By ANDREW CHAVEZ FORT WORTH — Flight officer Chris Birley is busy reading a video monitor dotted with black and white images and glowing white orbs inside the Police Department’s helicopter. At 10 p.m. on a recent weeknight, he’s on routine patrol on the city’s east side with pilot Sam Williams, checking out a warehouse district.It takes a little more than 20 minutes to fly from one end of the city to the other — longer if they’re flying against the wind.