CEN18FA144

The pilot's failure to obtain an updated weather briefing before the flight and his subsequent loss of airplane control due to spatial disorientation while maneuvering in instrument meteorological conditions during a diversion to an alternate airport after encountering forecast icing conditions.

The private pilot was conducting a personal, cross-country flight with one passenger onboard. According to air traffic control (ATC) communications and radar data, while en route to the destination airport about 5,425 ft mean sea level, the pilot reported to ATC that the airplane was accumulating ice, and he requested to divert to the nearest airport. However, due to the overcast cloud layer at 200 ft above ground level (agl) at the nearest airport, the pilot chose to attempt an instrument landing system (ILS) approach into another airport with a slightly higher overcast cloud layer of 500 ft agl. During the descent to intercept the localizer for the ILS approach, the pilot flew through the localizer path, and he did not realize it until the controller notified him that he had done so. The pilot subsequently requested additional vectors to attempt to intercept the localizer again, and the controller instructed the pilot to turn left. The airplane subsequently turned left toward the north. About 39 seconds into the turn, the airplane began to descend, and the airspeed increased. About 10 seconds later, the left turn tightened, and the airplane began to spiral until the radar data ended. The airplane subsequently impacted the ground in a steep, nose-low, wings-level attitude. A review of weather information current at the time of the flight revealed that the airplane likely encountered instrument meteorological conditions (IMC) about 500 ft agl on the initial climbout from the departure airport and remained in IMC and conditions favorable to icing for the rest of the flight. The airplane likely encountered some turbulence along the flight route in the cloud cover and would have had to climb above 10,400 ft msl to escape the IMC and icing conditions. Super-cooled liquid droplets (SLD) and icing conditions were likely present along the flight route throughout the flight. Before the flight, a forecast icing potential (FIP) indicated that light-to-moderate intensity icing existed near the accident site, and a current icing potential product indicated that SLD existed near the accident site; this information would have been available to the pilot before the accident flight departed. The pilot received a weather briefing via the ForeFlight application on his mobile device about 10 hours before the accident flight. At that time, the forecast showed cloud cover, snow showers, and instrument flight rules conditions. Since the AIRMET received in the weather briefing expired at 0500 the pilot should have requested an updated briefing with the valid AIRMET. In the time between the weather briefing and the accident, an AIRMET was issued for moderate icing, IFR/mountain obscuration, and low-level turbulence, and was valid until 1100. An updated AIRMET advisory was recorded via the flight plan identification number less than 2 hours before departure. No records were found indicating whether the pilot retrieved any other weather information before or during the flight. Therefore, although the pilot had sufficient weather forecast information available to him before departure to have known about the existing icing conditions along the flight route, the investigation could not determine whether he received all of the pertinent information before the flight. Although the pilot reported that the airplane had accumulated ice, the investigation could not determine if the airplane was significantly affected by structural icing during the approach. The airplane was not equipped with an anti-icing or deicing system, which prohibited the pilot from flying into known icing conditions per Title 14 Code of Federal Regulations Section 91.527, "Operating in Icing Conditions." Although postaccident examination of the wreckage was limited due to postimpact fire damage, the examinations of the airframe and engine did not reveal evidence of any preaccident mechanical malfunctions or anomalies that would have precluded normal operation. The examination revealed that the Cirrus Airframe Parachute System (CAPS) handle remained in its holder, and that its safety pin, which was supposed to be removed before flight, remained installed. The CAPS was found deployed, and the CAPS solid rocket propellant was expended. All evidence revealed that the CAPS was not activated in flight but rather that it deployed due to impact forces and thermal exposure. The autopsy of the pilot revealed that he had heart disease; however, this would not have affected his decision-making, his ability to identify and respond to icing on the plane, or his ability to fly the airplane in IMC; therefore, his heart disease did not contribute to the accident. Although toxicology testing detected ethanol in the pilot's liver tissue, no ethanol was found