Twin Commander 690B, Rio Grande, P.R., Dec. 3, 2008–The Webstas Aviation Services Aero Commander was destroyed when it crashed in the mountains while maneuvering about four nm southeast of Rio Grande, killing the ATP-rated pilot and two passengers. The controller saw that the airplane, headed for Luis Munoz Marin International Airport, San Juan, was deviating from its assigned heading, taking it toward mountainous terrain, and asked the pilot about his altitude. The pilot said he was descending to 3,200 feet and the controller told him that the minimum vectoring altitude was 5,500. The pilot said he was in and out of some clouds and was told to maintain VFR. Witnesses reported fog and rain and mountain obscuration in the area.