History of Flight
On October 27, 2021, at 1817 central daylight time, a Beech B36TC airplane, N75RM, was substantially damaged when it impacted a cornfield near Lena, Wisconsin. The pilot was fatally injured. The airplane was operated as a personal flight under Title 14 Code of Federal Regulations Part 91.
The flight departed from Fort Worth Meacham Airport (FTW), Fort Worth, Texas, about 1357, headed northeast. According to the pilot's mechanic, the intended destination was Camdenton Memorial – Lake Regional Airport (OZS), near Camdenton, Missouri, for an annual inspection.
About 1427, the airplane leveled off near 15,500 ft mean sea level (msl). Around 1451, it entered a climb, and shortly after, its flightpath began to deviate as it approached a line of storms. By 1519, the airplane had leveled off about 24,500 ft msl and returned to a northeasterly course.
Air traffic control attempted to contact the pilot after the airplane climbed through 18,000 ft into Class A airspace, but the attempts were unsuccessful. About 1756, the airplane began a descent from 24,500 ft msl, at which point it was about 25 miles west of Green Bay, Wisconsin. The course became slightly erratic around 1758, but about 6 minutes later, the airplane resumed a northeasterly course with a steady descent of about 1,000 ft per minute. The final data point was recorded at 1817:11. The airplane impacted a cornfield about 480 ft northeast of the final recorded data point, with the impact path aligned with the final portion of the flightpath.
Aircraft Information
The airplane was not pressurized but was equipped with an onboard oxygen system comprising a 76.5-cubic ft oxygen cylinder installed below the front seats, fitted with an altitude compensating regulator. The cylinder shutoff valve was controlled by a push-pull knob on the lower instrument panel. Oxygen receptacles were located on the left and right cockpit sidewalls for the pilot and copilot, with additional receptacles in the center cabin. A pressure gauge was on the left sidewall, but there was no independent low-pressure warning.
A pulse-demand oxygen delivery module was connected to the right sidewall copilot receptacle, fitted with two nasal cannulas. First responders reported that the pilot was found wearing one. The module was set to the “F10” mode, supplying an oxygen flow rate equivalent to 10,000 ft above the sensed pressure altitude. The module had flow fault, apnea event, and low-battery warnings. The flow fault indicated if no oxygen was flowing, and the apnea event warned if no inhalation was detected within 30 seconds. Neither warning indicated that the oxygen supply was depleted. The NTSB did not evaluate the salience of these alarms in a noisy cockpit with a headset.
No record indicated when the oxygen system was last serviced or refilled. The airplane was also equipped with an autopilot, but no data about its use during the flight were available.
Meteorological Information
At 1450, National Weather Service composite radar mosaic showed a line of rain showers and thunderstorms across the airplane's flightpath, extending from near Wichita, Kansas, southeast to Tulsa, Oklahoma, and past Hot Springs, Arkansas. Individual thunderstorm cell tops were indicated from 20,000 to 24,000 ft msl.
Wreckage and Impact
After impacting the cornfield, the airplane slid about 150 ft before coming to rest. The landing gear and wing flaps were retracted. The lower fuselage was damaged from the nose to mid-cabin. Flight control continuity was confirmed. Engine examination revealed no anomalies preventing power production. Both fuel tanks were intact; about 35 gallons remained in the left tank, none in the right. The cockpit fuel selector was set to the right tank.
Examination of the oxygen system showed the cylinder intact but the regulator and relief valve fittings damaged by impact. The cylinder valve was in the ON position, and the control cable was intact. Oxygen lines were intact except for a cracked right-angle fitting at the left sidewall receptacle. A leak was identified behind the left sidewall. Metallurgical examination showed that part of the fracture surface had Teflon thread sealant embedded in the first three threads, consistent with a casting defect; the rest showed ductile dimples from overstress. The cylinder valve, regulator, and pressure gauge tested within normal parameters. The pulse-demand module also tested without anomalies.
Medical and Pathological Information
The 67-year-old male pilot had last aviation medical examination in October 2017, reporting occasional asthma symptoms treated with fluticasone/salmeterol. The aviation medical examiner found he met the Conditions AMEs Can Issue criteria for asthma. No significant issues were noted.
Autopsy performed by the Office of the Dane County Medical Examiner determined the cause of death as blunt force injuries, manner accident. The medical examiner commented that the pilot died from blunt force injuries complicating hypertensive and atherosclerotic heart disease, but also noted minimal injuries and hemorrhage suggested natural causes before the crash, though the contribution of injuries to unconsciousness or immediate death could not be excluded. The autopsy revealed an enlarged heart (530 grams), left ventricular wall thickness 1.6 cm, right ventricular wall 0.4 cm, and interventricular septum 1.6 cm, all near upper normal limits. No coronary atherosclerosis was found. Kidneys showed chronic hypertensive changes; lungs showed pulmonary hypertension with plexiform lesions.
Toxicology testing by NMS Labs detected delta-9-tetrahydrocannabinol (THC) at 0.63 ng/mL in subclavian blood; no THC metabolites. The FAA Forensic Sciences Laboratory detected loratadine and its metabolite desloratadine, but no THC or metabolites.