in his muscle tissue. Given that, after absorption, ethanol is uniformly distributed throughout all tissue and body fluids, it is likely that the ethanol detected in the liver occurred postmortem and did not contribute to the accident. The toxicology testing also detected two impairing psychoactive substances, diphenhydramine and clonazepam, in tissue specimens. These drugs alone or in combination could have affected the pilot's decision-making and/or slowed his detection of potential hazards and his reaction to them. However, antemortem levels of these two drugs could have been low enough to not have affected him, but, because antemortem levels cannot be calculated from tissue levels, it could not be determined whether effects from the pilot's use of diphenhydramine and clonazepam contributed to the accident. The radar data showed that the airplane was flying a relatively smooth and consistent flightpath with altitude and heading changes that were indicative of the pilot using the autopilot for a majority of the flight, until the final turn after flying through the localizer course. The pilot's failure to recognize that he had not intercepted the localizer is consistent with his failure to appropriately configure the avionics for the approach or with his attention being diverted from navigational tasks due to his workload while trying to conduct the approach. Conditions conducive to the development of spatial disorientation, including restricted visibility and IMC while maneuvering, existed. Further, the accident circumstances, including the spiraling radar track data and the subsequent high-velocity impact were consistent with the known effects of spatial disorientation. Therefore, the airplane's entry into a descending left turn while the pilot was being vectored back toward the localizer course, which subsequently tightened, was likely due to the pilot experiencing the effects of spatial disorientation due to a vestibular illusion referred to as a "graveyard spiral," which can occur when an airplane returns to level flight following a prolonged bank turn. The spatial disorientation resulted in the pilot's loss of airplane control and a high-velocity impact with terrain.

A review of the pilot's logbook revealed that he accumulated 70 hours of total flight experience from 1980 to 1985. He did not log any additional flight time until 2011. He first flew the accident airplane on January 31, 2014, and then exclusively logged flights in the accident airplane from April 9, 2014, until the accident date. The pilot's flight instructor stated that he had flown with the pilot six times in the 6 months before the accident. Four of the flights were conducted for the purpose of maintaining instrument currency and proficiency. Their most recent flight was on November 30, 2017, during which the pilot completed ILS and GPS approaches in simulated IMC. The pilot's logbooks showed that he had completed the recent instrument experience requirements in accordance with 14 CFR Section 61.57, "Recent flight experience: Pilot in command." Mount Nittany Medical Center, State College, Pennsylvania, conducted an autopsy of the pilot. The autopsy report concluded that the cause of death was "blunt force trauma." The examination was limited due to the extent of damage to the pilot's body as a result of the accident. However, the autopsy was able to determine that the pilot had mild-to-moderate atherosclerotic coronary artery disease with 50% stenosis of the left coronary artery and 30% stenosis of the left circumflex coronary artery. The examination of the remaining available cardiac tissue was unremarkable. Toxicology testing performed by the laboratory at FAA Forensic Sciences identified the following: 10 mg/dL ethanol in liver tissue but no ethanol in the muscle tissue, diphenhydramine in liver and muscle tissue, amlodipine in kidney tissue, atenolol in kidney and heart tissue, 0.039 µg/mL 7-amino-clonazepam in kidney tissue, and 0.026 µg/mL 7-amino-clonazepam in lung tissue. Ethanol is an intoxicant, which, after absorption, is uniformly distributed throughout all tissue and body fluids. It may also be produced in postmortem tissue by microbial action. Diphenhydramine is a sedating antihistamine used to treat allergy symptoms and as a sleep aid. It is available over the counter under the names Benadryl and Unisom. In a driving simulator study, a single 50 mg dose of diphenhydramine impaired driving ability more than a blood alcohol concentration of 0.100%. Diphenhydramine carries the following U.S. Food and Drug Administration (FDA) warning: "may impair mental and/or physical ability required for the performance of potentially hazardous tasks (e.g., driving, operating heavy machinery)." Compared to other antihistamines, diphenhydramine causes marked sedation, which is the rationale for its use as a sleep aid. Altered mood and impaired cognitive and psychomotor performance may also be observed. Amlodipine and atenolol are nonimpairing blood pressure medications, and the pilot had reported them to the