CEN19FA004

The pilot and passenger departed on the cross-county flight in visual meteorological conditions. Automatic dependent surveillance-broadcast (ADS-B) and GPS data indicated that, after takeoff, the airplane proceeded east and that, for most of the flight, flew at altitudes that were between 8,500 and 9,500 ft mean sea level (msl). However, as the flight progressed, the weather conditions deteriorated. Toward the end of the flight, the airplane began descending from 9,000 ft msl at a descent rate of about 700 ft per minute. The airplane then entered a descending right turn with a decreasing radius before the ADS-B and GPS data ended. The radius of the turn was initially about 4,000 ft and decreased during the next minute to about 1,000 ft by the final 1 second of the data. As the airplane continued to turn, the descent rate increased; the average rate of descent of the airplane for the final 10 seconds of the recorded ADS-B data was about 12,900 ft per minute. The airplane wreckage was distributed over a large area with airframe parts located 3,600 ft from the main wreckage location and lighter-weight items from within the airplane located more than 1 mile away. The wreckage distribution indicated that the airplane broke apart during flight and before contacting the ground. Examination of the airframe and engine revealed no anomalies consistent with a prebreakup failure or malfunction. Weather data indicated that marginal visual flight rules conditions prevailed across the area with ceilings overcast from 2,500 to 3,000 ft agl. Several weather stations immediately north and north-northeast of the accident site reported instrument flight rules (IFR) conditions to low IFR conditions, indicating ceilings of less than 1,000 ft agl and/or visibilities of less than 3 miles. No breaks in the overcast layer of clouds were reported surrounding the time of the accident, so the pilot's visual flight into IMC would have been conducive to the development of spatial disorientation. The pilot held an instrument rating, but a review of his flight logbook revealed that he had logged a total of only 2.3 hours of actual instrument flight experience, including 0.2 hour during the 3 months preceding the accident. As a result, the pilot did not likely possess the experience or recency to adequately control the airplane through the use of the instruments in IFR conditions. Thus, it is likely that the pilot experienced spatial disorientation during an encounter with IMC, which progressed into a graveyard spiral (as indicated by the tightening of the turn) and a subsequent loss of control.

The FAA Civil Aeromedical Institute's publication, "Introduction to Aviation Physiology," defines spatial disorientation as a "loss of proper bearings; state of mental confusion as to position, location, or movement relative to the position of the earth." Factors contributing to spatial disorientation include changes in acceleration, flight in IFR conditions, frequent transfer between visual flight rules and IFR conditions, and unperceived changes in aircraft attitude. The FAA's Airplane Flying Handbook (FAA-H-8083-3B) describes some hazards associated with flying when the ground or horizon are obscured. The handbook states, in part, the following: The vestibular sense (motion sensing by the inner ear) can and will confuse the pilot. Because of inertia, the sensory areas of the inner ear cannot detect slight changes in airplane attitude, nor can they accurately sense attitude changes that occur at a uniform rate over a period of time. On the other hand, false sensations are often generated, leading the pilot to believe the attitude of the airplane has changed when, in fact, it has not. These false sensations result in the pilot experiencing spatial disorientation. The FAA's Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25B) provides information concerning spatial disorientation and vestibular illusions. Regarding the "graveyard spiral" illusion, the handbook states the following: A pilot in a prolonged coordinated, constant-rate turn may experience the illusion of not turning. During the recovery to level flight, the pilot will then experience the sensation of turning in the opposite direction causing the disoriented pilot to return the aircraft to its original turn. Because an aircraft tends to lose altitude in turns unless the pilot compensates for the loss of lift, the pilot may notice a loss of altitude. The absence of any sensation of turning created the illusion of being in a level descent. The pilot may pull back on the controls in an attempt to climb or stop the descent. This action tightens the spiral and increases the loss of altitude; this illusion is referred to as a 'graveyard