On the afternoon of January 8, 1981, at approximately 5:00 PM, 55-year-old engineer Renato Nicolaï was working in the garden of his home on the hill of Le Vieux Pavé above the village of Trans-en-Provence in the Var department of southeastern France when a whistling sound drew his attention to the sky. He watched an object approximately 2.5 metres in diameter, shaped like 'two plates turned upside down against each other,' descend vertically at a controlled rate onto a terraced plot approximately 50 metres from his house. The object remained on the ground for about forty seconds before ascending vertically with another brief whistle and departing to the northeast.
Nicolaï reported the incident to the Trans-en-Provence gendarmerie the following day. The French government's Groupe d'Études et d'Informations sur les Phénomènes Aérospatiaux Non-identifiés (GEPAN, later renamed GEIPAN) — a formal UFO investigation office established within the French space agency CNES — dispatched investigators within 48 hours. The investigation, led by GEPAN chief Jean-Jacques Velasco, found on the landing site a distinctive pattern of compacted soil and vegetation in two concentric circular impressions approximately 2.5 metres in diameter. Soil and plant samples from within the rings were transported to the CEN-Grenoble and the Institute of Experimental Vegetal Physiology at Toulouse under chain-of-custody conditions.
Laboratory analysis of the samples — released by GEIPAN in the 1983 scientific report 'Trans-en-Provence Case: Technical Note 16' — produced extraordinary findings. The soil had been subjected to pressure of 4-10 tonnes and heat of 300-600°C, far beyond what any terrestrial vehicle could have produced on the spot. The surrounding vegetation showed chlorophyll and carotenoid pigments reduced by 30-50% in a gradient pattern radiating from the landing site, consistent with severe electromagnetic or radiation exposure. The biological alterations were confirmed in repeated sampling over 24 months. The Trans-en-Provence case remains the single most physically-evidenced governmental UFO investigation in world history, and has been repeatedly cited by U.S. Department of Defense UAP researchers including Dr. Peter Sturrock as methodologically exemplary.