On September 16, 2004, at 1413 central daylight time, a McDonnell-Douglas DC-9-82, N253AA, operated by American Airlines as flight 1374, encountered a flock of birds after takeoff from runway 4L (7,500 feet by 150 feet, concrete) at Chicago O'Hare International Airport (ORD), Chicago, Illinois. The domestic air carrier flight was conducted under 14 CFR Part 121 while on an instrument flight rules flight plan. Visual meteorological conditions prevailed at the time of the incident. No injuries were reported by the 5 crew members and 107 passengers. The flight departed ORD with an intended destination of Philadelphia International Airport (PHL), Philadelphia, Pennsylvania. The flight crew reported that the flight took off and turned to a heading of 090 degrees as assigned by air traffic control. Approximately 5 miles from the airport and passing through 3,000 feet mean sea level, the captain noticed a flock of birds in the aircraft's flight path. The first officer, who was the pilot flying, was unsuccessful in avoiding them. The first officer stated: "The flock separated and passed on both sides of the aircraft. We felt and heard the impact. The left engine immediately seized and a fire warning ensued." The crew reportedly completed the engine fire and before landing checklists and returned to ORD for an emergency landing. The flight landed without further incident on runway 32L (13,000 feet by 200 feet, concrete) at 1419. Responding units from the Chicago Fire Department reported that the fire was extinguished by the time they observed the aircraft on landing rollout. Engine fragments were recovered from the residential area located under the aircraft's flight path northeast of the airport. In addition, a dead bird located within the debris path was also recovered. It was identified as a double-crested cormorant. It was estimated to weigh about 5 pounds intact, with a wing span of 52 inches and a length of 32 inches. Examination of bird debris subsequently recovered from the engine confirmed that at least two birds had been ingested. A detailed examination of the left engine was conducted. The engine exhibited fire damage in the area of the fuel/oil cooler. The outboard side of the cowling was burned through. Portions of the compressor blades were eroded and missing. The fan case was circumferentially fractured. The fan module was rotated approximately 45-degrees during the event. The fuel line from the fuel/oil cooler was pulled loose. Federal Aviation Administration certification standard for the engine required that it be able to withstand the impact of one 4-pound bird.