Nashville-John C. Tune

Inbound from Nashville-John C. Tune Airport, the twin engine airplane crashed in a wooded area located short of runway 36 at Slidell Airport, bursting into flames. The pilot, sole on board, was seriously injured.

While on an instructional flight in icing and instrument meteorological conditions (IMC), the pilots indicated that they were having instrumentation difficulties to air traffic control. They initially reported a problem with the autopilot, then a navigational issue, which they later indicated were resolved, and finally they reported it was a problem with the left side attitude indicator. After air traffic control cleared them to their destination, the airplane entered a descending left turn, which continued into a 360° descending turn. An inflight breakup resulted, with the wreckage being scattered over 7,000 ft of wooded terrain. Examination of the engines revealed there were no anomalies that would have precluded normal operation prior to the accident. Control cable continuity was established from the flight controls in the cockpit to all flight control surfaces through multiple overload failures. The pitot-static system was examined, and no blockages were noted. Since there was rotational scoring noted on the vertical gyro and the directional gyro, it’s likely they were operating at the time of the accident. Furthermore, the left side attitude indicator examination revealed that there were no anomalies with the instrument. Examination of the deice valves for the deicing boots revealed that the left wing deice valve did not operate. Corrosion was visible in all three valves and it could not be determined if the corrosion was a result of postimpact environmental exposure. Furthermore, since the cockpit switch positions were compromised in the accident, it could not be determined if the pilots were operating the deicing system at the time of the accident. However, most of the pilot reports (PIREPs) in the area indicated light icing and the airplane performed a 6,000 ft per minute climb just before the loss of control. Given this information, it is unlikely the icing conditions made the airplane uncontrollable. A review of the pilots’ flight experience revealed that the pilot in the left seat did not hold a type rating for the accident airplane model but was scheduled to attend flight training to obtain such a type rating. The pilot in the right seat, who also held a flight instructor certificate, did hold a type rating for the airplane. Given that the remarks section of the filed flight plan described the flight as a “training flight” and the left-seat pilot’s plan to obtain a type rating for the accident airplane model, it is likely the pilot in the left seat was the flying pilot for the majority of the flight. Although the right-seat pilot's autopsy noted coronary artery disease, the condition was poorly described. The circumstances of the accident are not consistent with sudden physical impairment or incapacitation; therefore, it is unlikely it contributed to the event. Toxicology testing identified diphenhydramine, which can cause significant sedation, in the right-seat pilot’s blood. However, the level present at the time of the accident was too low to quantify. Therefore, it is unlikely effects from diphenhydramine contributed to the accident. Prior to entering the descending right turn, air traffic control noted that the airplane was not following assigned headings and altitudes and the pilots’ reported having autopilot problems. Subsequently, the pilots’ reported they were using the right attitude indicator as they had difficulties with the left-side indicator. Information was insufficient to evaluate whether the reported difficulties were the result of a malfunction of the autopilot or the pilots’ management of the autopilot system. However, the reported difficulties likely increased the pilots’ workload, may have diverted their attention while operating in IMC and icing conditions, resulting in task saturation, and may have increased their susceptibility to spatial disorientation. It is also possible that the onset of spatial disorientation was the beginning of the pilots’ difficulties maintaining the airplane’s flight track and what they perceived to be an instrumentation problem. Regardless, since the left seat pilot was not rated to fly the airplane, the right seat pilot’s workload would have increased by having to diagnose the issue, assess the situation, and maintain positive airplane control. The airplane’s track data are consistent with the known effects of spatial disorientation, leading to an inflight loss of control and subsequent inflight breakup.

According to the pilot, during the landing roll, the airplane "began to drift sharply to the left." The pilot reported that, although there were no wind gusts reported, he felt as though a wind gust was pushing the airplane to the left. He attempted to maintain directional control with rudder pedal application, and he applied full right aileron. The airplane continued to drift to the left, and the pilot attempted to abort the landing by applying full throttle and 25° of flaps. He reported that the airplane continued to drift to the left and that he was not able to achieve sufficient airspeed to rotate. The airplane exited the runway, the pilot pulled the throttle to idle, and he applied the brakes to avoid obstacles. However, the airplane impacted the runway and taxiway signage and came to rest in a drainage culvert. The airplane sustained substantial damage to both wings. The published METAR for the accident airport reported that the wind was from 290° at 15 knots, and wind gusts exceeded 22 knots 1 hour before and 1 hour after the accident. The pilot landed the airplane on runway 20. The maximum demonstrated crosswind component for the airplane was 17 knots. The pilot reported that there were no preaccident mechanical malfunctions or failures with the airplane that would have precluded normal operation.

The instrument-rated private pilot was conducting a personal cross-country flight in the multiengine airplane under instrument flight rules (IFR). As the flight neared its destination, the controller issued clearance for a GPS approach, and, shortly thereafter, the pilot informed the controller that he needed to review the approach procedure before continuing the approach. The controller acknowledged, and, after the pilot reported that he was ready to proceed with the approach, the controller again issued clearance for the GPS approach. Radar data showed that, during the approach, the airplane tracked a course that was offset about 0.5 miles right of the final approach course until it was about 1 mile from the runway threshold. The airplane then turned left towards the threshold and descended to an altitude of about 145 ft above ground level over the runway threshold before the pilot performed a missed approach. It is likely that the pilot performed the missed approach because he was unable to align the airplane with the runway before it crossed the threshold. The controller provided radar vectors for the airplane to return to the approach course and cleared the airplane a third time for the GPS approach to the runway. Radar data showed that the airplane was established on the final approach course as it passed the initial approach fix; however, before it reached the final approach fix, its airspeed slowed to about 111 knots, and it began a left turn with a 25 degree bank angle. About 18 seconds later, while still in the turn, the airplane slowed to 108 knots and began descending rapidly. The airplane's rate of descent exceeded 10,000 feet per minute, and it impacted the ground about 9 miles from the destination airport. Examination of the accident site showed that the airplane was severely fragmented and fire damaged with debris scattered for about 450 feet. Postaccident examination of the wreckage did not reveal evidence of any preimpact failures; however, damage to the left engine indicated that it was not producing power at the time of the accident. The severity of impact and fire damage to the airplane and engine precluded determination of the reason for the loss of left engine power. Weather conditions present at the time of the accident were conducive to super cooled liquid water droplets, and the airplane likely encountered moderate or greater icing conditions. Several pilot reports (PIREPs) for moderate, light, trace, and negative icing were reported to air traffic control but were not distributed publicly into the national airspace system, and there was no airmen's meteorological information (AIRMET) issued for icing. However, the pilot received standard and abbreviated weather briefings for the flight, and his most recent weather briefing included three PIREPs for icing conditions in the area of the accident site. Given the weather information provided, the pilot should have known icing conditions were possible. Even so, the public distribution of additional PIREPs would have likely increased the weather situational awareness by the pilot, weather forecasters, and air traffic controllers. The airplane was equipped with deicing and anti-icing systems that included wing and empennage deice boots and engine inlet heaters. Due to impact damage to the cockpit, the positions of the switches for the ice protection systems at the time of the accident could not be determined. Although the airplane's airspeed of 108 knots when the steep descent began was above its published stall speed of 77 knots, both bank angle and ice accretion would have increased the stall speed. In addition, the published minimum control airspeed was 93 knots. It is likely that, after the airplane passed the initial approach fix, the left engine lost power, the airplane's airspeed began to decay, and the asymmetric thrust resulted in a left turn. As the airspeed continued to decay, it decreased below either stall speed or minimum control airspeed, and the airplane entered an uncontrolled descent.