CEN21LA030

The instrument-rated pilot had recently purchased the accident airplane, which was not equipped for icing conditions, and was in the process of flying it back to his home base. During the first flight after purchase, he flew at 11,000 ft and was reportedly sick during and after the flight. The pilot was sick and miserable all weekend with symptoms to include queasiness, fatigue, dizziness, and a general malaise. Following a discussion with friends regarding the forecast icing conditions along the route, the pilot departed for his destination airport. While en route, the pilot requested from air traffic control permission to divert to another airport “for fuel considerations” and stated that he had been flying in instrument meteorological conditions (IMC) for a while. The controller directed the pilot to an instrument approach fix but the pilot did not intercept the fix in time, so the controller rerouted him to the east to attempt the approach from the other side. At this time, the pilot would have been in icing conditions, but he did not express concern to the controller. During the approach, the pilot stated that he was experiencing “freezing rain”, but he continued the approach. Based on the airplane’s flightpath it is likely that the autopilot was engaged. The airplane’s flight track revealed that after the airplane passed the final approach fix the airspeed decreased below 50 knots and the airplane made a sharp left descending turn. The airplane impacted the ground behind a residence and a postimpact fire consumed a majority of the fuselage. Available weather data revealed that the airplane was in IMC, icing conditions, and likely encountered supercooled liquid droplets during the flight. These conditions would have created an environment favorable for structural icing. A review of the pilot’s flight planning account revealed that he had requested a weather briefing and would have had access to the most accurate and updated weather information. The pilot reported to his girlfriend that he “wanted to beat the weather” on the day of the accident. This statement is consistent with the pilot’s self-induced pressure to complete the flight due to the incoming adverse weather conditions. A postaccident examination of the airplane revealed thick chunks of ice on and near the leading edges of the airplane that were consistent with structural ice. While the pilot reported an autopilot issue, it is likely that the airplane had accumulated enough structural ice that the autopilot had difficulty functioning properly. Based on the evidence, the accident is consistent with the pilot not able to maintain control of the airplane. The examination revealed that the cabin air heat exchanger had preaccident cracking, which allowed exhausts gases to mix with the cabin air. Based on the condition of the exhaust system and heat exchanger, it is likely that the system was not adequately inspected during the last annual inspection. The pilot’s toxicology revealed anelevated carboxyhemoglobin level. It is likely that the pilot was impaired by the effects of carbon monoxide poisoning and this impairment contributed to the pilot’s overall confusion, willingness to continue flight in icing conditions, and to the circumstances of the accident.

In September 2017, the NTSB issued Safety Alert SA-069 (https://www.ntsb.gov/Advocacy/safety-alerts/Documents/SA-069.pdf) warning pilots of the dangers of carbon monoxide poisoning. The alert stated in part: pilots often overlook or dismiss the onset of symptoms and don’t connect them with the possibility of exposure to CO. Continued exposure increases risks to pilots, including impaired judgment and decreased ability to control the airplane and, eventually, incapacitation and death. As mentioned in the safety alert, the FAA has published two advisory circulars (AC 20-32B and AC 43-13-1B), Special Airworthiness Information Bulletin CE-10-19R1, and an informational brochure about the causes of and methods to detect and avoid carbon monoxide poisoning. The pilot had purchased the airplane in Nebraska about 3 days before the accident. The airplane was not equipped with anti-icing or de-icing capabilities. There were no carbon monoxide detectors installed in the airplane. The airplane was topped off with fuel on the morning of the accident. According to the Cessna 210 Owner’s Manual, with full fuel tanks, the airplane endurance is more than 5 hours, and the range is more than 800 statute miles. The airplane’s maintenance logbook showed the exhaust system had been inspected during the last annual inspection (about 7 flight hours before the accident flight), and the airplane was determined to be in an airworthy condition. According to the Cessna 210 maintenance manual, “inspection of the exhaust system should be thorough because the cabin heating system uses air heated by the heat exchangers of the exhaust system. Since exhaust systems of this type are subject to burning, cracking, and general deterioration from alternate thermal stresses and vibration, inspection is important and should be accomplished every 100 hours of operation. In addition, an inspection should be performed any time exhaust fumes are detected in the cabin.” On October 26, 2020, at 1558 central daylight time (CDT), a Cessna 210 airplane, N9622T, was destroyed when it was involved in an accident near Lubbock, Texas. The pilot was fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The airplane was on an instrument flight rules (IFR) flight plan from Belen Regional Airport (BRG), Belen, New Mexico, to Corsicana Municipal Airport (CRS), Corsicana, Texas, but had diverted to Lubbock Preston Smith International Airport (LBB), Lubbock, Texas. A review of the air traffic control (ATC) recordings revealed that the pilot had difficulty communicating with controllers. During the first 2 hours of the flight, he experienced icing conditions and requested lower altitudes multiple times. The ATC