CEN20LA374

The pilot was on the final leg of a cross-country flight at the time of the accident. A representative of the fixed base operator (FBO) reported that, during a fuel stop after the initial flight leg, the pilot landed without announcing his intentions over the radio. The pilot subsequently requested the airplane be fueled but remained in the airplane and stared straight ahead as it was being fueled. Afterward, the pilot exited the airplane and ate his lunch in the FBO conference room. He was offered a bottle of water but did not acknowledge. During the second flight leg, air traffic controllers observed altitude and course deviations and noted slow radio responses that caused them to be concerned that the pilot was hypoxic or disoriented. They diverted the pilot to an intermediate airport and subsequently declared an emergency on the pilot’s behalf. He was met by emergency medical personnel but refused treatment. The pilot subsequently departed for the intended destination airport without refueling. During the final flight leg, position data depicted the pilot altering course as the airplane approached a line of storms. He proceeded about 15 miles away from the storms but then abruptly reversed course toward the intended destination airport and again approached the line of storms. About 4 minutes before the accident and as the airplane continued to approach the line of storms, the pilot entered a descent from 7,000 ft, which appeared to continue until impact with the surface of a lake. The airplane came to rest in about 12 ft of water. Post-recovery airframe and engine examinations did not reveal any anomalies consistent with a preimpact failure or malfunction. Based on the available information, the airplane flew about 4.5 hours since being fully fueled. However, due to submersion in the lake, no estimate could be made concerning the remaining fuel onboard at the time of the accident. Without additional data, whether fuel exhaustion occurred could not be determined. The pilot was reportedly slow to respond during conversations, sleeping excessively, and seemed to have significant difficulty focusing in the weeks before the accident, which was noted to be unusual for the pilot. His autopsy revealed a previously undiagnosed brain tumor that had a compressive effect on his brain. Based on the autopsy findings and information about the pilot’s behavior on the day of the accident and during the preceding weeks, the pilot was likely impaired by effects of his brain tumor at the time of the accident. The autopsy also identified two peripheral blood clots in the pilot’s left lung and blood clots in the deep veins of his left lower leg. Blood clots in deep leg veins may develop for a variety of reasons, including from slowed blood flow during prolonged sitting and from pro-clotting effects of cancer. However, whether symptoms from the blood clots contributed to the accident could not be determined from available information.

The airplane was topped off with 76.1 gallons of 100LL aviation fuel during the pilot’s stop at IRK. No fueling or other services were requested by the pilot during the stop at STC. The airplane fuel capacity totaled 84 gallons and was distributed between two 25-gallon main tanks and two 17-gallon wingtip tanks. The airplane owner’s manual noted a fuel consumption rate of 14.0 gph at 75% engine power. However, no data were available related to the actual fuel consumption during the accident flight or the extent to which the engine mixture was leaned. Maintenance records for the airplane were not available to the NTSB. However, a copy of the most recent annual inspection logbook endorsement was provided by maintenance personnel. On September 1, 2020, about 2007 central daylight time, a Piper PA-28-235 airplane, N8957W, was substantially damaged when it was involved in an accident near Walker, Minnesota. The pilot was fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. Automatic dependent surveillance – broadcast (ADS-B) position data indicated that the pilot departed Natchez-Adams County Airport (HEZ), Natchez, Mississippi, about 0912 and proceeded to Kirksville Regional Airport (IRK), Kirksville, Missouri, arriving about 1303. A representative of the IRK fixed base operator (FBO) reported that the pilot landed without announcing his intentions on the airport common traffic advisory frequency. He requested that the airplane be topped off with fuel. During that time, the pilot remained in the airplane and stared straight ahead. Afterward, the pilot exited the airplane with his lunch and ate in the FBO conference room. He was offered a bottle of water but did not acknowledge. The pilot departed IRK about 1436 with an intended destination of Bemidji Regional Airport (BJI), Bemidji, Minnesota. After takeoff, the pilot proceeded northbound and climbed to about 13,000 ft mean sea level (msl) before descending and maintaining 12,000 ft msl. About 1629, the pilot initiated a descent to 8,000 ft msl and then to 6,000 ft msl. About 7 minutes after leveling at 6,000 ft msl, the airplane altitude began to vary between 5,225 ft msl and 6375 ft msl. During the flight, Minneapolis Air Route Traffic Control Center controllers became concerned that the pilot might be suffering from hypoxia due to the altitude and course deviations, and slow communication responses from the pilot. Controllers diverted the flight to St Cloud Regional Airport (STC), St. Cloud, Minnesota, and subsequently declared an emergency on the pilot’s behalf. Upon landing at STC, about 1734, the pilot was met by emergency medical personnel but refused treatment. He subsequently departed STC for BJI about 1832 under visual flight rules and without air traffic services. According to the FBO at STC, the airplane was not fueled before departure. ADS-B data depicted the airplane proceeding northbound toward BJI when the flight track abruptlyturned eastbound. The airplane over flew Leech Lake and continued about 15 miles southeast. The flight track then reversed course and proceeded northwest to the vicinity of Leech Lake. This was also in the direction of BJI. About 2003, the airplane entered a descent from 7,000 ft about the time it crossed over the eastern shore of Leech Lake. The final ADS-B data point was recorded at 2007:39 with a corresponding altitude of 2,575 ft. The airplane subsequently impacted the lake about 0.55 mile southwest of the final data point. The lake elevation was about 1,290 ft and the water depth was about 12 ft at the accident site. The pilot’s brother and friend noted that in the weeks before the accident, the pilot was slow to respond during conversations, was sleeping excessively, and seemed to have had significant difficulty focusing. This was unusual since the pilot was known to be meticulous and detail oriented. The pilot’s autopsy identified a 3 centimeter (cm) × 3 cm × 3 cm mass in his brain. The mass appeared to be a glioblastoma multiforme, which is an aggressive, fast-growing type of cancerous brain tumor. The tumor had a localized area of bleeding and was causing compression and shift of surrounding brain tissue. The autopsy also identified two peripheral blood clots in the pilot’s lung and blood clots in the deep veins of his left lower leg. The pilot’s cause of death was recorded as probable drowning. Postmortem toxicological testing detected the pilot’s blood pressure medication metoprolol. Metoprolol is generally not considered impairing. The leading edge of a line of thunderstorms was located immediately north of the site at the time of the accident. Visual conditions prevailed outside of the storms themselves with light rain, wind gusts, and lightning in the vicinity. Advisories for thunderstorms, moderate turbulence, and low-level wind shear were in effect for the site at the time of the accident. There was no record of the pilot obtaining an official weather briefing. However, the pilot did access a radar composite map and regional radar animation prior to departing IRK about 5.5 hours before the accident. At that time, the line of thunderstorms had not yet developed, and the advisories had not yet been issued. The pilot’s logbook was not available to the National Transportation Safety Board (NTSB) during the investigation. Post-recovery airframe and engine examinations did not reveal any anomalies consistent with a preimpact failure or malfunction.