On May 28, 1999, about 1510 eastern daylight time, a Boeing 727, N282SC, operated by Sun Country Airlines, as flight 744, was substantially damaged when it's left wing struck a catering truck during pushback at the Washington Dulles International Airport, Sterling, Virginia. The 3 flight crew members, 4 flight attendants, and 83 passengers were not injured. The two occupants of the catering truck were also not injured. Visual meteorological conditions prevailed and an instrument flight rules flight plan had been filed for the flight destined for the Minneapolis-St.Paul International Airport, Minneapolis, Minnesota. The scheduled passenger flight was conducted under 14 CFR Part 121. The airplane was parked on gate C-24, and was being pushed back by a United Airlines, Aviation Maintenance Technician. The pushback was conducted as a "one person pushback." In a written statement, the tug operator said he waited for an Airbus 320, to taxi to gate 26, and then began to pushback the airplane for a "west taxi." He also stated that the airplane's rotating beacon was "ON." The tug operator further stated: "...There were no ground equipment on my left. All the service tugs were to my right. I was particularly concerned about the fueling truck to my right. I cleared all and was now about 125 to 150 feet into my push. Since he was going for a west taxi I started to turn the nose wheel and I know I was on the right side of the aircraft. By now my main wheels were approaching the edge of the service road, which in my experience is a sign that I was clear to taxi way. I engaged the food truck and my tow bar sheared and I stopped." In a written statement, the catering truck operator said he had stopped the truck behind the left wing of the 727, while he waited for the Airbus to shut down it's engines. "My partner ...yelled, 'He's moving or something' and instantly I tried to accelerate, but at the same time we were struck on the side and we were turning over..." Ramp personnel in the area observed the airplane heading towards the parked catering truck, and attempted to alert the tug operator before the collision. According to a Federal Aviation Administration Inspector, the airplane's left wing struck the aft section of the catering truck. The catering truck then flipped over onto it's side. The airplane's left aileron and left wing tip were damaged. According to airport personnel, the distance from the airplane's left wingtip when parked at the gate, to the north edge of the service road where the catering truck was parked, was about 75 feet. Subsequent to the accident, United Airlines revised the "One Person Pushback" procedures for the Boeing 727 and 737 aircraft to include a "guide person." The responsibilities of the guide person included signaling the tug operator that the ramp is clear, and maintaining verbal or visual contact with the tug operator until the aircraft clears the gate envelope.