On December 18, 2007, about 1943 mountain standard time, a Cessna 310R, N5499J, landed on runway 25L at the Phoenix Sky Harbor International Airport, Phoenix, Arizona. Thereafter, while the commercial certificated pilot was taxiing toward the airplane operator's designated cargo loading area on the airport's south cargo apron, the airplane collided with a parked and unattended container cart. The airplane's left main landing gear was sheared off, the bottom of the wing was lacerated, and the wing's spar was deformed. The airplane was substantially damaged. Aero Charter & Transport, Inc., Albuquerque, New Mexico, operated the airplane during the air taxi cargo flight that was performed under 14 Code of Federal Regulations Part 135. Visual meteorological conditions prevailed during the nighttime flight, and a company flight plan was filed. The pilot was the sole occupant in the airplane, and he was not injured. The flight originated from Kingman, Arizona, about 1835. The National Transportation Safety Board investigator interviewed the accident pilot, airport police and operations personnel, and the operator's Director of Operations (DO) along with other company employees. In pertinent part, the pilot did not indicate experiencing any mechanical malfunction with the airplane, which included its steering system, brakes, or lights. The pilot stated that while proceeding on taxiway Hotel he observed a turboprop airplane, and once past that airplane (and after exiting the taxiway) he commenced a southbound turn into the south cargo ramp. Seconds thereafter, he observed a cart on the tarmac. The pilot stated he tried to avoid contact with the cart by applying full right rudder and brake. The pilot estimated his speed between 15 and 20 miles per hour. The police officer stated that he observed about 50 feet of tire tread skid marks leading up to the accident airplane's main landing gear wheels. The officer documented the accident location and skid marks, and photographs were taken by airport operations personnel. The accident site and location of the impacted cart on the tarmac south of the object free area (OFA) was ascertained to be about 65 feet south of the OFA's boundary marking (demarcation) line that separates movement from non-movement areas. It was also about 134 feet east of the north-south oriented taxi lane, which is located on the west side of the cargo apron. Phoenix airport management evaluated the factual evidence obtained during the accident investigation and opined that the accident carts were located in an authorized area of the tarmac, and their location was in conformance with existing airport policy. The airport operations officer stated that the pilot had not followed the marked taxiway lines between taxiway Hotel (where the airplane exited runway 25L) and the lead-in line to the south apron. He stated it appeared that after the pilot crossed taxiway Hotel he cut diagonally (in a southwesterly direction) toward the cargo area. While proceeding on this route the airplane was not following any of the painted taxi lines. The route that the pilot took was somewhat shorter than the route which followed the painted lines. The accident cart was one of several that had been parked in a line on the tarmac. The carts bore reflective markers on their sides. The DO reported that the pilot was familiar with the nighttime cargo operation, and the prescribed taxi route from the runway to the designated parking area where cargo was to be loaded and unloaded from the airplane. The pilot had taxied over this area numerous times during the preceding 3 months. The pilot had apparently cut the corner off the prescribed route and had not followed the marked taxiway lines. As a result of the accident the DO issued a change to the company's "General Operations Manual." The GOM was revised to include the following requirements for pilots in the handling of airplanes: "During taxi all company aircraft must be operated on the yellow taxi line and taxi speed not to exceed fast walking speed."