VIDEO: The engine rumbled to life. A propeller spun with a rush of noise, and Mike Callahan gently guided his small single-engine plane, a Cessna Skywagon 185, toward a runway at Wittman Regional Airport in Oshkosh. He checked his instruments a final time on the plane's faded yellow dashboard and radioed the control tower. He was ready to fly. A few moments later, Callahan was hundreds of feet above the shores of Lake Winnebago. He soared above treetops and rain-soaked farm fields. He pointed out a bald eagle perched on a branch far below.