Aviation Accident Summaries

Aviation Accident Summary DEN05LA048

Gunnison, CO, USA

Aircraft #1

N16732

Boeing 737-724

Analysis

According to the captain, after landing on runway 06, they rolled out and turned off on A8 taxiway. While taxiing westbound to the gate, airport operations requested him to hold on the taxiway between A4 and A5, to give a Delta Air Lines pushback crew some room to move another airplane. After stopping, he set the brakes, and made a passenger announcement. Approximately 3 minutes later, the airplane was struck from the left rear by a snowplow. The force of the impact pushed the left main landing gear forward approximately 10 feet, turning the airplane to the right as it rotated about its right main landing gear. The captain stated that he shut down the engines, requested an assessment from the flight attendants, and told the first officer to call for fire equipment. He then surveyed the damage from the cockpit window and aft galley service door window. By that time, the snowplow had backed off to the east approximately 50 yards. The captain stated that the airport visibility was reported at 2 miles. However, he could see the Western State "W" on a hill, approximately 2.5 miles south of the airport. After an assessment of the damage and confirmation from the fire crew that it was safe, the airplane was towed to the ramp and the passengers were deplaned with the airstairs. The snow plow operator stated visibility was poor. He said he was unsure of where the airplane was. As he was plowing the taxiway "out of nowhere was the 737." The driver applied brakes, but it was too late. Following the accident, the airport made several changes to its operating procedures with respect to snowplow operations and radio communications with airport vehicles.

Factual Information

On January 8, 2005, at 1333 mountain standard time, a Boeing 737-724, N16732, operated by Continental Airlines Inc, as Continental Flight 1662, was substantially damaged when it was struck by a snowplow while it was stopped on the taxiway at Gunnison-Crested Butte Regional Airport (GUC), Gunnison, Colorado. Instrument meteorological conditions (IMC) prevailed at the time of the accident. The airline transport certificated captain, airline transport certificated first officer, 3 flight attendants, and 68 passengers on board the airplane, and the driver of the snowplow were not injured. A passenger riding in the snowplow received minor injuries. The scheduled domestic passenger flight was being conducted under the provisions of Title 14 CFR Part 121 on an instrument flight rules (IFR) flight plan. The flight originated at Houston, Texas, at 0938. According to the captain, they landed on runway 06 at 1325, and rolled out to turn off on A8 taxiway. While taxiing westbound to the gate, airport operations requested him to hold on the taxiway between A4 and A5, to give a Delta Air Lines pushback crew some room to move another airplane. After stopping, he set the brakes, and made a passenger announcement. Approximately 3 minutes later, the airplane was struck from the left rear by a snowplow. The force of the impact pushed the left main landing gear forward approximately 10 feet, turning the airplane to the right as it rotated about its right main landing gear. The captain stated that he shut down the engines, requested an assessment from the flight attendants, and told the first officer to call for fire equipment. He then surveyed the damage from the cockpit window and aft galley service door window. By that time, the snowplow had backed off to the east approximately 50 yards. He stated that airport visibility was reported at 2 miles. However, he could see the Western State "W" on a hill, approximately 2.5 miles south of the airport. After an assessment of the damage and confirmation from the fire crew that it was safe, the airplane was towed to the ramp and the passengers were deplaned with the airstairs. The snowplow driver stated that when they started plowing around 1200, it was snowing and the "visibility was poor." There were no airplanes landing due to the weather; however, there was a 737 circling and waiting for the weather to clear. While he waited for a 737 to land, he continued to clear the taxiway and turnouts. He stated that once the 737 landed, it pulled off on A-7 or A-8, but he wasn't sure due to the "poor visibility." The 737 then taxied to the ramp. He resumed plowing the runway and when he was finished, he went back to cleanup the taxiway. The taxiway had not been plowed recently and was covered with snow. The plow was "really throwing snow up in the windshield." The windshield wipers were doing a good job, but the consistency of the snow made it hard to see. As he continued down the taxiway, "out of no where was a 737." He applied the brakes, but it was too late and the snowplow slid into the airplane, striking its left main landing gear. The snowplow driver stated that the snowplow's right side window was broken out. The airplane's engine exhaust was choking both of them so he backed up the snowplow to a safe distance. After the crew of 737 shut down the airplane's engines, he examined the damage to the airplane and noted that there were no fuel leaks. According to the passenger in the snowplow, he stated that he had no idea how fast they were traveling when they struck the airplane, however; while plowing earlier, he asked the driver how fast they were going and the driver stated "45 miles per hour." According to a second witness, the snowplow was approaching the parked airplane at a speed of approximately 40 to 60 miles per hour. According to the airport manager, the snowplow was an Oshkosh H-series truck with a 22-foot wide plow. The snowplow driver was plowing the taxiway and did not realize that the airplane had stopped. The snowplow hit the left main landing gear assembly. The right end of the plow blade struck the underside of the airplane's fuselage, on the wing-to-fuselage fairing, approximately 3 feet aft of the trailing edge of the wing. The impact resulted in a 10-foot gash, running forward from the point of initial contact along the keel beam between the main landing gear wheel wells. At 1235, Denver Automated Flight Service Station (DEN AFSS) reported "…Gunnison has gone from thin loose snow all surfaces to an inch of loose snow all surfaces." At 1335, the reported weather conditions at Gunnison-Crested Butte Regional Airport (elevation 7,673 feet msl) was, wind, 000 degrees at 0 knots; visibility, 1.5 statute miles; sky condition, overcast at 001; temperature, minus 6 degrees C.; dew point, minus 8 degrees C.; altimeter setting, 230.03. The calculated density altitude was 6,885 feet msl. According to Gunnison Airport Operations, as a result of this accident, on January 28, 2005, several protocol changes were made to enhance snowplow operations and radio communications with airport vehicles.

Probable Cause and Findings

the snowplow driver's failure to see the airplane during plowing operations. Factors contributing to the accident were the snowplow driver's excessive speed and the snow.

 

Source: NTSB Aviation Accident Database

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