Elko, NV, USA
N7077N
WSK PZL Mielec M-18A
The airplane impacted terrain when it encountered tailwind and downdraft conditions during a fire retardant delivery flight over a ridgeline. According to the pilot, he flew the airplane over the drop site between 95 and 100 miles per hour (mph), about 60 feet above the terrain, and with 30 degrees of flaps extended. After dropping the retardant, he applied full power and retracted the flaps to 10 degrees with normal engine indications. The airplane would not climb without losing airspeed and the pilot realized he would not be able to clear the ridgeline in his flight path. He slowed the airplane as much as possible before the airplane collided with terrain. The weather observation at a nearby airport and reports from ground personnel close to the site indicated high and gusty wind conditions with velocities as high as 40 knots existed at the time of the accident, and would have resulted in a tailwind condition for the airplane as it made the retardant drop.
On August 23, 2005, at 1412 Pacific daylight time, a WSK PZL Mielec M-18A airplane, N7077N (call sign Tanker 426), impacted terrain while maneuvering through a fire retardant drop 12 miles north of Elko, Nevada. The Bureau of Land Management (BLM) was operating the aircraft as a public-use firefighting tool under the provisions of 14 CFR Part 91. The commercial pilot, who was the sole occupant, sustained minor injuries. The airplane was substantially damaged. Visual meteorological conditions prevailed and a company flight plan was filed. The local flight departed the Elko Regional Airport at 1403, and was dropping retardant on the Sherman Fire when the accident occurred. According to the BLM personnel, the pilot reported dropping a fire retardant load (approximately 500 gallons or 4,035 pounds) downhill in a downwind condition. He dropped the fire retardant at an indicated airspeed between 95 and 100 miles per hour (mph), about 60 feet above the ground, with 30 degrees of flaps extended. After dropping the load, the pilot applied full power, raised flaps to 10 degrees (incrementally), and attempted to climb. According to the pilot, the airplane was incapable of climbing without losing airspeed; however, the engine was producing full power and there were no noted anomalies with the airplane or engine. When the pilot realized he would be unable to clear the ridgeline in front of him, he maintained a wings level attitude and slowed the airplane as much as possible before colliding with terrain. The airplane impacted the ground at the 7,044-foot level of the 7,090-foot ridge, resulting in the separation of the landing gear, and substantial damage to the wings and flight control surfaces. The pilot was picked up by a ground vehicle and transported to a hospital with minor injuries. According to the pilot's written statement, the flight was uneventful until reaching the ridgeline near the fire. When the airplane crossed the top of the ridgeline it "encountered turbulence and a down draft." The pilot completed the drop and added power to full throttle and retracted flaps to 10 degrees with an airspeed of 110 mph. The pilot reported that all engine indications were normal and there were no anomalies noted with either the airplane or engine. The pilot continued to raise the nose to arrest the descent rate and slowed the airplane to 95 mph, but the airplane continued to lose altitude. He then realized the airplane would be unable to clear the next ridgeline and elected to maintain full power while pitching up and slowing the airspeed as much as possible. When the airplane was 20 feet above the ground, the pilot maintained a nose high pitch attitude until the airplane stalled and contacted the ground with little forward speed. He secured the airplane and exited the aircraft. The pilot reported the wind from the west-southwest at 20 knots with gusts to 40 knots at the time of the accident. At 1456, the Elko Regional Airport's weather observation facility (field elevation of 5,140 feet mean sea level) reported the wind from 260 degrees at 19 knots with gusts to 25 knots. BLM personnel indicated that ground units near the accident site were reporting winds up to 30 knots. The pilot reported accumulating a total of 13,460 flight hours, of which 550 hours were accrued in the same make and model as the accident airplane. When asked what could be done to prevent a similar accident from occurring, the pilot suggested the following: 1) Once it is determined that gusty wind conditions exist, tanker pilots should conduct at least one dry pass at a minimum of 100 feet above the ground before making retardant delivery pass. 2) If a lead airplane experiences turbulence or gusty wind conditions they should report the information to dispatch as soon as possible for dissemination to the other air crews. 3) Downwind retardant deliveries over a ridgeline should be avoided in all cases when winds are reported to be over 25 mph. 4) Pilots should never rely on power alone to get out of a downdraft situation.
the pilot's failure to adequately plan for the wind direction and speed during a fire retardant delivery flight, which led to a loss of true airspeed, failure to attain a proper climb rate, and the in-flight collision with mountainous terrain. Contributing factors were the high, gusty, tailwind conditions.
Source: NTSB Aviation Accident Database
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