Mattydale, N.Y. — Two commuter airplanes came so close to each other near Syracuse Hancock International Airport this week that one pilot took evasive action and a mid-air collision warning sounded. The automated alarm in the cockpit of American Flight 5511 warned that another plane, Delta Flight 5421, was getting very close, according to audio recordings of radio traffic. The alarm typically rings about 20 seconds before a potential collision. Air traffic controllers had directed the American flight to pull up quickly from its landing because they had cleared the Delta flight to take off on t…