FAA. According to records obtained from the pilot's primary care physician, at the time of the accident, the pilot had been prescribed both atenolol and amlodipine to control his hypertension. Clonazepam, the parent drug that is metabolized into 7-amino-clonazepam (an inactive metabolite) is a sedating benzodiazepine used to treat panic and anxiety disorders and certain kinds of seizures. Clonazepam carries the following FDA warning: "Since clonazepam produces central nervous system (CNS) depression, patients receiving this drug should be cautioned against engaging in hazardous occupations requiring mental alertness, such as operating machinery or driving a motor vehicle. They should also be warned about the concomitant use of alcohol or other CNS-depressant drugs during clonazepam therapy." No records were found regarding a prescription for clonazepam or any disorder that would have required its use. General The altitude indicating system and transponder, which were most recently tested in accordance with the requirements of 14 CFR Sections 91.411 and 91.413, "Altimeter system and altitude reporting equipment tests and inspections" and "ATC transponder tests and inspections," respectively, on September 26, 2017. The airplane was not equipped with an anti-icing or deicing system, thus it was not equipped for flight in icing conditions. The pilot had the ForeFlight application on a mobile device, which provided instrument approach plates; paper approach plates were found at the accident site. The cockpit instrumentation included an airspeed indicator, attitude indicator, altimeter and a turn coordinator, vertical speed indicator, Garmin mechanical course deviation indicator, and Sandel SN3308 electronic horizontal situation indicator. The airplane was also equipped with an S-TEC 55X autopilot, a Garmin GTX345 transponder, dual Garmin GNS 430 units, and an ARNAV ICDS-2000 multifunction display (MFD) with an engine monitoring module (EMM-35) that displayed engine data. The ARNAV unit displayed, in part, navigational waypoints, course line, and ground speed and had a separate database, which displayed terrain elevations based on position. The Garmin GNS 430 was approved for IFR operations; however, the ARNAV MFD was for reference only and was not certified for flight in IMC. Cirrus Airframe Parachute System (CAPS) The airplane was equipped with a Ballistic Recovery Systems ballistic recovery parachute system. According to Cirrus, the CAPS will lower the airplane's entire airframe to the ground when all alternatives to land the airplane have been exhausted. The CAPS consisted of a parachute, a solid-propellant rocket to deploy the parachute, a rocket activation handle, and a Kevlar harness embedded within the fuselage structure. The pilot could activate the system by pulling on a T-handle mounted on the cockpit ceiling above the pilot's right shoulder, which in turn activated the firing pin mechanism that then ignited the solid-propellant rocket in the parachute enclosure. In the airplane's Pilot's Operating Handbook "Normal Procedures, Preflight Walk-Around" checklist, item 1 states, "CAPS Handle…Pin Removed." In the "Before Starting Engine" checklist, item 4 states, "Verify CAPS handle safety pin is removed." In the "Before Takeoff" checklist, item 2 states, "CAPS Handle…Verify Pin Removed." On April 19, 2018, at 0843 eastern daylight time, a Cirrus SR22 airplane, N451TD, impacted terrain near Williamsburg, Pennsylvania. The private pilot and one passenger were fatally injured. The airplane was destroyed, and a postimpact fire consumed most of the wreckage. The airplane was registered to CPD-JJD, LLC, and operated by the pilot as a Title 14 Code of Federal Regulations (CFR) Part 91 personal flight. Instrument meteorological conditions (IMC) prevailed along the flight route about the time of the accident, and an instrument flight rules (IFR) flight plan had been filed. The airplane departed Lancaster Airport (LNS), Lancaster, Pennsylvania, at 0734 and was initially en route to South Bend International Airport (SBN), South Bend, Indiana, but the pilot chose to divert toward Altoona-Blair County Airport (AOO), Altoona, Pennsylvania. The pilot received a weather briefing the night before the accident and filed a flight plan. Refer to the Meteorological Information section for more information. A review of air traffic control (ATC) communications and radar data provided by the Federal Aviation Administration (FAA) revealed that, about 0828, while the airplane was en route to SBN on a 284° heading and about 5,425 ft mean sea level (msl), the pilot contacted an approach controller at John Murtha Johnstown-Cambria County Airport (JST), Johnstown, Pennsylvania, and requested to divert to JST (18 miles southwest of the airplane's position) due to ice accumulation on the airplane. The controller advised the pilot that the clouds at JST were overcast at 200 ft above ground level (agl) and that the clouds at AOO (30 miles southeast of the airplane's position) were overcast at 500 ft agl. About 0831, the