CEN24FA170

The private pilot and pilot-rated passenger were returning to their home airport following a personal flight. About 7 miles from the destination airport, the airplane’s airspeed increased, and it entered a steep descent. Witnesses reported that the airplane descended rapidly and impacted a wooded area. Witnesses also reported conflicting observations regarding whether the engine was operating normally. The engine examination did not reveal any preimpact anomalies, and the shattered and widely dispersed wooden propeller blade fragments were consistent with engine power at impact. The airframe examination did not reveal any preimpact mechanical malfunctions or failures that would have precluded normal operation. Toxicological testing of the pilot identified ethanol at low levels in several of the specimens and was not detected in brain tissue. Based on these results, some or all of the small amount of detected ethanol may have been from postmortem production rather than alcohol consumption, and it is unlikely that ethanol effects contributed to the accident. As a result of his heart disease, the pilot was at some increased risk of a sudden impairing or incapacitating cardiac event, such as chest pain, arrhythmia, or heart attack. The autopsy identified no evidence of such an event. However, an acute cardiac event occurring immediately before death may leave no reliable autopsy evidence. Whether the pilot’s heart disease contributed to the accident could not be determined. Toxicological testing of the pilot-rated passenger identified two oral medications commonly used to treat diabetes. People with medication-treated diabetes are at risk for both abnormally high blood sugar (from diabetes) and abnormally low blood sugar (from medication effects). Short-term effects of high blood sugar may include decreased cognitive performance, including slower information processing speed, decreased executive function and attention. Low blood glucose may cause difficulty concentrating, impaired task performance, and, in extreme cases, diminished consciousness, seizure, and death. The pilot-rated passenger’s postmortem urine glucose concentration is inconsistent with a markedly high antemortem blood glucose; however, it provides no information about whether his blood sugar may have been low. It also is unknown if the pilot-rated passenger had less severe symptoms of diabetes, such as fatigue or blurred vision or chronic complications associated with diabetes, such as vision loss, neuropathy, or kidney disease. As a result of his heart disease, the pilot-rated passenger was at some increased risk of a sudden impairing or incapacitating cardiac event, such as chest pain, arrhythmia, or heart attack. The autopsy identified no evidence of such an event. However, such an event does not leave reliable autopsy evidence if it occurs immediately before death. It is unknown what role the pilot-rated passenger had, if any, in aircraft operations and flight safety. Whetherthe effects of the pilot-rated passenger’s use of metformin and glipizide or his heart disease contributed to the accident cannot be determined. Although either occupant could have experienced a sudden incapacitating medical event while manipulating the flight controls during the descent, the remaining occupant may have had insufficient time or opportunity to recover the airplane before impact. However, the investigation could not determine which occupant, if either, was manipulating the flight controls at the time of the accident. Therefore, whether either occupant experienced an incapacitating medical event that contributed to the accident could not be determined.

The airplane was built by the pilot, and the first flight was on July 30, 1997. On July 7, 2022, at 1,695.5 hours total time, he completed a condition inspection on the airplane. On July 7, 2023, at 1,703.4 hours total time, he removed the old dihedral wings and installed square wings. On July 9, 2023, he completed an airframe condition inspection. On August 4, 2023, at 1,712.4 hours total time, the most recent maintenance log entry stated, “have 9 [hours] on new wings.” On April 30, 2024, at 1418 eastern daylight time, a Zodiac CH-601 HDS airplane, N6271F, was destroyed when it was involved in an accident near Bristol, Indiana. The private pilot and pilot-rated passenger were fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot’s wife reported that the pilot intended to fly his airplane with the pilot-rated passenger to Branch County Memorial Airport (OEB), Coldwater, Michigan, for lunch and then return to Elkhart Municipal Airport (EKM) Elkhart, Indiana, where the airplane was hangared. She stated that this was a very popular flight for the pilot, and he usually returned within three hours. ADS-B data indicated that the airplane departed EKM at 1152 and landed at OEB at 1225. The return flight departed OEB at 1339 and proceeded southwest at a cruise altitude between 4,200 ft mean sea level (msl) and 4,500 ft msl and a true airspeed of about 80 kts. At 14:15:44, the airplane started a descent and continued west toward EKM. During the next 2 minutes, the true airspeed increased to about 110 kts and the average descent rate was about 600 ft per minute (fpm). At 14:17:57, the airspeed increased to about 120 kts, with a descent rate of more than 7,000 fpm. The final data point was recorded at 14:18:05 at an altitude of 1,635 ft msl (870 ft agl), which was 7 nautical miles east of EKM, and about 400 ft east of the accident site. A witness, labeled as witness 1 in the figure, stated that the airplane flew directly overhead from the east to the west, then entered a nosedive. The engine sounded like it was “cutting in and out” and was not making a consistent sound as it descended. The airplane impacted the ground and produced a loud boom. At the accident site, there was a strong smell of fuel but there was no smoke or fire. Another witness, witness 3 in the figure, stated that she was outside of her house facing southeast