The commuter plane that crashed near Buffalo was on autopilot until just before it went down in icy weather, indicating that the pilot may have ignored federal safety recommendations and violated the airline's own policy for flying in such conditions, an investigator said Sunday. Federal guidelines and the airline's own instructions suggest a pilot should not engage the autopilot when flying through ice. If the ice is severe, the company that operated Continental Flight 3407 requires pilots to shut off the autopilot.