radar recordings, and public-facing military memos that still fuels inquiry. (cobeps.org)

The setting: a country on alert

From autumn 1989 through 1990, Belgium’s airspace was busy in every sense – commercial traffic through the Brussels TMA, NATO radar coverage from control/reporting centers, and a press that quickly elevated the “triangles” into nightly talk. Notably, the Belgian Air Force made an unusual choice for the era: it cooperated with Belgium’s civilian UAP organization (then SOBEPS, later COBEPS) and allowed public briefings on the March 1990 scramble while the events were still fresh. The official BAF context note also stated that various “usual suspects” could be ruled out: no B-2, F-117, AWACS, ultralights or RPVs were operating in the implicated airspace during the main events. (das-ufo-phaenomen.de)

A declassified U.S. Defense Department intelligence information report titled “Belgium and the UFO Issue” (IIR 6 807 0136 90) circulated inside NATO channels on 26 March 1990, acknowledging numerous Belgian reports, noting ongoing BAF investigation, and recording that Lt Gen Terrasson, then Belgium’s operational air commander, “categorically eliminated any possible BAF aircraft or engine test involvement.” The memo specifically references public and press attention (La Dernière Heure, Le Soir) and repeated televised interviews with Colonel (later Major General) Wilfried De Brouwer, BAF Chief of Operations. The U.S. report’s very existence confirms that Belgium’s events triggered multinational interest at the time. 

The wave also nudged policy. In 1993, the European Parliament’s published proceedings noted a resolution by MEP Elio Di Rupo to set up a European Observation Centre for “UFOs” under the Committee on Energy, Research and Technology. While no EU center ever materialized, the motion captures how the Belgian wave had broadened the conversation from newsroom to legislature. (European Parliament)

Multi-witness episodes before the F-16 chase

Eupen – 29 November 1989

The first major cluster ignited near Eupen, close to the German border, where multiple gendarmerie teams and civilians described a large triangular craft with powerful lights “lighting up the ground.” In later interviews, Eupen gendarmes Nicoll and Hubert Von Montigny described slow, low-altitude movement and intense illumination. Their accounts were among the earliest official police testimonies that SOBEPS aggregated. Belgian media have periodically revisited their statements on anniversaries of the wave. (RTL info – La Une de l’actualité)

A rolling wave – December 1989

COBEPS’s retrospective statistics show how reports surged in the last quarter of 1989: 205 notifications in November and 227 in December (444 total in Q4 1989), with 14 gendarmes documented for the Eupen sector alone by the end of November. While the intensity varied by region and day, the profile, triangular lights at low altitude, slow motion, minimal noise, repeated across Liège province and into the Brussels periphery.

COBEPS also stresses a crucial historiographic point: Belgium’s wave included many investigated cases (roughly two-thirds of notifications resulted in an investigation report), but photographic documentation was rare and generally poor, a frustration openly noted in their own publications. This scarcity would later haunt the debate, especially after the collapse of one “iconic” image (see §6). (cobeps.org)

The 30–31 March 1990 radar-visual night

If the wave had a centerpiece, this was it. The BAF’s full report on the events (authored by Major Lambrechts) outlines a minute-by-minute chronicle from the Glons CRC and Semmerzake TCC radars, the Beauvechain RAPCON, and fielded gendarmerie patrols. A condensed timeline:

• ~23:00 local (30 Mar): A Wavre-sector gendarme at Ramillies reports three unusual lights toward Thorembais-Gembloux. The lights appear at the vertices of a triangle, color-shifting (red/green/yellow). Glons CRC begins to see an unidentified contact north of Beauvechain at ~25 knots. A patrol including Captain Pinson arrives and confirms multiple lights, noting color cycling and that the lights differ from stars by intensity and behavior. Semmerzake TCC soon confirms a clear radar contact in the same area.
• ~00:05–00:54 (31 Mar): Two F-16A fighters (AL-17 and AL-23) scramble. Across nine attempted intercepts, the jets obtain three short radar locks. In the first lock (00:13), the target’s computed speed jumps from ~150 to ~970 knots, with altitude changes from 9,000 → 5,000 → 11,000 ft and then to “ground level,” breaking the lock. Ground controllers report the fighters over the target at the lock loss. Later locks show rapid accelerations (e.g., 100 → 600+ knots), then break. No visual contact is ever reported by the pilots.
• Ground witnesses in the Wavre/Jodoigne sector continue to report geometric light formations moving slowly, sometimes reconfiguring from triangle to square and back, with occasional “jerky” motions and bursts of increased intensity. Near 01:30, witnesses report the lights fade and separate in four directions.
• Meteorology: Visibility 8–15 km, clear sky, slight temperature inversions near ground and around 3,000 ft. The report explicitly rejects inversion layers as an explanation for the 10,000 ft radar returns that night. This will become a focal point in later re-analyses.

