Buzzing in Manche, France

This investigation was carried out by SEPRA to examine a strange and suspicious patch of burned earth in a meadow in Normandy. It was the local police unit that, unable to determine the origin and cause of this phenomenon, called on SEPRA, which went to the site quickly. On October 27, 1989, the owner of a field discovered in it a large area where the ground was completely scorched. The mark is irregular in shape and measures nearly 17 meters long by 4 meters at its widest part. At the level of the mark, there is no vegetation left, the earth is black, and the ground is spongy and sunken 10 to 15 cm compared to the average level of the meadow. A 20 kV high-voltage line runs along the plot about fifty meters from the mark. A witness (T2) reported to the gendarmerie the strange behavior of his dog during the night of October 25 to 26, 1989, around 2 a.m., and the presence of a wide beam of light above the field in question. Core samples taken from the area show that the earth is burned to a depth of 2 to 3 cm, and the gray color of the clays shows that the soil was heated to a high temperature. The soil samples taken from the suspect area have a strong smell of petroleum products. The analyses carried out confirm the presence of kerosene in the samples. These analysis results suggest the hypothesis of a release of kerosene by an aircraft flying at low altitude and low speed. This kerosene could have been ignited by passing through the high-voltage line. Indeed, during the investigation, strong crackling from the line was noticed at the junction of certain insulators. Sparks could have occurred and ignited the hydrocarbon cloud. This hypothesis is supported by a witness who observed a very large blue flame on the area, a color typical of hydrocarbon combustion. This case is classified B: ground mark left by a fire.