CEN23FA258

The pilot’s improper preflight fuel planning and inflight fuel mismanagement, which resulted in a total loss of engine power due to fuel exhaustion, and his subsequent failure to maintain adequate airspeed during the forced landing, which resulted in the airplane exceeding its critical angle of attack and entering an aerodynamic stall at a low altitude. Contributing to the accident was the pilot’s impairment from his use of multiple impairing substances.

The private pilot and the passenger were conducting a personal cross-country flight in the airplane that the pilot recently purchased. The pilot did not have previous flight experience in the airplane make/model before he took possession of the airplane the day before the accident. According to the passenger, the airplane had full fuel tanks (48 gallons usable) before the previous flight leg. Based on available flight track data, the previous flight leg was at least 2.9 hours in duration. The passenger reported that after the previous flight leg, the right fuel gauge indicated “empty” and the left fuel gauge indicated “1/4” tank remaining. Before the accident flight, the pilot was unable to dispense fuel from the self-serve fuel pump and so believed that there was no fuel available at the airport. However, the airport manager, who was not present at the time, stated that the self-serve fuel pump operated normally and there was fuel available when he tested it after the accident. According to the passenger, the pilot decided that the airplane had enough fuel for the flight. Based on ADS-B flight track data and recorded voice transmissions, about 38 minutes into the flight the airplane was about 5.3 statute miles (sm) from the intended destination airport when the pilot transmitted that the airplane was “low on fuel.” Then, about 2 minutes 20 seconds later, the pilot transmitted “…engine out, coming in runway five, engine out.” At that time, the airplane was about 1.8 sm west-southwest of runway 5 and about 600 ft above the runway threshold elevation. Airplane performance calculations using ADS-B flight track data revealed that the pilot did not establish and maintain best glide speed after the loss of engine power; the airplane was 15-20 mph below best glide speed. However, based on the airplane’s expected glide ratio (10:1) at best glide speed, it is unlikely the airplane had enough altitude remaining to safely reach the runway even if the pilot maintained best glide speed. The final ADS-B track point placed the airplane about 0.8 sm from the runway threshold, about 200 ft above ground level (agl), at a calibrated airspeed of about 61 mph, and a descent rate of 450 feet per minute (fpm). According to the passenger, the pilot was unable to restore engine power and intended to land on the lake to avoid the trees and houses that surrounded the lake. However, while above the lake, the airplane “stalled” as it descended through tree-top height. The aerodynamic stall resulted in the airplane’s nose dropping almost straight down. The airplane immediately started to sink after it impacted the lake. The passenger recalled remaining conscious but unable to see anything in the murky green water. Believing that she would drown, she instinctively unfastened her seat belt and swam to the surface. The pilot did not emerge from the submerged airplane. After the accident, the passenger told at least one individual who provided her assistance that the airplane ran out of fuel while on approach to the airport. The airplane sustained substantial damage to the fuselage and both wings. Examination of the wreckage did not reveal any evidence of a mechanical malfunction of the airplane or its engine. However, several engine components exhibited signatures consistent with an excessively rich air-to-fuel ratio. The passenger reported that the pilot had difficulty leaning the engine and, specifically, that the engine would begin “stumbling” after the mixture control was pulled 1.5 to 2 inches aft of full rich. The engine “stumbling” as described by the passenger when the mixture was adjusted was consistent with an excessively lean air-to-fuel mixture. Therefore, based on the available evidence, it is likely the pilot did not properly lean the air-to-fuel mixture during the accident flight. Consequently, the fuel consumption rate during the flight was greater than he might have anticipated. Based on the fuel quantity gauge indications reported by the passenger, the airplane had about 6 gallons of fuel available before the accident flight. According to the airplane owner’s manual, the engine, operated at 75% brake horsepower with a properly leaned air-to-fuel mixture, would result in a fuel consumption rate of 8 to 8.5 gallons per hour (gph). Operated as such, the estimated 6 gallons of fuel would have provided 42-45 minutes of flight time with a properly leaned engine. The loss of engine power occurred at least 40 minutes into the flight (that is, not including the time associated with the engine startup, taxi, takeoff). Based on the available information, it is possible the airplane had enough fuel at departure to reach the intended destination airport if the pilot had properly leaned the engine during the flight. Additionally, the minimal distance remaining to the intended destination airport (1.8 sm) when the loss of engine power occurred further supports