An evacuation slide inflated inside a United Airlines plane as it flew from Chicago to California, filling part of the cabin and forcing the pilot to make an emergency landing in Kansas, the airline and passengers said. Mike Schroeder said he was flying to Orange County, California, late Sunday when he heard a hiss and pop. Schroeder said he turned around and saw the plane's evacuation slide — which would normally go outside the plane during an emergency — inflating inside the cabin.