ERA24FA072 · Hawker Beechcraft Corp G36

The pilot departed for a local flight shortly before the accident occurred. Recorded data showed that about 10 minutes into the flight, while about 3,000 ft mean sea level, groundspeed began to slow considerably, which was followed by a descent towards a large lake. The flight track continued over the lake and the loss of groundspeed and altitude also continued. A witness located near the accident site observed the airplane flying low over the water and then enter a right bank towards a tree line along the shoreline. The witnesses did not recall hearing any engine sounds. The airplane impacted the trees, then abruptly descended and impacted a parking lot. The airplane exploded on impact, and a large fire developed around the entire airplane. A distant surveillance camera captured the final moments of flight, which showed the airplane in a flight path consistent with the witness reports. Examination of the airframe and engine revealed no evidence of preimpact mechanical malfunctions or failures. Extensive thermal damage prevented the investigation from fully evaluating the airplane’s fuel system. About 10 gallons of fuel was recovered from the right main fuel tank. The other tanks were breached, destroyed, or empty of fuel. The fuel selector was not recovered. The thermal damage also prevented the recovery of any non-volatile memory stored in the cockpit primary and multi-function displays. Based on the available evidence, it is likely that the airplane’s engine lost power; however, here was no evidence that the engine experienced a catastrophic mechanical failure and there was sufficient fuel on-board. Due to the thermal damage sustained to the airplane, the reason for the loss of power could not be determined. The pilot’s severe coronary artery disease placed him at increased risk of a distracting, distressing, impairing, or incapacitating cardiovascular event, such as angina, arrhythmia, or heart attack. There is no autopsy evidence that such an event occurred, but such an event does not leave reliable autopsy evidence if it occurs just before death. Overall, there is insufficient evidence to determine whether the pilot’s severe coronary artery disease contributed to the accident.

Postimpact fire provides a plausible explanation for the pilot’s carboxyhemoglobin result, particularly considering the possibility of some passive carbon monoxide absorption into cavity blood after death. The cyanide level in the pilot’s cavity blood likely was due to exposure to fire smoke, and was not likely due to engine exhaust exposure, because cyanide typically is produced by combustion of nitrogen-containing polymers. Overall, available postmortem evidence provides no clear indication that preimpact carbon monoxide or cyanide poisoning occurred, that in-flight fire occurred, or that the pilot breathed during the known fire.

Verbatim NTSB analysis and probable cause from the NTSB dataset