The BAF report’s conclusions are equally notable. It underscores:

1. for the first time in the wave, there was positive radar confirmation (multiple sensors including F-16 fire-control radar) correlated with simultaneous ground observations,
2. ground witnesses included on-duty gendarmes, whose objectivity the BAF judged strong,
3. target kinematics logged during lock-ons appeared incompatible with conventional aircraft performance,
4. no sonic boom was reported despite measured speeds exceeding Mach 1, and
5. an array of conventional hypotheses was explicitly excluded (balloons, illusions, meteorological phenomena, holograms).

This official posture, cautious but firm that something genuine and unusual occurred, has made March 1990 one of the canonical military UAP cases in Europe. (das-ufo-phaenomen.de)

What the radars can and cannot tell us

Even strong radar cases invite physics and instrumentation scrutiny, and Belgium’s was no exception. Three broad layers of analysis emerged:

The Air Force & “data say it’s not ours”

The Lambrechts report (above) captured operational facts in near real-time and assessed them against known systems. In parallel, and less public at the time, the BAF’s Electronic Warfare Center (EWC) performed a deeper technical study of the F-16 radar tapes. A widely circulated briefing document compiled by CUFOS/FUFOR/MUFON in 1995 (with cooperation from Belgian officials) summarized that the EWC analysis, led by Col. Salmon and physicist M. Gilmard and subsequently reviewed by Prof. Auguste Meessen (UCLouvain), found aspects remaining unexplained even after attempting prosaic accounting. (The document reproduces F-16 radar trajectories and discusses the lock events.) (Internet Archive)

A separate U.S. Defense Department memo already cited (§1) recorded Belgium’s own top brass affirming no Belgian aircraft or engine tests could account for the primary sightings, an important boundary condition when speculating. 

Atmospheric/propagation artifacts hypothesis

Critics counter that at least some of the apparent high-speed jumps and “disappearing underground” tracks are classic artifacts of look-down fire-control radar operating near ground clutter under certain atmospheric conditions. A commonly invoked mechanism is Bragg scattering, coherent backscatter from quasi-periodic refractive structures that can produce spurious or unstable returns and the “angels” familiar in air-surveillance lore. While Bragg scattering is best documented at HF/VHF coastal radars, its underlying physics applies broadly; it remains a standard entry in radar-engineering references. Skeptical treatments of the Belgian tapes have argued that the short-duration F-16 locks were exactly the sort of track-while-scan/auto-track anomalies that can be induced by clutter + propagation quirks rather than hard targets. (radartutorial.eu)

Hybrid takes from Belgian investigators

COBEPS’s long retrospective on the wave concedes the heated debate around March 1990 and documents a shift, even among some wave chroniclers, toward hybrid interpretations: rare atmospheric phenomena and radar calibration issues might explain elements of the F-16 data, while the ground observations still point to structured lights behaving in unusual ways at low altitude. In other words, what the fire-control radar did (or didn’t) see does not trivially negate the independent visual/radar picture from other sensors and witnesses. (cobeps.org)

Bottom line: the March 30–31 data set is internally complex. The BAF stands by the night’s genuine unknowns; skeptics stand by propagation artifacts. The debate has endured because both sides can selectively point to features that favor their view: lock-on kinematics and multi-sensor correlation for one, fragile lock persistence and known radar pathologies for the other. (das-ufo-phaenomen.de)

The air-traffic & command-and-control context

Understanding March 1990 also means understanding where it took place in the system. The tracks ran through Brussels TMA and the Beauvechain sector, with CRC Glons and TCC Semmerzake both reporting contacts, and RAPCON Beauvechain adding confirmation at times. The BAF’s own chronology shows nine fighter intercept attempts; three transient locks; frequent handoffs between military and civilian ATC (VHF/UHF coordination); and a spatial pattern where ground clusters of lights were reported broadly coincident with the radar activity region. That is exactly the kind of mixed civil-military radar picture that makes definitive post-hoc reconstruction so hard – and why the BAF documented it so carefully. (das-ufo-phaenomen.de)

