I saw these as well- you forget how loud helicopters can be! To add to the point "realist" brought up, Fort Hunter Liggett and Camp Roberts are both in southern Monterey/Norther SLO counties. Hunter Liggett is an Army Reserve training camp, and Roberts is a California National Guard training camp. My thought when those chinooks went over town was that they were transporting troops from Moffett Field (a Reserve and NG post) to Liggett or Roberts. I know that sounds a little too simple an explanation for some, but sometimes the simplest explanations are the right ones.