On February 20, 2011, at 1924 central standard time, a Boeing 737-823, N945AN, that was being pushed back from its gate at the Dallas-Fort Worth International Airport, Southlake, Texas, struck a parked McDonnell Douglas DC-9-82(MD-82), N70504. The Boeing 737-823 sustained minor damaged, but the McDonnell Douglas DC-9-82 was substantially damaged. Both airplanes were registered to American Airlines, Inc. Visual meteorological conditions (VMC) prevailed at the time of the accident. The Boeing 737 was being operated under the provisions of 14 Code of Federal Regulations (CFR) Part 121. An instrument flight rules (IFR) flight plan had been filed for the cross-country flight. The captain, first officer, 4 cabin attendants, and 139 passengers on board the airplane were not injured. There were no occupants aboard the DC-9. The Boeing was destined for Palm Beach International Airport (PBI), Palm Beach, Florida. The Boeing 737-823 was a scheduled domestic passenger flight, operating as American Airlines flight 1808. According to American Airlines, the 737 was being pushed straight back from gate A26 when the tow bar separated from the nose gear. The airplane rolled backwards, severing the communications cord to the flight deck. The captain and first officer, who were in the process of starting the engines, were unaware that the airplane was rolling freely. The 737's right wing tip struck the nose of the DC-9 that was parked at pad N. All occupants were deplaned and transported to the terminal. The tractor driver told investigators that the tow bar was already attached to the aircraft when he arrived. He attached the other end of the tow bar to the tractor. The driver said that he checked the tow bar and ascertained that the bypass pin was in place and the tow bar wheels were fully retracted. Examination of the tow bar by AALA maintenance personnel revealed no mechanical failures or abnormalities.