WPR18FA063

The pilot's failure to maintain clearance from the water while flying over a lake with glassy surface conditions. Contributing to the accident was the pilot's use of three impairing medications.

The commercial pilot and private pilot-rated passenger departed on a local flight in day visual meteorological conditions and climbed to a peak altitude about 2,370 ft above ground level. The airplane then entered a gradual, wings-level descent during which it began to fly over a large lake. The airplane impacted the water and subsequently sank.  The airplane was mostly intact and exhibited no evidence of mechanical failures or anomalies that would have precluded normal operation. Given the condition of the airplane, flight track, altitude data, and the proximity to land, it is likely that the pilot intentionally descended the airplane to low altitude over the lake. It is also likely that the lake exhibited a glassy surface due to low wind conditions about the time of the accident, which would have reduced depth perception and made it difficult for the pilot to judge the airplane's height above the water. Additionally, toxicology of the pilot revealed the presence of three different impairing medications. It is likely that he was experiencing combined adverse effects of these three central nervous system depressants, which contributed to his failure to maintain clearance from the water while performing low-altitude flight.

Autopsies of the pilot and passenger were performed by the Box Elder County, Utah, Office of the Medical Examiner. The autopsies determined that the cause death for both occupants was "drowning." Commercial Pilot Toxicology testing at the FAA Forensic Sciences Laboratory was negative for carbon monoxide. Testing detected ethanol at 23 mg/dl in the urine but none in the blood (blood levels are used to determine impairment). The following medications, which are generally considered not to be impairing, were also detected: the pain and fever medication acetaminophen; the nasal decongestant oxymetazoline; the prostate treatments tamsulosin and terazosin; and the antidepressant venlafaxine, at 0.054 µg/ml in blood, and its metabolite, desmethylvenlafaxine, in blood. Testing also detected the following potentially impairing drugs in blood: gabapentin at 3.897 µg/ml; hydrocodone at 0.082 µg/ml; its active metabolite, dihydrocodeine, at 0.024 µg/ml; and morphine at 0.078 µg/ml. Gabapentin is an anti-seizure medication also used to treat chronic pain and is marketed under various names, including Neurontin. It is a central nervous system depressant and may cause symptoms including somnolence, dizziness, impaired coordination, involuntary eye movement and fatigue. It carries the warning: "prescribers and patients should be aware that patients' ability to assess their own driving competence, as well as their ability to assess the degree of somnolence caused by gabapentin, can be imperfect." It is only available by prescription. This medication is disqualifying for FAA medical certification. Hydrocodone is a prescription, short-term use medication used to relieve severe pain. Hydrocodone is in a class of medications called opiate (narcotic) analgesics. Hydromorphone and dihydrocodeine are active metabolites of hydrocodone. Hydrocodone carries the warnings: "exposes users to the risks of addiction, abuse, and misuse," and "profound sedation, respiratory depression, coma, and death may result from the concomitant use of hydrocodone … with benzodiazepines or other CNS depressants (e.g., non-benzodiazepine sedatives/hypnotics, anxiolytics, tranquilizers, muscle relaxants, general anesthetics, antipsychotics, other opioids, alcohol)." The range of blood levels where hydrocodone is considered to have therapeutic psychoactive effects is between 0.01 and 0.05 µg/ml. Morphine is a prescription medication used to relieve moderate to severe pain. It is in a class of medications called opiate (narcotic) analgesics. The medication has the potential to impair mental and/or physical ability required for the performance of potentially hazardous tasks, e.g. flying, driving, and operating heavy machinery. This medication is disqualifying for FAA medical certification. Morphine, hydrocodone, and gabapentin are all central nervous system depressants and have a combined additive effect on toxic drug effects, including sedation, slowed or difficult breathing, and death. On his FAA medical certificate application, the pilot reported that he used the anti-inflammatory medication oxaprozin to treat joint pain and the acid-reducing medication omeprazole for stomach protection. These medications are generally considered not to be impairing. A review of the pilot's primary care medical records between February 2015 and December 2017 revealed that he was receiving ongoing testosterone replacement injections and had lower back pain and left knee arthritis. His active medications as of December 2017 included the antihistamine nasal spray azelastine; the acid-reducing medication omeprazole; the anti-inflammatory medication oxaprozin; the cholesterol medication fenofibric acid; the nasal steroid spray fluticasone; the prostate medication terazosin; and the oral antifungal medication terbinafine. The nasal spray azelastine carries a warning of sedation, while the other medications are generally not considered to be sedating or impairing. The records contained no documentation of treatment for depression or recent opioid prescriptions. Passenger Toxicology testing was negative for carbon monoxide and volatiles. Tamsulosin was detected in the urine and blood. Tamsulosin is a prescription medication used to treat the symptoms of an enlarged prostate. Tamsulosin is in a class of medications called alpha blockers and generally not considered to be impairing. The 1453 recorded weather observation at OGD, included wind from 320° at 4 knots, 10 miles visibility, clear sky, temperature 6°C, dew point, -2°C, and an altimeter setting of 30.15 inches of mercury. No significant weather or precipitation was present in the area at the time of the accident. Commercial Pilot The pilot held a commercial pilot certificate with ratings for airplane single-engine land and instrument airplane. In addition, he held a flight instructor certificate with a rating for airplane single-engine. The pilot held a third-class FAA airman medical certificate issued on July 11, 2016, with the limitation, "must have available glasses for near vision." On the application for that certificate, the pilot reported 5,587 total hours of flight experience. Pilot Rated Passenger The pilot-rated passenger held a private pilot certificate with an airplane single-engine land rating. Review of his logbook indicated 375.1 total hours of flight experience. His most recent third-class FAA airman medical certificate was issued on April 10, 2014, with a limitation that stated, "must have available glasses for near vision." His medical certificate expired for all classes in April 2016. According to the recovery specialist, the wreckage was located in the northern portion of the Great Salt Lake at a depth of about 20 ft and elevation of about 4,198 ft, msl. Sonar imagery indicated that the main wreckage came to rest inverted, oriented on a heading of about 195°. The engine was about 110 ft from the main wreckage on a heading of about 108°. A diver who participated in the recovery stated that the visibility in the water was less than 1 ft. He reported that the vertical stabilizer and the left horizontal stabilizer and elevator appeared to be intact. He also confirmed that the airplane was inverted. He felt his way to the forward portion of the fuselage and stated that there appeared to be no damage, wrinkling, or buckling of the left side of the fuselage. The door windows were broken on each door, in order to give access to the door handle and open the door during the recovery. The wreckage was recovered from the lake on March 8, 2018. The main wreckage was mostly intact and consisted of both wings, the fuselage, and the empennage. The rudder counterweight and the right fuel cap had separated and were not recovered. All flight control surfaces remained attached. Flight control cable continuity was established when the airplane was removed from the water by the recovery personnel. The aileron cables were then cut to aid in recovery. Airframe Examination The wind screen was fragmented, and the firewall and instrument panel were partially attached. Both cabin doors remained attached. The right door window was separated and located with the main wreckage. The baggage door was closed and locked. The fuel selector handle was observed in the right tank position; however, it was separated from the valve and free to rotate. The fuel selector valve was removed and found in the "both" position. The valve was functionally tested in all positions with no anomalies. The magneto switch was in the "both" position and the flap selector handle was in the retracted position. All circuit breakers were observed in the closed position. The right wing remained attached to the fuselage at the wing root and was separated during the recovery. The wing was bent upward about 135° near midspan and displayed extensive damage. The leading edge was displaced downward about 45° from the root to