Southwest Airlines flight 2217 struck a bird while climbing though 6,000 ft. after departure from the St. Louis Lambert International Airport (STL), St. Louis, Missouri. According to the flight crew, during the climb they saw a ?quick flash’ pass diagonally from right to left across the nose of the airplane, followed by a ?thud’ sound. Which they surmised was a bird that had impacted the nose or belly area of the airplane. After confirming that the flight controls, engines, and pressurization system were operating normally, they decided to continue to their destination. They advised the company of a possible bird strike via an aircraft communicating and reporting system (ACARS) message to coordinate with maintenance for an inspection and damage assessment upon landing. The flight continued normally with no change in the performance or operation of the airplane and landed without further incident. After landing the crew performed a post-flight walk around to search for any evidence of a bird strike, when they discovered impact damage to the leading edge of the left horizontal stabilizer. Maintenance personnel subsequently discovered a crack, about 12 inches long, in the left horizonal stabilizer lower spar chord. Although the bird impact caused substantial damage to the left horizontal stabilizer, the flight crew was able to control the airplane and the captain reported that ?the flight controls and everything felt normal’. Probable Cause: A bird strike during climbout.