One strange thing I noticed during my time in San Francisco was how many helicopters seemed to be in the sky at any given time. While I went through the Presidio there was one Sheriff's department chopper that I could've sworn was following me at first - presumably because I lack the implants common in Americans that are used to determine how many licks it takes to get to the center of a Tootsie Roll - but it turned out to just be doing really wide circles over the area. There was also what I believe to be a UH-60 Black Hawk doing a few passes over the Golden Gate - whether it was a training flight, a patrol, or something else entirely, I have no idea.
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