recordings and automatic dependent surveillance broadcast (ADS-B) data revealed at 1454 CDT the pilot requested to divert to LBB “for fuel considerations.” At 1523, CDT the pilot reported that he had been in IMC for a while. The pilot wasinstructed to setup for the RNAV (GPS) Y instrument approach to runway 35L. During the approach, the pilot was unsure of which instrument approach to expect and was not in position to intercept the final approach course, so the controller vectored the pilot to the east to conduct the same approach but with a different initial approach fix. When queried by the controller, the pilot reported that he was experiencing icing and was in freezing rain. After the airplane crossed the intermediate fix, ZOVOC, and turned inbound, the groundspeed gradually decreased from about 80 kts to about 50 kts. The pilot reported to the controller that the airplane experienced an autopilot issue. Then after the airplane crossed the final approach fix, UFACI, about 4,700 ft mean sea level (msl) and 48 kts groundspeed, it made a left turn south-southeast and descended. The flight track indicated that the airplane continued to descend then made a sharp left turn before the data ended. There were no further communications from the pilot. Figure 1. Accident flight track with approach fixes and accident site labeled. Several witnesses observed the airplane appear to enter the beginning of a loop, then quickly descend to the ground. The airplane impacted the ground near a residence and a postcrash fire ensued. Toxicology testing performed by the FAA’s Forensic Services Laboratory on the pilot’s cavity blood and urine detected amlodipine and phentermine. Also, a carboxyhemoglobin level of 13% was detected in the cavity blood. Carbon monoxide (CO) is an odorless, tasteless, colorless, nonirritating gas formed by combustion as in a piston engine. CO binds to hemoglobin with much greater affinity than oxygen, forming carboxyhemoglobin; elevated levels result in impaired oxygen transport and utilization. Nonsmokers may normally have up to 3 percent carboxyhemoglobin in their blood; heavy smokers may have levels of 10 to 15 percent. This pilot was not a smoker. Acutely, lower levels of CO may cause vague symptoms like headache, nausea and mild confusion; increasing levels (40 percent and above) lead to profound confusion, seizures, loss of consciousness, and death. Amlodipine is a prescription blood pressure medication and is not considered impairing. Phentermine is a prescription medication intended for the short-term treatment of obesity. It is a Schedule IV controlled substance because it is related to amphetamines and has the potential for abuse. It carries this warning as a result, “Phentermine may impair the ability of the patient to engage in potentially hazardous activities such as operating machinery or driving a motor vehicle; the patient should therefore be cautioned accordingly.” Archived ForeFlight information indicated that the accident pilot requested weather information for a planned flight at 11,000 ft at 1246 CDT with a planned departure of 1255 CDT. The 1246 CDT weather briefing information contained weather information valid at 1246 CDT including currentMETARs valid along the route of flight, PIREPs, AIRMETs, center weather advisory, a surface analysis chart, a graphical forecast for aviation, terminal aerodrome forecasts, turbulence cross section information, and the winds aloft information. According to ForeFlight, the pilot accessed convective weather imagery at 0728 and 0758 CDT. There is no record that the pilot requested or received any other weather information before or during the accident flight. The precipitation in the accident region was very light, and light accumulating freezing drizzle was reported at the surface. The accident site and surrounding area were covered by a center weather advisory and AIRMETs that warned of freezing rain, freezing drizzle, and light snow conditions along with moderate or greater icing conditions. A Lubbock Police officer in the area observed the accident and stated that the weather was cloudy and icy with mist. Three days before the accident flight, the pilot flew the airplane from Nebraska to Belen, New Mexico. During the flight he climbed to 11,000 ft to get above a layer of smoke. When he arrived in New Mexico he told his girlfriend that he felt sick during the flight. She reported to the pilot’s friend that the pilot was sick and miserable all weekend, and that, he was queasy, fatigued, dizzy, and a general malaise. On the day of the accident the pilot told her that he wanted to beat the weather. The pilot’s flight logbooks were not found during the course of the investigation; therefore, the pilot’s recent and total IFR flight experience could not be determined. Close friends of the pilot stated that he was not a smoker and had not smoked for several years. The responding Federal Aviation Administration (FAA) inspectors reported that the airplane impacted a residential area about 200 yards from the final recorded ADS-B point. A postimpact fire consumed most of the fuselage and the inboard sections of each wing. The inspectors found numerous chunks of ice in the wreckage near the wings, and ice still attached to some of the airplane’s leading-edge surfaces. The ice chunks were concave shaped and featured a smooth surface on the inside of the curve. The ice ranged in size from 1 to 2 inches thick. Figure 2. Two of the ice chunks from the leading edge of the wings. A postaccident examination of the airplane revealed that the cabin air heat exchanger contained cracks in the metal barrier that separated the engine exhaust gas and the cabin air. The branching cracks exhibited fracture faces with corrosion and deposits on the surface consistent with the cracks being preexisting to the accident. Examination of the airplane did not reveal any other mechanical malfunctions or anomalies that would have precluded normal operation.