Photographs, the Petit-Rechain collapse, and the burden of proof

For decades, one image symbolized Belgium’s triangles: the Petit-Rechain photograph, published widely in April 1990 and showing a black triangular silhouette with three bright corner lights and a central glow. In July 2011, the photographer Patrick Maréchal went on Belgian TV (RTL) and admitted it was a hoax -a painted polystyrene model with embedded lights, suspended and photographed. International agencies quickly picked up the story; Reuters coverage remains the best single citation. The hoax admission did not retroactively disprove the wave, but it did remove the most “photogenic” exhibit from the evidentiary table and underscored COBEPS’s earlier lament: high-quality, close-range imagery was essentially absent from the wave. (Reuters)

Press coverage and memory

The Belgian and international press played a large role. The U.S. IIR memo (March 1990) explicitly cites La Dernière Heure and Le Soir coverage and notes repeated TV interviews with BAF officials; BBC and other European outlets carried segments through 1990, and the case still recycles in anniversary features. This sustained visibility likely amplified reporting (healthy and unhealthy), which in turn complicated later statistical inference about “how many saw what.” But it also ensured that operational documents, radar timelines, scramble orders, were preserved and disseminated unusually widely for a live case. 

What is known, and what remains contested

Known with documentation:

• Multi-sensor returns were recorded on 30–31 March 1990: ground radars (Glons CRC, Semmerzake TCC, Beauvechain RAPCON) and F-16 radar tapes, with a detailed official chronology issued by the Belgian Air Force within weeks. No visual acquisition by pilots; multiple gendarmerie and civilian visuals on the ground. (das-ufo-phaenomen.de)
• BAF publicly excluded stealth test flights, AWACS presence, balloons, or holographic projections and emphasized that reported kinematics during locks were not compatible with known aircraft, while also acknowledging the sonic-boom paradox (speeds over Mach but no boom reported). (das-ufo-phaenomen.de)
• A U.S. DoD memo contemporaneous to the wave documented that Belgian commanders eliminated BAF test involvement; NATO-side interest was real. 
• The Petit-Rechain photo was a confessed hoax (2011). (Reuters)

Contested and debated:

• Whether the F-16 locks represent coherent targets performing extreme accelerations, or artifact tracks riding radar clutter/propagation oddities (e.g., Bragg-type or “angel” phenomena) plus tracking-logic quirks. (Internet Archive)
• The degree to which ground reports on 30–31 March correlate with the radar tracks (perfectly? loosely? not at all?). Officially, the BAF saw correlation sufficient to scramble and publish; skeptics claim asynchrony and post-hoc clustering. (das-ufo-phaenomen.de)
• How to weigh late-arriving testimonies (common in waves) versus near-time logs; COBEPS’s own statistics show both robust early signals and later media-driven “contagion.” (cobeps.org)

Synopsis 

A sober reading of the Belgian wave is neither “all misidentifications” nor “one smoking-gun craft.” The record points to several layers:

1. A real social-technical event unfolded from late 1989: many independent witnesses, including on-duty police, repeatedly reported structured light formations at low altitude over populated areas. These reports cluster in time and place beyond random “noise” and were substantial enough for the Air Force to engage repeatedly. (cobeps.org)
2. On 30–31 March 1990, multi-sensor data exist and were officially published by the BAF. Whatever the perfect reconciliation of radar physics with eyewitness perception, this alone places the night in a higher evidentiary tier among modern UAP cases. (das-ufo-phaenomen.de)
3. Radar ambiguity is real. Fire-control radars can generate persuasive illusions under the wrong conditions, and Bragg/angel phenomena are not folklore but physics. Yet ambiguity is not refutation: the BAF itself assessed the data as incompatible with conventional aircraft and ruled out easy meteorological or man-made explanations for that night’s ensemble. The contention therefore isn’t “nothing happened,” but what happened – and whether some subset of the reports still indicates non-prosaic aerial activity. (radartutorial.eu)
4. Imaging failed the case. Aside from a few ambiguous long-distance shots, the wave produced no definitive imagery, and its most famous photo proved fabricated. That removes one line of evidence but doesn’t erase the rest. (Reuters)

Why the Belgium wave still matters

The wave set several benchmarks that still shape government and scientific approaches to UAP:

• Transparency: The BAF’s willingness to publish a chronology with technical qualifiers (e.g., speeds, altitudes, lack of sonic booms) created a durable primary record, rare for a live case. (das-ufo-phaenomen.de)
• Civil-military collaboration: SOBEPS/COBEPS and the BAF shared data and fieldwork, a model later emulated in other countries’ projects. (das-ufo-phaenomen.de)
• Policy ripple: The European Parliament briefly considered UAP observation at the EU level, an early acknowledgment that air-safety and scientific issues can intersect. (European Parliament)
• Methodological caution: Belgium demonstrates how radar data can be both vital and ambiguous; how iconic images can mislead; and why multi-sensor, time-synced collection (including spectroscopy/IR today) is crucial.