that the airplane might have departed with enough fuel to reach the airport. However, it is unlikely the airplane departed with the additional 30 minutes of fuel reserve required by fuel-planning regulations for day visual flight rules flights. The pilot’s decision to depart with barely enough fuel to make the flight under ideal operating conditions resulted in fuel exhaustion and total loss of engine power at the end of the flight. Toxicology results indicate that the pilot had used a delta-8-THC product. Delta-8-THC has psychoactive and intoxicating effects that can impair motor coordination, reaction time, decision making, problem solving, and vigilance. However, the precise timing of the pilot’s last cannabis use, and whether it was causing significant impairing effects at the time of the accident, could not be determined from the measured levels of delta-8-THC and its metabolites. However, products containing Delta-8 THC have not been evaluated or approved by the Food and Drug Administration for safe use in any context. Toxicology results also indicated that the pilot had used diphenhydramine. The measured diphenhydramine level in blood would be above the typical therapeutic range had it been measured in a living person. However, interpretation of postmortem diphenhydramine levels is complicated by the drug’s significant potential for postmortem redistribution. Regardless, the measured level of diphenhydramine was from the pilot’s peripheral blood, which is the preferred postmortem blood specimen type. Overall, the diphenhydramine level in postmortem peripheral blood indicates that the pilot likely was experiencing impairing effects of his use of diphenhydramine, but the specifics of impairment could not be determined from the measured levels alone. Diphenhydramine may cause cognitive and psychomotor slowing and drowsiness. The FAA recommends a 60-hour waiting period from the last dose of diphenhydramine to piloting an aircraft to allow sufficient time for the drug to be cleared from circulation. Toxicology results also revealed the pilot used the prescription antidepressant medication fluoxetine. The pilot did not report the use of fluoxetine when he applied for his last aviation medical examination, completed more than 11 years before the accident, and the reason for its use is not documented. It is possible that fluoxetine and/or the underlying condition for which it was being used may have had some performance-impairing effects. However, no more-specific conclusions about impairment can be drawn from the reviewed medical evidence. Based on the pilot’s improper preflight fuel planning and decision-making, inflight fuel mismanagement, and failure to maintain adequate airspeed and control of the airplane during the forced landing, it is likely he was experiencing impairing effects from the detected substances.

A review of the pilot’s flight logbook established that he began his flight training on September 3, 2011, and received his private pilot certificate on November 2, 2012, with 74.1 hours total flight experience. The final logbook entry was dated June 18, 2023, at which time he had 147.4 hours total flight experience. The entirety of his logged flight experience was flown in Cessna 172 airplanes. The pilot’s last regulatory flight review was completed on October 7, 2022. Based on available flight track data, the pilot flew three additional flights after his final logbook entry. The three flights were flown after he purchased the accident airplane. On June 25, 2023, the pilot flew a 3.3-hour flight from LRU to SWW and a 2.9-hour flight from SWW to DEQ. Then, on the day of the accident, the pilot flew the 0.7-hour flight from DEQ to HOT. The combined 6.9 hours was the pilot’s only flight experience in a Cessna 177 airplane. When the pilot’s logged flight time was combined with the three additional flights, he had 154.3 hours total flight experience, of which 142.3 hours were flown as pilot-in-command. The pilot had flown 11.6 hours in the previous year, 9.6 hours in the previous 6 months, 8.4 hours during the past 90 days, and 7.4 hours during the 30 days before the accident. A review of available maintenance documentation established that the airframe, engine, and propeller had accumulated 2,610.9 hours since new. The engine had accumulated 1,103.5 hours since the last top overhaul. The airplane had accumulated 171.4 hours since the last annual inspection completed on August 31, 2022. According to the Cessna 177 Owner’s Manual, the airplane was equipped with a 49-gallon capacity (48 gallons usable) fuel system, consisting of two 24.5-gallon wing fuel tanks (24 gallons usable each). The fuel selector valve positions included left, right, both, and off. The airplane’s expected fuel consumption rate was 8 to 8.5 gph if the engine was operated at 75% brake horsepower and properly leaned for cruise flight, yielding an airplane fuel endurance of 5.7 to 6 hours. Alternatively, if the engine was operated at less than 75% brake horsepower and leaned for cruise flight, the expected fuel consumption rate was 6 to 8 gph and the fuel endurance was 6 to 8 hours. The airplane had a glide ratio of about 10:1 when flown at the best glide speed of 80 mph, with the flaps retracted, a windmilling propeller, and zero wind. The engine-off, wings-level, aerodynamic stall speed at maximum gross weight with