Introduction
On an unspecified date, a helicopter operated by the United States Department of Agriculture (USDA) was transporting firefighters to a wildfire. The aircraft was conducting an approach to a pinnacle located on a ridge line at 9,520 feet above mean sea level (MSL). Two survivors provided statements regarding the sequence of events.
Approach and Accident Sequence
According to the survivors, the pilot executed a downwind approach to the intended landing area. During the final phase, the pilot attempted to bring the helicopter into a hover approximately 20 feet above the ground. Witnesses observed that the nose of the helicopter appeared higher than normal during this phase. Subsequently, the helicopter assumed a very high nose attitude and seemed to begin sliding backwards. This was followed by a loss of control, and the helicopter made contact with trees.
Conditions
At the time of the accident, the density altitude was calculated to be 13,200 feet. The aircraft weight was determined to be 3,750 pounds. Under the prevailing conditions—no wind, pressure altitude of 9,520 feet, and temperature of 32 degrees Celsius—the maximum gross weight for a hover in ground effect was computed to be 3,580 pounds, and for a hover out of ground effect, 3,515 pounds. The impact of these conditions on the accident sequence is not explicitly stated in the available information.