Background
On April 15, 2008, at approximately 1815 mountain daylight time, an Air Tractor AT-602 single-engine air tanker, registration N602AA, was destroyed when it impacted terrain while maneuvering near Fort Carson, Colorado. The commercial pilot, the sole occupant, sustained fatal injuries. The aircraft was operated by the Department of Defense (DOD), Fort Carson, for public use firefighting missions and was registered to Aero-Applicators, Inc., Sterling, Colorado. Visual meteorological conditions prevailed, and a company flight plan had been filed. The flight originated from Mertens Airport (3CO2) in Sterling at 1639.
Flight History
A 9,800-acre wildfire, designated Training Area 25 (TA25), had ignited on the Fort Carson military reservation on April 14, 2008. A unified command with DOD, United States Forest Service (USFS), El Paso County, and the City of Colorado Springs coordinated fire suppression and rescue efforts. On April 15, two Aero-Applicators aircraft were ordered by DOD to support the wildfire. According to the pilot of the second aircraft, the accident pilot initially declined a request to support the Fort Carson fire due to high winds, but after a diversion to another fire, they were redirected to TA25. Upon arrival, the incident commander (IC) directed a drop at the head of the fire, but after a dry run, the pilot reported winds and turbulence too strong. The IC then requested a drop along an east-west road north of the fire adjacent to Highway 115. The pilot executed the drop east to west at approximately 50 feet above ground level. The second pilot observed the accident aircraft in a vertical descent, impacting terrain at a 45-degree nose-down angle. Winds were estimated at least 30 knots and gusting.
Witness Observations
El Paso County Sheriff's Office personnel observed the aircraft flying west after its drop, then pitching up nearly vertically before dipping its wings and crashing. Two pilot-rated witnesses near the accident site reported seeing the aircraft drop its load, pull up, and then nose over into a vertical descent, with no time for recovery.
Aircraft and Wreckage Information
The accident aircraft, a 2005-model Air Tractor AT-602 (serial number 602-1135), was a low-wing, conventional-gear airplane powered by a Pratt & Whitney Canada PT6A-65AG turboprop engine. The wreckage was located on a grass-covered hill adjacent to Highway 115 at an elevation of about 6,600 feet mean sea level. The right wing leading edge was crushed aft, and the left wing was partially separated. The fuselage was crushed and the hopper destroyed. The flaps were found in the full 30-degree extended position, contrary to the Airplane Flight Manual recommendation of 10 degrees for fire control operations.
Meteorological Conditions
At the time of the accident, Fort Carson Butts Army Airfield, approximately 5 miles northeast, reported winds from 220 degrees at 26 knots gusting to 33 knots. Earlier in the day, winds between 20 and 40 knots had been recorded, and helicopters were removed from the fire due to high wind activity. The USFS air-to-ground contact estimated winds from the southwest at approximately 35 knots.
Weight and Balance
Estimated takeoff weight of the aircraft was 13,170 pounds, exceeding the maximum gross weight of 12,500 pounds. The center of gravity was estimated at 24.08 inches, aft of the 24.0-inch limit. Just before the drop, weight was 12,437 pounds with a center of gravity of 23.61 inches (within limits). After the drop, weight was 7,438 pounds with a center of gravity of 28.63 inches (within the 29.5-inch limit).
Additional Information
Due to a local procurement arrangement, several levels of personnel typically involved in wildfire dispatch were not included. The USFS air-to-ground contact stated that had he known the aircraft was carrying water and foam instead of retardant, he would not have requested that drop zone. The accident was the pilot's first firefighting mission for Aero-Applicators, Inc.