when she heard the airplane behind her. She turned around and saw the airplane descending straight down toward the ground. She thought she saw the top of the airplane because she didn’t notice any wheels. She did not see any smoke or fire coming from the airplane. The engine was very loud and continued operating loudly until the impact, which sounded like a loud explosion. The yellow line in the figure is the estimated sight path from her location to where she observed the airplane in a vertical descent. Figure 1. Google Earth image showing the ADS-B flight track,witness locations, and accident site. Pilot At the request of the Elkhart County Coroner’s Office, the Western Michigan University School of Medicine Medical Examiner and Forensic Services performed the pilot’s autopsy. According to the associated coroner’s report, the pilot’s cause of death was multiple blunt force injuries, and his manner of death was accidental. The pilot’s autopsy identified up to 50% narrowing of the coronary arteries. No further anatomic detail about the coronary artery narrowing was provided in the autopsy report. Moderate plaque was identified in the aorta. The remainder of the autopsy, including visual examination of the heart, did not identify other significant natural disease. Microscopic evaluation of the heart was not performed. Axis Forensic Toxicology performed toxicological testing of postmortem blood from the pilot. Ethanol was detected at 0.026 g/dL. No other tested-for substances were detected. The FAA Forensic Sciences Laboratory also performed toxicological testing of postmortem specimens from the pilot. Ethanol was detected in cavity blood at 0.011 g/dL and in liver tissue at 0.013 g/hg. Ethanol was not detected in brain tissue. Losartan, metoprolol, and desmethylsildenafil were detected in liver and muscle tissue. Pilot-rated passenger At the request of the Elkhart County Coroner’s Office, Western Michigan University School of Medicine Medical Examiner and Forensic Services performed the pilot-rated passenger’s autopsy. According to the associated coroner’s report, the pilot-rated passenger’s cause of death was multiple blunt force injuries, and his manner of death was accident. The pilot-rated passenger’s autopsy identified up to 60% narrowing of the coronary arteries. No further anatomic detail about the coronary artery narrowing was provided in the autopsy report. Moderate plaque was identified in the aorta. The remainder of the autopsy, including visual examination of the heart, did not identify other significant natural disease. Microscopic evaluation of the heart was not performed. The FAA Forensic Sciences Laboratory performed toxicological testing of postmortem specimens from the pilot-rated passenger. Metformin, glipizide, atorvastatin, metoprolol, lisinopril, hydrochlorothiazide, chlorothiazide, and oxprenolol were detected in liver tissue and urine. Salicylic acid was detected in urine but not in liver tissue. The medications detected are commonly prescribed for treatment of diabetes. Base reflectivity weather radar imagery from Fort Wayne, Indiana, (KIWX) valid for the period surrounding the accident time, did not reveal any pertinent meteorological echoes across the accident region. The KIWX wind profile revealed the wind below 7,000 ft remained between 15 and 25 knots from the west to west-northwest. At 1327, a National Weather Service terminal aerodrome forecast was issued for South Bend International Airport (SBN), South Bend, Indiana, which forecast the following conditions at the accidenttime: wind from 290° at 11 knots, visibility greater than 6 statute miles and sky clear. The pilot was seated in the left seat and the pilot-rated passenger was seated in the right seat. According to the pilot’s flight logbook, he had flown the accident airplane with the pilot-rated passenger at least 9 times since 2016. The pilot’s current flight logbook entries began on January 20, 2016, and ended on October 1, 2023. During that time, the pilot accumulated 447.6 flight hours exclusively in the accident airplane. The pilot-rated passenger, who was a flight instructor and airline transport pilot, logged 82.9 flight hours since 2016 according to his flight logbook. Review of the flight logbook showed that the pilot-rated passenger had accumulated 12,344.9 hours total time. On August 15, 2023, he completed a flight review for the accident pilot. The investigation was unable to determine who was manipulating the flight controls at the time of the accident. Postaccident examination revealed that the airplane impacted trees and terrain in a near-vertical attitude, with the left wing low and then nosed over. The left wing exhibited chordwise crushing to the leading edge and the outboard half of the wing was bent aft. The right wing sustained impact damage and hydraulic deformation to the inboard leading edge near the fuel tank consistent with fuel present. The outboard 2 ft of the right wing sustained ground impact damage and was bent aft. The airplane was equipped with a "Y" center-mounted elevator and aileron control stick assembly, which remained installed and sustained impact damage. The elevator and rudder control cables were traced from their control surfaces to the cockpit through locations where first responders had cut the fuselage during their extraction efforts. The aileron control cables were continuous from the cockpit to the aileron bellcrank. The engine remained partially attached to the firewall and was crushed into the cockpit. The engine sustained significant impact damage to the front and to the rear accessories, but the case and cylinders remained intact. There were no holes in the case or signs of catastrophic failure. The wooden propeller blades were impact-separated at the propeller hub; pieces of the blades were found shattered and dispersed around the accident site. Postaccident examination revealed no preimpact mechanical malfunctions or failures with the airplane that would have precluded normal operation.