The flight nurse said he was sitting directly behind the pilot in a forward facing seat, and was occupied with making notes on the medical records for the patient transport and did not pay much attention to the outside scenery until they were over Honey Lake. He noted that usually they crossed the lake about 500 feet above the surface, but this time they were much lower. He estimated that they had descended to within 20 to 50 feet of the lake surface, and as they flew further out over the water, they seemed to get lower and lower.  

He looked over the pilot's shoulder, and to the right, and noted how glassy smooth the water was. He stated that it was like a mirror and reflected the clouds and the sky perfectly, and was "kind of mesmerizing and disorienting" to see clouds both above and below. Just before they hit the water the pilot said on the intercom, "Boy, it's disorienting when the lake is this smooth." The nurse looked out the right side window at the distant shoreline and thought to himself that the flight seemed very low. The helicopter then hit the water. 

The flight nurse and paramedic medical crew members stated that there were no apparent mechanical malfunctions or failures with the helicopter prior to the collision with the lake surface. The pilot held certificates for commercial, airline transport, and flight instructor, with ratings for single and multiengine land airplanes and helicopters. His pilot certificate was endorsed with instrument ratings for airplanes and helicopters. According to the operator's records, the pilot had accumulated a total flight time of 9,900 hours; with 8,200 helicopter hours, and 600 hours in the accident model. The pilot was a retired Army aviator who had flown both fixed and rotorary wing aircraft while in the service. 

Review of Federal Aviation Administration (FAA) medical certification records disclosed that the pilot held a second-class medical, which was issued April 24, 2001, with the limitation that the pilot wear corrective lenses. The record sheet for the pilot's last FAA medical examination noted that his distant and intermediate vision was 20/15 in each eye and his near vision was 20/100 in each eye. According to the operator's accident report, the helicopter was maintained under a manufacturer's inspection program. The last reported 100-hour inspection occurred 16.8 hours prior to the accident. The helicopter had accrued a total flight time of 8,139 hours. 

The operator reported the weather as 30 miles visibility; temperature 46 degrees Fahrenheit; wind 110 degrees at 8 knots; altimeter 30.02 inHg; and sky condition 18,000 overcast. The closest aviation weather reporting station is the Reno, Nevada, airport. The observations near the time of the accident were reporting sky 15,000 feet scattered with visibilities greater than 10 miles. 

The wreckage was recovered from Honey Lake on March 27, 2002. The approximate 10-miles in diameter lake is a non-perennial body of water located about 11 miles east of the Susanville Airport at an elevation of about 4,100 msl. Search and rescue personnel reported that the wreckage was located about 2.5 miles from the east shore line and about 3.5 miles from the west shore. The lake is on a normal routing from the Washoe Medical Center to the Susanville airport. According to underwater search and rescue personnel, the pilot was located 85 feet forward of the helicopter wreckage. The pilot's seat was found underneath the helicopter. The search and rescue divers opined that the pilot broke the restraint system and went through the front of the helicopter canopy. 

Examination of the extensively fragmented helicopter disclosed that all control system torque and push/pull tubes, and their associated rod end fittings, were accounted for. Scoring and other rotational evidence was noted on all drive system components.  

On March 25, 2002, the acting Lassen County Medical Examiner performed an autopsy on the pilot. During the procedure samples were obtained for toxicological analysis by the FAA Civil Aeromedical Institute in Oklahoma City, Oklahoma. The results of the analyses were negative for carbon monoxide, cyanide, and ethanol. The drug scan was positive for Acetaminophen (Tylenol) at 10.546 (ug/ml, ug/g). 

A human performance study was accomplished by Safety Board personnel. The report includes interviews with the surviving two crew members, the operator, and family members, and is included in the docket for this accident. 

As part of the study, the human performance investigators reviewed the Safety Board accident records since May 1982, and found 33 accidents with glassy water cited as a factor. Nine of the accidents involved helicopters, and all cited the pilot's failure to maintain altitude as part of the causal chain. Commonly cited factors also included glassy water conditions, which resulted in a lack of visual cues for the correct perception of altitude.

The Eurocopter AS350 Ecureuil ("Squirrel") is a single-engined light helicopter originally manufactured by A?rospatiale (now part of Eurocopter Group). The AS350 is marketed in North America as the AStar. The AS355 Ecureuil 2 is a twin-engined variant, while the Eurocopter EC130 is a derivative of the AS350 airframe.

Development began in the early 1970s to replace the Alouette II, and the first flight took place on 27 June 1974. Despite the introduction of the EC130, production of the Eurocopter AS350 remains strong. Both single and twin-engine versions have been built under licensed by Helibras in Brazil. 

On May 14, 2005 a standard-configured Ecureuil AS350 B3 piloted by Eurocopter test pilot Didier Delsalle touched down on the top of Mt. Everest, at 8,850 meters (29,035 feet). This record has been confirmed by the F?d?ration A?ronautique Internationale.