Aviation Accident Summaries

Aviation Accident Summary LAX04LA281

Little Valley, CA, USA

Aircraft #1

N549W

Bell 206B

Analysis

The helicopter collided with trees and terrain while the pilot maneuvered at a low altitude, under high density altitude conditions, and over rising mountainous terrain. The purpose of the aerial survey flight was to provide a California Department of Forestry passenger with an aerial mapping opportunity around active fire areas in the Lassen National Park. The pilot indicated that his specific mission on the flight was to maneuver the helicopter over a route that would provide the front seat passenger an opportunity to accurately mark global positioning satellite (GPS) waypoints around the fire area. Initially, the pilot flew at 6,500 feet mean sea level (msl), but when the passenger started marking waypoints, the pilot descended to 5,500 feet msl. The pilot further indicated that during the flight he made several turns. Just prior to the crash, he flew in a southerly, and then a northerly direction. When he next turned, to an east-southeasterly direction, he raised the collective, observed his proximity to the fire line, and directed his attention to a hill that he was approaching. The pilot indicated that he had expected to be higher than the top of the hill, but he was lower. At this time, despite his efforts to increase altitude, the helicopter impacted trees and terrain. According to ground-based witnesses, the helicopter had been maneuvering between 50 and 75 feet above ground level, in a downwind direction, over 5,100-foot mean sea level upsloping terrain, toward the crest of the mountain. The surface wind was from the north-northeast, about 10 knots. The temperature was almost 90 degrees Fahrenheit. The witnesses further reported that the helicopter's engine was operating until it impacted trees, about 20 feet beneath the mountain crest.

Factual Information

On July 26, 2004, about 1421 Pacific daylight time, a Bell 206B, N549W, collided with trees and terrain while maneuvering about 4.9 nautical miles southeast of Little Valley, California. The helicopter was operated by Aris Helicopter, Ltd., Moffett Field, California. Visual meteorological conditions prevailed during the aerial survey flight for the California Department of Forestry (CDF), and a company flight plan was filed. The helicopter was substantially damaged during the impact sequence and was subsequently destroyed in the post impact forest fire. The commercial pilot and one passenger were seriously injured; the second passenger sustained minor injuries. The flight was performed under the provisions of 14 CFR Part 91, and it originated from Fall River Mills, California, about 1402. According to the CDF Aviation Safety Officer who responded to the accident site, the purpose of the flight was to provide the two CDF passengers with an aerial mapping opportunity around active fire areas in the Lassen National Park. Ground-based witnesses observed the helicopter flying between 50 and 75 feet above ground level, in a downwind direction, over the 5,100-foot mean sea level (msl) upsloping terrain. The surface wind was from the north-northeast, about 10 knots. The helicopter was flying on a southwesterly course, toward the crest of a mountain. The temperature was almost 90 degrees Fahrenheit. The witnesses further reported that the helicopter's engine was operating until it impacted trees, about 20 feet beneath the mountain crest. The pilot indicated that his specific mission on the accident flight was to maneuver the helicopter over a route that would provide the front seat passenger the opportunity to accurately mark global positioning satellite (GPS) waypoints around the perimeter of the fire area. Initially, the pilot flew at 6,500 feet msl, but when the passenger started marking waypoints, the pilot descended to 5,500 feet msl. The pilot further indicated that during the flight he made several turns. Just prior to the crash, he flew in a southerly and then a northerly direction. The pilot reported that when he turned to an east-southeasterly direction, he "pulled in as much collective as [he] could...," and he observed his proximity to the fire line. Thereafter, he directed his attention to a hill that he was approaching. The pilot indicated that he had expected to be higher than the top of the hill, but he was lower. At this time, despite his efforts to increase altitude, the helicopter impacted trees and terrain.

Probable Cause and Findings

the pilot's failure to maintain an adequate clearance from objects and terrain while maneuvering at low altitude. Factors in the accident were the high, rising terrain, and the high density altitude.

 

Source: NTSB Aviation Accident Database

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