Aviation Accident Summaries

Aviation Accident Summary WPR15LA193

Salinas, CA, USA

Aircraft #1

N4427F

BELL 47G 5

Analysis

The non-instrument-rated pilot was conducting aerial application flights in the helicopter and had completed several work orders at various locations before the accident flight. Two coworkers refilled the fertilizer tank on the helicopter and saw it depart from the loading area. About the time that the helicopter was expected to return, a thick fog came in, and the visibility dropped to about 15 to 20 ft. When the helicopter did not return, one of the coworkers searched for the helicopter and found the accident site. Examination of the wreckage did not reveal evidence of any pre-impact mechanical failures. It is likely that the pilot lost visual contact with the ground due to the fog and subsequently experienced spatial disorientation and lost control of the helicopter. This pilot had a similar accident in the helicopter about 5 years earlier, which suggests that he had a habit of taking risks with the weather. Toxicology testing of the pilot was positive for hydrocodone, dihydrocodeine, acetaminophen, and hydromorphone. The hydrocodone level in the pilot's peripheral blood was 0.718 ug/ml, which was more than 10 times the usual upper therapeutic limit of 0.05 ug/ml. Hydrocodone and its metabolites do not undergo significant postmortem redistribution. Therefore, the measured levels of hydrocodone most likely represent the pilot's antemortem levels. If the pilot had been a novice user, this level would likely have been toxic and caused severe symptoms. However, with regular opioid use, brain physiology changes, leading to tolerance for both the desired analgesic effects and the sedative effects. As a result, incremental dosing increases are required to achieve the same effects, and long-term, chronic users may need the drug to feel and act "normally." The levels present in the pilot indicate that he was chronically taking high doses of hydrocodone. It is likely that the pilot was impaired by opioids at the time of the accident. In the high workload situation of piloting a helicopter in low altitude flight, even a small degree of impairment from the pilot's use of a high-dose of opioid would have contributed to the likelihood of an accident.

