Piper PA46-500TP N241PM

The pilot departed about 1721 central daylight time (all times CDT unless otherwise noted) on an instrument flight rules cross-country flight with one passenger and two dogs. After departure, the airplane turned onto a northwesterly track toward the destination. The pilot requested flight level (FL) 280 and, at 1841, reported to air traffic control (ATC) that his satellite weather radar was not functioning; he later asked for assistance navigating through weather. At 1908, he reported light chop over the previous 40 miles but that the flight was currently smooth. At 1944, ATC instructed the pilot to descend to FL 240 and the pilot then checked in with a new ATC center on his route and reported descending with moderate chop. ATC responded by instructing the pilot to descend at his discretion to 17,000 ft msl (all altitudes in msl unless otherwise noted). The airplane reached FL 240 (the previously instructed altitude) at 1949, where it stayed for less than a minute before continuing its descent. The first portion of this descent was at a rate of 2,000 ft/min before slowing to about 1,000 ft/min. At 1954, while the airplane was descending through 20,000 ft, ATC instructed the pilot to descend at his discretion to 6,000 ft. The airplane’s rate of descent increased to more than 3,000 ft/min, and the airspeed markedly increased from 170 kts to over 200 kts, exceeding the airplane’s maximum operation limit of 187 kts calibrated airspeed; the airplane was at risk of structural damage when exceeding this limitation. Data showed that the airplane’s descent then arrested about 18,000 ft (which ADS-B data recorded as the selected altitude) and it began a small climb as the airplane’s airspeed began to slow below 170 kts. At the same time, the airplane began a slight right turn off of its original course that was consistent with the airplane no longer under autopilot control. Twenty seconds later, the airplane began to rapidly descend in a tightening right turn while the calibrated airspeed rapidly increased, again surpassing the maximum operation limit. ATC simultaneously lost communication and radar contact with the airplane at 7,800 ft msl. The controller attempted to contact the pilot with no response. ATC then issued an alert notification (ALNOT) and a search began. Weather radar imagery showed the airplane encountering light intensity echoes as it descended from 24,000 ft consistent with instrument meteorological conditions. Based on the temperature profile, the cloud droplets and precipitation were in a supercooled liquid state that put the airplane at risk of structural icing. However, the airplane was equipped with deicing boots, and the performance study data showed no increase in the airplane’s drag, which was indicative of ice accumulation, before the airplane’s departure from straight flight. The airplane sustained structural damage during at least one of the airspeed exceedances and eventually broke apart in flight. The wing spar box signatures and fuselage witness marks from contact with the wing leading edge de-ice boots suggested positive wing loading before the in-flight breakup. The left horizontal stabilizer, vertical stabilizer, rudder, elevator, right aileron, right flap, and the outboard portion of the right wing were not located at the accident site and likely separated as a result of the in-flight breakup. The pilot would not have had out-of-cockpit visual reference for the majority of the end of flight. The investigation considered the possibility that the pilot experienced spatial disorientation after taking control of the airplane from the autopilot during the descent. Although the tightening turn is consistent with a loss of control due to spatial disorientation, the pilot had over 1,300 hours of actual instrument flight experience and likely would have been aware of the possibility of such illusory effects. Additionally, the lowest cloud bases were about 10,000 ft which would have given the pilot a small amount of time to regain orientation if he had become disoriented. It is possible that the airplane’s deviation from the intended track (indicative of the airplane no longer under autopilot control), whether pilot induced or not, was the result of a structural failure. Analysis of weather sounding data also indicated strong vertical wind shear between 13,000 ft and 16,000 ft and a high possibility of moderate or greater turbulence within those altitudes. Accordingly, the investigation also considered the possibility that the airspeed exceedances during the descent, combined with the moderate and greater turbulence forecast for the area just below the airplane’s flight path, resulted in structural damage to the airplane that rendered it uncontrollable. Given that the loss of control happened within about 20 seconds from the time the airplane deviated from its flight path (no longer under autopilot control) and that the pilot (who was experienced in actual instrument conditions) was not able to recover airplane control, the airplane likely sustained airframe damage from the airspeed exceedances during the descent that prevented the pilot or autopilot from maintaining control. A medical review revealed the pilot’s coronary artery disease was associated with some increased risk of an impairing or incapacitating cardiovascular event such as chest pain, abnormal heartbeat, or heart attack. Although such an event does not leave reliable autopsy evidence if it occurs immediately before death, there is no autopsy evidence that such an event occurred. Additionally, the pilot’s postmortem toxicology results indicate that he had used phentermine. The phentermine results in postmortem urine and tissue provided no clear evidence that the pilot was experiencing significant associated impairing effects at the time of the accident.

Quoted verbatim from the NTSB record.