Piper PA34 N593MS

The flight instructor picked up the private pilot and passenger for a cross-country flight. The instructor requested visual flight rules (VFR) flight following services from air traffic control (ATC) and indicated a planned climb to 8,500 ft mean sea level (msl); however, the airplane continued to climb past that altitude. During the climb, the instructor indicated to the ATC controller, in separate transmissions, that he was climbing to reach "VFR on-top," that he was experiencing problems with an "unreliable" attitude indicator, and that the airplane was "in and out of IMC [instrument meteorological conditions]." Based on weather sounding and satellite imagery, it is likely that the airplane was operating in IMC above 4,100 ft. About 20 minutes after the airplane departed, the controller declared an emergency on behalf of the pilot and provided multiple radar vectors for the airplane to return to visual meteorological conditions (VMC); however, the airplane's radar track showed that the airplane continued climbing to 19,400 ft msl before it entered a series of figure-eight turns followed by a steep, turning descent. A witness stated that the airplane sounded "as if it were a stunt plane doing spins (pitch changing)" and then heard a "pop" and saw large pieces of the airplane descending from the overcast sky. Examination of the recovered portions of the airplane revealed no evidence of preimpact mechanical anomalies and a wreckage distribution consistent with an in-flight breakup. Both the instructor and the private pilot had low levels of ethanol in cavity blood but none in vitreous (instructor) or urine (private pilot). The absence of ethanol in the second specimen indicates it is likely the ethanol was not from ingestion and therefore it did not contribute to the accident circumstances. The private pilot also had evidence of use of morphine, an impairing opioid. However, the decision-making on this flight, including the route and response to weather conditions, was most likely performed by the instructor. Therefore, it is unlikely that effects from low levels of morphine in the private pilot contributed to the accident circumstances. The instructor demonstrated several lapses in judgment associated with conducting the flight. Specifically, the instructor did not appear to recognize the significance of widespread ceilings along his route of flight and planned a cruise altitude that took him into instrument conditions. The instructor likely did not carry supplemental oxygen onboard the nonpressurized airplane and continued to climb the airplane to altitudes that required the use of oxygen; without oxygen he risked becoming susceptible to the effects of hypoxia. Further, another pilot who had flown the accident airplane before the accident flight stated that the airplane had a known problem with the directional gyro, yet the instructor flew the airplane in instrument conditions; based on the instructor's failure to follow the controllers' directional instructions, it is likely the directional gyro was still not working. Lastly, review of the instructor's logbook and an interview with another flight instructor indicated that the instructor was likely not instrument current, so his ability to safely maneuver the airplane in the clouds that were prevalent during the flight would have been negatively impacted by the broken gyro and his lack of currency. In summary, the instructor's decision to continue the flight in instrument conditions with a known flight instrument anomaly greatly increased his workload and likely resulted in his eventual loss of airplane control due to spatial disorientation. The rapidly descending turn (graveyard spiral) depicted on radar and the in-flight breakup due to overstress during the ensuing uncontrolled descent were consistent with the known effects of spatial disorientation. Further, the airplane had been operating above 16,000 ft msl for more than 10 minutes at the time of the upset; there was no evidence that the airplane was equipped with supplemental oxygen. Therefore, the instructor was operating the airplane above altitudes in which supplemental oxygen is required, and without it, his performance and decision-making would have likely been degraded to some extent due to hypoxia. The flight's erratic flight track away from the intended destination and the instructor's inability to successfully maneuver the airplane in response to ATC instructions that he acknowledged are consistent with the effects of hypoxia.

Quoted verbatim from the NTSB record.