For UAP historians and analysts, Belgium remains a reference case: strong official documentation, sincere attempts at explanation on both sides, and a residual that keeps the door open to genuinely novel aerial phenomena.

References

1. Belgian Air Force – Report concerning the observation of UFOs in the night from March 30 to March 31, 1990 (Full Report) (Major Lambrechts). (English translation; chronologies, radar/visual summaries, conclusions). (das-ufo-phaenomen.de)
2. U.S. DoD (declassified) – IIR 6 807 0136 90: Belgium and the UFO Issue (26 Mar 1990). Notes press environment; records that Belgian commanders ruled out BAF test involvement; summarizes witness/press items. 
3. COBEPS – Belgian Ufology: What future developments are to be expected after the Petit-Rechain fiasco? (40-pp. retrospective; statistics; radar debates; photography analysis). (cobeps.org)
4. Reuters – Belgium UFO photo was a hoax: originator confesses (2011). Confirms Petit-Rechain was staged with a polystyrene model. (Reuters)
5. CUFOS/FUFOR/MUFON – Unidentified Flying Objects: Briefing Document, The Best Available Evidence (1995). Summarizes Belgian wave; references EWC (Air Force) technical study of F-16 tapes (Col. Salmon; M. Gilmard) and Prof. Auguste Meessen review. (Internet Archive)
6. European Parliament – Published proceedings noting Elio Di Rupo’s resolution B3-1990/90 to establish a European Observation Centre for “UFOs” (1993; official EU PDF compilation). (European Parliament)
7. Radartutorial – Technical explainer on Bragg scattering and radar “angels,” frequently cited in skeptical interpretations of the Belgian F-16 tracks. (Physics/mechanisms overview.) (radartutorial.eu)
8. Belgian media retrospective – RTL Belgique interviews/coverage of Eupen gendarmes and 30-year look-back (2019). (RTL info – La Une de l’actualité)

Claims Taxonomy

Verified

• Existence of BAF multi-sensor chronology and scramble (F-16 attempts, radar timelines); correlations noted by BAF between radar and ground reports on 30–31 March 1990. (Primary source: BAF report.) (das-ufo-phaenomen.de)
• U.S. DoD IIR memo “Belgium and the UFO Issue” documenting official attention and ruling out BAF test involvement. 
• Petit-Rechain hoax admission (2011). (Reuters)

Probable

• The late-1989 Eupen cluster contained multiple independent, near-time witness reports by trained observers (gendarmes) describing a large triangular craft at low altitude with intense lights. The pattern is consistent with other reports in the region that quarter. (Press retrospectives and COBEPS statistics.) (RTL info – La Une de l’actualité)

Disputed

• Interpretation of F-16 lock data: unknown craft executing extreme accelerations (BAF & some researchers) vs. radar artifacts from propagation/clutter and tracking-logic quirks (skeptical analyses). (das-ufo-phaenomen.de)
• The extent and strength of radar–visual correlation on the night of 30–31 March. (das-ufo-phaenomen.de)

Legend

• Not applicable.

Misidentification

• Petit-Rechain photograph, deliberate hoax; not evidentiary for the wave. (Reuters)

Speculation Labels 

Hypothesis (physics/measurement): Some of the March 30–31 F-16 “jumps” and lock breaks could represent track-while-scan instabilities over ground clutter enhanced by atmospheric refractive layers (e.g., Bragg-type scattering), producing target solutions that mimic extreme acceleration. This could coexist with a real luminous stimulus observed from the ground, the radar and visual “targets” need not be the same object. (radartutorial.eu)

Witness Interpretation: Repeated reports of silent, slow-moving triangular lights at low altitude were widely taken to indicate single large platforms. Some witnesses also reported reconfiguration (triangle → square) and jerky “step” motions; if accurate, these patterns challenge simple aircraft explanations (e.g., solitary helicopter), though multiple helicopters/aircraft in loose formation remains a competing interpretation in a minority of cases. (cobeps.org)

Researcher Opinion: Given the BAF’s own exclusions, the multi-sensor character of 30–31 March 1990, and the years-long reporting profile, Belgium’s wave likely includes more than a single prosaic class of stimuli. A layered model, rare atmospheric/propagation effects + scattered conventional traffic + a residual of novel aerial phenomena, best fits the record. The residual is where sustained, instrument-forward fieldwork would still have the most epistemic leverage.

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