fully extended flaps was 53 mph. Similarly, the stall speed was 64 mph with the flaps fully retracted. According to a review of FAA medical records, the 49-year-old pilot’s last aviation medical examination was completed on March 8, 2012. At that time, the pilot reported having high blood pressure (hypertension) and a prescription for lisinopril. Lisinopril, an angiotensin-converting enzyme (ACE) inhibitor medication used to treat hypertension, is acceptable for pilot use. The pilot was issued a third-class medical certificate without limitation. The medical certificate was not valid after March 31, 2017. The pilot subsequently completed the BasicMed Comprehensive Medical Examination Checklist on August 16, 2022, and the BasicMed online course on October 12, 2022. The Arkansas State Medical Examiner’s Office performed the pilot’s autopsy. According to the pilot’s autopsy report, the cause of death was drowning associated with multiple blunt force injuries, and the manner of death was accident. FAA toxicology testing detected delta-8-tetrahydrocannabinol (delta-8-THC) in peripheral blood at 6.4 ng/mL and in urine at 5.9 ng/mL. Carboxy-delta-8-THC was detected in peripheral blood at 142.7 ng/mL and in urine at 1,278.5 ng/mL. 11-hydroxy-THC was detected in peripheral blood and urine. Diphenhydramine was detected in peripheral blood at 104 ng/mL and in urine at 1,588 ng/mL. Fluoxetine was detected in peripheral blood at 1,044 ng/mL and in urine at 827 ng/mL. Norfluoxetine was detected in peripheral blood at 1,243 ng/mL and detected in urine at 970 ng/mL. Metoprolol and atorvastatin were detected in peripheral blood and urine. Lisinopril was detected in urine and was not detected in peripheral blood. Carboxyhemoglobin and ethanol were not detected in blood. Delta-8-THC is a psychoactive cannabinoid chemical. Although delta-8-THC is similar to the primary psychoactive chemical in cannabis (delta-9-THC), very little delta-8-THC is present in the cannabis plant. Delta-8-THC used in consumer products typically is chemically manufactured from cannabidiol (CBD), another chemical in the cannabis plant. Delta-8-THC products are often marketed as “hemp” products, which consumers may not associate with psychoactive effects. Delta-8-THC is available in a variety of over-the-counter products for oral consumption, smoking, and inhalation. Delta-8-THC has psychoactive and intoxicating effects that can impair motor coordination, reaction time, decision making, problem solving, and vigilance. The potency and purity of delta-8-THC varies widely in consumer products. Delta-8 THC products may contain impurities including delta-9 THC. Delta-8 THC products have not been evaluated or approved by the Food and Drug Administration for safe use in any context. Carboxy-delta-8-THC is a non-psychoactive metabolite of delta-8-THC. 11-hydroxy THC is a psychoactive metabolite of both delta-8-THC and delta-9-THC (the FAA Forensic Sciences Laboratory does not distinguish between 11-hydroxy-delta-8-THC and 11-hydroxy-delta-9-THC). Diphenhydramine is a sedating antihistamine medication widely available over the counter in multiple sleep aids and cold and allergy products. Diphenhydramine may cause cognitive and psychomotor slowing and drowsiness. It typically carries a warning that it may impair performance of tasks like driving and operating heavy machinery. The therapeutic range of diphenhydramine in the plasma of living persons is about 25 ng/mL to 100 ng/mL. The blood to plasma ratio for diphenhydramine is reported to be 0.7 to 0.8. The FAA recommends a 60-hour waiting period from the last dose of diphenhydramine to piloting an aircraft, to allow sufficient time for the drug to be cleared from circulation. Fluoxetine is a prescription selective serotonin reuptake inhibitor (SSRI) antidepressant medication that may be used for treating depression, panic disorders, and bipolar disorders. The FAA considers fluoxetine, used as a single agent, to be conditionally approved for medical certification by Special Issuance if the pilot is otherwise qualified, subject to case-by-case evaluation of the underlying condition and its treatment. Norfluoxetine is a metabolite of fluoxetine. The airplane sustained substantial damage when it impacted lake water in a near-vertical, nose-down pitch attitude. The airplane sank and was found inverted in 7 to 13 ft of water. The accident site was about 0.66 sm west-southwest of the runway 5 threshold at HOT. Wreckage recovery personnel floated the airplane to the surface and towed it to a public boat launch where it was recovered to shore, as shown in figure 4. Figure 4. Airplane wreckage after it was recovered to a boat launch. Airframe Both wings remained attached to their respective fuselage attachment points. The leading edge of both wings were crushed aft. The cockpit windshield and the back window were separated. The left cabin door separated from the fuselage and was not observed during the examination. The engine cowling separated from the nose and was not observed during the examination. All flight control surfaces remained attached to their respective hinge points. Flight control cable continuity was confirmed from the cockpit controls to their respective flight control surface. The flap actuator jackscrew was found fully extended consistent with the wing flaps fully extended at impact. The stabila