Groom Lake: Lazar sees disc at S-4
In March 1989, Robert Lazar claimed to observe a disc-shaped craft during his third visit to S-4 near Groom Lake, Nevada. He described nine distinct flying saucers, focusing on one nicknamed the 'sport model' with advanced propulsion using Element 115.

Background
Sighting and Context
Robert Lazar reported in March 1989 observing a classically shaped disc-like object on his third visit to the secret S-4 facility at Groom Lake in Nevada. The object stood on three legs in a hangar, measured about 10β12 metres across and 4.5 metres high, with a pewter-coloured surface.
Object Details
Lazar said he saw nine different flying discs in all, of varying shapes and sizes. His assignment concerned one particular model, which he called the 'sport model' and examined on his fourth visit. It had three levels, of which he was given access to the lower two. Beneath the craft he found three gravity amplifiers, which focused waves from a reactor on the middle level.
Technical Characteristics
On the middle level he found a control console and tiny seats, unsuitable for human pilots. Parts of the hull could become transparent like windows. The propulsion used element 115 (later moscovium), which underwent fission in the reactor and produced antimatter to obtain energy at full efficiency. This distorted the gravitational field, allowing invisibility and travel beyond the limits of light speed. Only 223 grams were said to suffice for long missions; the aliens were said to have supplied 227 kilograms. Lazar read over 100 documents on propulsion, technology, and grey aliens from the Zeta Reticuli system.
Demonstration and Evidence
On one occasion he saw the object lift off, manoeuvre sideways, and land. He had access to records and photographs of extraterrestrial bodies. His statements were corroborated by test flight schedules and witnesses.