By Dale DenwaltStaff writer ddenwalt@oklahoman.comOn a cool April night last year, police helicopter pilot Sgt. Tim Campbell cruised over Oklahoma City about 1,000 feet above the ground. At the same time, someone else pushed their unmanned drone to the same altitude, which is more than twice the 400-foot limit allowed by federal regulations. Somewhere over SE 29 Street in Oklahoma City, Campbell's tactical flight officer spotted the drone and its green light shining through the darkness.Read more on NewsOK.com