Piper PA-32RT-300T N39965

The pilot and passenger departed on an instrument flight rules flight with a cruise altitude of 12,000 ft. About 1 hour after takeoff, the air traffic controller advised the pilot of an area of moderate to extreme precipitation along the airplane's route of flight, and the pilot replied that he observed the same on his "radar." (The airplane was not equipped with airborne weather radar, rather the pilot was likely referring to ground-based weather radar data that he was viewing on a tablet computer.) The controller cleared the pilot to deviate 30 degrees left of course. The pilot did not acknowledge the clearance and continued on a southeasterly course for about 10 minutes. He then initiated a 180-degree left turn during which the airplane climbed to about 12,600 ft and then descended to about 9,700 ft. Overlaying the airplane's flight track on weather radar data showed that, during the 180-degree turn, the airplane passed through an area of moderate to very heavy rain with the possibility of hail, severe turbulence, and lightning. Observing the airplane's change in heading and altitude, the controller asked the pilot if he was attempting to deviate around weather and if he required assistance. The pilot replied that he was "going a little bit to the left to the weather." The controller instructed the pilot to advise when he was established back on course, and the pilot acknowledged. Over the next 4 minutes, the airplane continued on a northwesterly heading and descended to about 9,000 ft as it exited the area of precipitation. During this time, the controller contacted the pilot four separate times, advising him that the airplane was below its assigned altitude and asking if he needed assistance. The pilot did not respond to the first inquiry. His responses to the second and third inquiries were slurred, and his speech rate was markedly decreased. He stated that he needed assistance and that he was trying to get back to the assigned altitude. The pilot did not respond to the fourth inquiry. The airplane then began a gradual 360-degree right turn, during which its altitude varied between 9,100 and 9,900 ft. The controller again asked the pilot his intentions, and the pilot stated that he was climbing back to 12,000 ft and heading direct to his destination airport. When queried as to the reason for the airplane's descent, the pilot replied "just a lot of weather here I'm working on it." The airplane continued turning right for about 2 minutes, then entered a steep right turn during which it descended about 2,500 ft in less than 30 seconds. During the following 5 minutes, the controller repeatedly asked the pilot if he required assistance, instructed him to climb, and assigned the airplane a heading of 270 degrees; however, the airplane climbed slowly on a heading of about 210 degrees. The controller advised the pilot that if he continued on that heading, the airplane would encounter moderate precipitation. The pilot's response was largely unintelligible. ATC again asked the pilot to verify the airplane's heading, and the pilot responded in a confused manner, but the airplane continued on its heading of about 210 degrees. No further transmissions were received from the accident airplane. About 1 minute later, the airplane turned south, continued to climb, and entered an area of light to moderate precipitation. The flight continued for about 8 minutes, conducting a series of turns to the right and left before it reached an altitude of about 12,100 ft, then entered a rapid descent. Radar contact was lost shortly thereafter. Postaccident examination of the airframe, engine, and flight instruments revealed no evidence of preimpact anomalies, and there was no evidence of an in-flight breakup. No medical issues were identified with the pilot that may have contributed to the accident, and toxicological testing was negative for impairing substances and did not suggest carbon monoxide poisoning. The airplane was traveling at 12,000 ft for a portion of the flight, an altitude at which the use of supplemental oxygen is not required. While this does not preclude the possibility of a pilot developing hypoxia at that altitude, the airplane spent about 20 minutes below 10,000 feet, and the pilot's performance did not appear to improve during that time. Therefore, it is unlikely that the pilot was experiencing hypoxia. It could not be determined why the pilot was unable to maintain control of the airplane or why he did not request assistance from the controller. The extent to which the pilot had familiarized himself with the weather conditions along the route of flight before takeoff could not be determined, as there was no record of a weather briefing from an official, access-controlled source. However, the pilot indicated to the controller that he had "radar" in the cockpit, and a portable ADS-B receiver and tablet computer were found in the wreckage, suggesting that the pilot was receiving weather information during the flight, to include Next Generation Radar (NEXRAD) and significant weather advisories. Due to latencies inherent in the process of detecting weather at a ground site, compiling a mosaic image, and subsequently delivering that data to the cockpit, NEXRAD is not an accurate depiction of actual weather conditions and should not be used for tactical weather avoidance. The pilot's comment to ATC that "[my weather display is] a little later than yours" likely indicated that the pilot was aware of these limitations. However, it is likely that, based on the pilot's use of the word "radar," the controller assumed that the airplane was equipped with airborne weather radar, which would have provided real-time information to the pilot that could be used in tactical weather avoidance. Although they discussed the weather conditions, the pilot did not explicitly state, nor did the controller ask, what kind of weather information he was receiving. This may have led the controller to believe that the pilot was able to "pick through" the weather with real-time data. The pilot's inability to maintain altitude and heading likely alerted the controller that the pilot was experiencing a problem, and the controller subsequently asked the pilot a total of eight times over a period of about 15 minutes if he required assistance. However, despite apparently recognizing that the pilot was having difficulties, the controller failed to notify his supervisor of the situation as required. The controller also failed to ask specific questions to fully understand the difficulties the pilot was experiencing, and finally, he did not declare an emergency on behalf of the pilot, which would have ensured that the airplane was given priority handling. Further, the controller's supervisor was not performing other duties during the time that the controller was providing services to the airplane and should have been engaged in the situation. Although she was sitting only a few feet from the controller, she did not become aware of what was happening until another supervisor from a different area called and asked her what was going on with the airplane. Even then, the supervisor only monitored the situation momentarily before returning to her desk. Despite the shortcomings of air traffic control services provided to the pilot, the extent to which those services may have contributed to the outcome of the flight could not be determined as it is unknown how the pilot would have responded to any actions taken by the controllers.  

Quoted verbatim from the NTSB record.