On December 18, 2010, at 1100 eastern standard time, a Boeing 737-700, registration number N913WN, operated by Southwest Airlines as flight 2592 to Fort Lauderdale, Florida, collided with a Boeing 737-300, registration number N650SW, operated by Southwest Airlines as flight 3944 to Tampa, Florida, during pushback from the gate at Philadelphia International Airport, Philadelphia, PA. The left wing and horizontal stabilizer of N913WN contacted the right winglet and horizontal stabilizer of N650SW. N650SW had been previously pushed back and awaiting taxi clearance at the time of the incident. The tug operator reported he looked away at an uninvolved airplane and when he looked back, the wing walker was signalling him to stop, but he was unable to stop prior to impact. N913WN was substantially damaged due to the impact to the wing spar. N650SW had minor damage. There were no injuries to the 10 total crew members, 215 total passengers, and 2 ground operations personnel.