On December 21, 1998, at 2215 mountain standard time, a Boeing 727-233, N269FE, operated by Federal Express Corporation as flight 1004, was substantially damaged after being struck by a tug during push back at Denver International Airport, Denver, Colorado. The airline transport rated captain, first officer and flight engineer were not injured. The aircraft was being operated as a domestic cargo flight under Title 14 CFR Part 121, and visual meteorological conditions prevailed. An IFR flight plan was filed for the flight to Los Angeles International Airport, Los Angeles, California. According to a Federal Express Corporation representative, a tug was pushing the aircraft back from the gate when the wheels of the airplane got stuck in a snow bank. The tow bar shear pin, designed to break under excessive loads, snapped in half. The tug struck the airplane, breaking its windshield and causing damage to the aircraft's radome and forward pressure bulkhead. Denver International Airport operations personnel are responsible for the removal of snow. According to a ramp manager from the Federal Express Corporation, the snow bank in which the aircraft became mired was 12-16 inches from both the ramp and service road. He stated that the snow should have been plowed but not allowed to accrue in that location.