Factual Information

HISTORY OF FLIGHTOn June 20, 2015, about 0715 Pacific daylight time, a Bell 47G-5 helicopter, N4427F, impacted a fence and terrain while maneuvering about 5 miles southwest of the Salinas Municipal Airport (SNS), Salinas, California. The commercial pilot was fatally injured, and the helicopter sustained substantial damage. The helicopter was registered to and operated by Gomes Farm Air Service, Inc., under the provisions of Title 14 Code of Federal Regulations Part 137. Instrument meteorological conditions prevailed, and no flight plan was filed. The local aerial application flight originated from a loading area near the accident site about 0650. According to a tachograph card found in the wreckage, the pilot had completed six different work orders at various locations on the morning of the accident. Two witnesses, who worked for the operator, refilled the fertilizer tank on the helicopter and saw it depart from the loading area. According to the witnesses, about the time that the helicopter was expected to return, a thick fog came in, and the visibility dropped to about 15 to 20 ft. The witnesses became concerned when the helicopter failed to return for its scheduled rinse load. One of them searched for the helicopter and found the accident site nearby. PERSONNEL INFORMATIONThe pilot, age 67, held a commercial pilot certificate with airplane single-engine land and rotorcraft-helicopter ratings. He did not hold an instrument rating. Federal Aviation Administration (FAA) records indicated that the pilot's most recent third-class airman medical certificate was issued on February 10, 2014, with the limitation that the pilot "must wear corrective lenses." According to the pilot's application for this medical, he had accumulated a total of 17,500 hours of flight time of which 200 hours were within the last 6 months. AIRCRAFT INFORMATIONThe helicopter, a Bell 47G-5, serial number 7971, was manufactured in 1970 and was issued a restricted category airworthiness certificate on May 17, 2012. The helicopter's type certificate data sheet indicated that it seated two and had a maximum gross weight of 2,257 pounds. The helicopter was configured for agriculture and pest control operations. The most recent annual inspection was conducted on February 6, 2015, at a total airframe time of 8,275 hours. METEOROLOGICAL INFORMATIONAt 0653, the SNS weather reporting facility, located about 5 miles east of the accident site, reported wind calm, visibility 7 statute miles, sky condition clear, temperature 12°C, dew point 9°C, and an altimeter setting of 29.92 inches of mercury. At 0653, the recorded weather at Monterey Regional Airport, Monterey, California, about 9 miles southwest of the accident site, was wind 290° at 3 knots, visibility 1 statute mile, mist, overcast at 200 ft, temperature 12°C, dew point 11°C, and an altimeter setting of 29.93 inches of mercury. AIRPORT INFORMATIONThe helicopter, a Bell 47G-5, serial number 7971, was manufactured in 1970 and was issued a restricted category airworthiness certificate on May 17, 2012. The helicopter's type certificate data sheet indicated that it seated two and had a maximum gross weight of 2,257 pounds. The helicopter was configured for agriculture and pest control operations. The most recent annual inspection was conducted on February 6, 2015, at a total airframe time of 8,275 hours. WRECKAGE AND IMPACT INFORMATIONAn FAA inspector examined and documented the wreckage on-scene. The helicopter came to rest on a road near a lettuce field. An opening was torn in a wired fence that ran parallel to the road about 40 ft northeast of the main wreckage. Powerlines running in an east-west direction about 50 ft south of the accident site were undamaged. During the examination, the inspector did not identify any anomalies or malfunctions with the helicopter. ADDITIONAL INFORMATIONThe pilot was involved in a helicopter accident on September 3, 2010, where he received serious injuries, and the Bell 47G helicopter was substantially damaged (NTSB accident number WPR10LA446). The NTSB determined that the probable cause of the accident was the pilot's visual flight rules flight into instrument meteorological conditions, which resulted in his spatial disorientation and loss of helicopter control. MEDICAL AND PATHOLOGICAL INFORMATIONThe Monterey County Sheriff-Coroner's Office, Salinas, California, performed an autopsy of the pilot. The autopsy report listed blunt force injuries as the cause of death. The autopsy also identified an enlarged heart and significant coronary artery disease with 50-75% stenosis of two coronary arteries. The FAA's Bioaeronautical Sciences Research Laboratory, Oklahoma City, Oklahoma, performed toxicology testing of the pilot and identified 0.718 ug/ml of hydrocodone and 0.098 ug/ml of dihydrocodeine in blood and 224 ug/ml of acetaminophen, 4.61 ug/ml of dihydrocodeine, 36.917 ug/ml of hydrocodone, and 12.99 ug/ml of hydromorphone in urine. Hydrocodone is a prescription opioid identified as a Schedule II controlled substance by the Drug Enforcement Administration. It is most commonly sold in combination with acetaminophen, often with the names Vicodin and Lortab. It carries several warnings, including, "hydrocodone, like all narcotics, may impair the mental and/or physical abilities required for the performance of potentially hazardous tasks such as driving a car or operating machinery," and "alcohol and other CNS (central nervous system) depressants may produce an additive CNS depression, when taken with this combination product, and should be avoided." Dihydrocodeine and hydromorphone are each opioid analgesics, but they are also metabolites of hydrocodone. Hydrocodone's usual therapeutic levels are between 0.010 and 0.050 ug/ml. Dihydrocodeine's usual therapeutic levels are between 0.050 and 0.150 ug/ml. The pilot had reported no chronic medical conditions and no chronic medication use to the FAA. At the time of the autopsy, a small plastic baggie containing 5 tablets labeled M367 was found in the pilot's pocket. The autopsy report identified these tablets as a combination of 325 mg of acetaminophen and 10 mg of hydrocodone.

Probable Cause and Findings

The non-instrument-rated pilot's visual flight rules flight into instrument meteorological conditions, which resulted in his spatial disorientation and loss of helicopter control. Contributing to the accident was the pilot's impairment by high-dose opioid use.

 

Source: NTSB Aviation Accident Database

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