At about 16:30 in the afternoon of 19 July 1952, the attention of Customs Inspector, Sr. Domingo Troncoso, then with the Peruvian Customs Office at Puerto Maldonado on the jungle frontier with Bolivia, was called to a very strange cigar-shaped flying object over the river area.

The big dirigible-shaped craft was flying horizontally and fairly low in the sky, passing from right to left from the observer's position. It was leaving a dense trail of thick smoke, vapor, or substance of some kind on its wake. The thick, whitish substance appeared to be emitted from the aft end of the object in flight.

That this object was a real, structured, physical machine may be seen from its reflection in the waters of the Madre de Dios River underneath it. It can be clearly seen to be well above the broad-leaved jungle trees along the bank of the river in the foreground of the picture.

The object was estimated to be over a hundred feet long. Sr. Troncoso obtained a camera and was able to get one good photograph of the cigar-shaped object.

The trail persisted for about 15 minutes.When the trail settled to the ground it turned out to be a mass of thin fibrous threads. A Peruvian newspaper reported that the color of the head or nucleus of this disc was an intense orange. Based on sightings about 120 km (73 miles) and about 4 minutes apart, its speed was computed at around 1100 mph. The object, which was flying at low altitude and emitting a buzzing sound, also reportedly knocked out radio communications, indicating that it was causing intense electromagnetic interference.