In 1989, a man named Chris Gibson was working on an oil rig when he saw a KC-135 Stratotanker, two F-111 Aardvarks, and a triangle-shaped craft refueling. He did not know what it was. During 1991 in Southern California, there were a lot of sonic booms being heard. There was also a pulse coming out of the engine. The most recent sighting was in 2006.