spiral'…. This may lead to a loss of aircraft control. On October 12, 2018, about 1608 central daylight time (CDT), a Piper PA-32RT-300, N221MC, was destroyed when it was involved in an accident near Poolville, Texas. The pilot and passenger were fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. Marginal visual meteorological conditions prevailed for the flight. The flight originated from the Sierra Blanca Regional Airport (SRR), Ruidoso, New Mexico, about 1325 CDT and was destined for Hicks Airfield (T67), Fort Worth, Texas. Automatic dependent surveillance-broadcast (ADS-B) data from the Federal Aviation Administration (FAA) and GPS data from the airplane's Garmin 696 GPS receiver showed that the airplane was on a straight ground track and at a cruise altitude between about 8,500 and 9,500ft mean sea level (msl) for most of the flight. About 1605 the airplane began descending from 9,000 ft msl. During the next 2 minutes, the airplane remained on a straight ground track at an average descent rate of 700 ft per minute. The airplane then entered a descending right turn with a decreasing radius, as shown in the figure; the radius of the turn was initially about 4,000 ft, which decreased during the next minute to about 1,000 ft in the final 1 second of data. Also, as the airplane continued to turn, the descent rate increased; the average rate of descent for the final 10 seconds of the recorded ADS-B data was about 12,900 ft per minute. The final recorded ADS-B data point was located about 900 ft west of the main wreckage location at an altitude of 4,350 ft msl. The accident site was located about 24 nautical miles west of T67. Figure. GPS data showing the final portion of the accident flight. An autopsy was performed by the Office of Chief Medical Examiner, Tarrant County Medical Examiner's District, Fort Worth, Texas. The pilot's cause of death was blunt force trauma. Toxicology testing performed at the FAA Forensic Sciences Laboratory was negative for ethanol and all tested-for substances. The weather observations surrounding the accident site indicated marginal visual flight rules conditions with ceilings overcast from 2,500 to 3,000 ft above ground level (agl). Several airport weather stations immediately north and north-northeast of the accident site reported instrument flight rules (IFR) conditions to low IFR conditions at the time of the accident. No breaks in the overcast layer of clouds were reported surrounding the time of the accident. Satellite imagery indicated the presence of nimbostratus-type clouds over the accident area, with cloud tops near 19,000 ft over the accident site. There was no record of any preflight weather briefings or flight plan being filed by the accident pilot. The recorded weather conditions at SRR about the departure time included clear skies and 10 miles of visibility, but weather observations along the route of flight indicated that the conditions deteriorated as the flight progressed. There was no record of the pilot receiving any preflight weather briefings or filing a flight plan. A review of the pilot's logbook indicated that he had 2.3 hours of actual instrument flight experience and 43 hours of simulated instrument flight experience. Between June 8, 2018, and the last entry dated September 28, 2018, the pilot logged 0.2 hour of actual instrument flight and no simulated instrument flight. The airplane wreckage was distributed in a northeast direction for about 3,600 ft. The main wreckage consisted of most of the fuselage, the inboard right wing, and the airplane's engine. The elevation at the main wreckage location was about 1,250 ft msl. The left wing was found about 500 ft and 320° from the main wreckage. The airplane's left fiberglass wing tip was located about 3,500 ft and 58° from themain wreckage. Various other airplane parts were found distributed in a triangle-shaped pattern formed by the location of the main wreckage, the left wing, and the left wing tip. Additional debris determined to be items from within the airplane came to rest about 6,500 ft and 62° from the main wreckage. The right side of the horizontal stabilator failed in downward bending, and the left side of the horizontal stabilator failed in upward bending. The left wing was located at the beginning of the wreckage path. The airplane's vacuum pump was damaged, but no preimpact defects were noted. The gyroscope cores from two vacuum-operated instruments were found and disassembled. In both cases, the spinning portion of the gyroscopes and the gyroscope housings had evidence of rotational scoring, indicating that the gyroscopes were spinning upon impact. Examination of the airframe and engine revealed no anomalies consistent with a prebreakup failure or malfunction.