COLUMBIA AIRCRAFT MFG LC41 550FG — Gurdon, AR

What happened

The private pilot and pilot-rated passenger were conducting a cross-country flight in the airplane. The pilot's communications with air traffic control (ATC) were unremarkable until the pilot requested an instrument flight rules (IFR) clearance to climb to 25,000 ft mean sea level (msl) to do an "equipment test"; at that time, the airplane was at a cruise level of 17,500 ft msl. The controller granted the pilot's request, and radar showed that the airplane climbed to 25,000 ft, where it remained for about 3 minutes and 25 seconds. The pilot then requested to descend to 17,500 ft, and the airplane started to descend before the controller could issue a clearance. The controller then cleared the pilot to descend to 19,000 ft and asked the pilot if everything was alright. The pilot responded that the airplane was experiencing an "equipment issue" and requested to cancel the IFR clearance. The controller cleared the pilot to descend and maintain 17,000 ft and asked if he needed assistance. The pilot responded that he was "okay for now." About 1 minute later, the pilot declared an emergency. the controller requested the pilot to state the nature of the emergency, but the pilot's response was unintelligible. The controller attempted to contact the airplane without success. Radar data showed that the airplane descended more than 17,000 ft in 2 minutes 12 seconds, and radar contact with the airplane was lost when the airplane descended to an altitude of about 3,100 feet.

The airplane impacted terrain in an almost-vertical nose-down orientation, and a postimpact fire ensued. The recovered airframe pieces were examined, but, due to the severe airframe fragmentation, flight control continuity could only be established from the rudder surface to overload separations on the control cables leading to the cockpit. One of the two speedbrake modules was found deployed. The airplane's fuel, environmental , anti-icing, and oxygen systems and cockpit gauges and instruments could not be examined due to severe impact and fire damage. Examinations of the engine, propeller, and turbochargers revealed no anomalies that would have precluded normal operation, and propeller signatures were consistent with low power at the time of impact.

According to weather information, the airplane was most likely not in clouds during the descent from 25,000 to about 6,000 ft, so airplane icing was not likely. The airplane would likely have been in clouds below 6,000 ft, but the airplane likely remained in visual meteorological conditions during that part of the descent and entered instrument meteorological condition immediately before impacting the terrain. The pilot radioed that the airplane was having "an equipment issue," but, due to the severe impact and postcrash fire damage to the airplane's systems, neither the specific equipment issue nor the reason why the airplane descended rapidly could be determined.

The pilot had evidence of use of amphetamine. However, because the blood results are from heart blood and amphetamine undergoes significant post mortem redistribution which may increase central levels (such as heart levels) by 3-8 times, the blood level cannot be used to determine whether the pilot was using the drug medicinally or abusing it. Similarly, the urine drug level of 7 could have been the result of either medicinal use or abuse. While it is likely that the pilot had some psychoactive effects from his use of amphetamine at the time of the accident, whether or not it was impairing could not be determined from this investigation. The pilot rated passenger's toxicology testing demonstrated evidence of previous use of marijuana. However, no active/parent THC was identified in brain. Since THC is stored in brain and can remain there for long periods, this indicates the pilot rated passenger's use of THC was likely several days before. It is therefore unlikely that the pilot rated passenger was impaired by his use of marijuana during the flight. Overall, it is unlikely the pilot rated passenger was impaired by his use of marijuana at some point prior to the accident. The investigation was unable to determine if the pilot's use of amphetamine was medicinal or misuse and was unable to determine from the available information whether its likely psychoactive effects, present during the flight, were impairing.

An editorial "what led to it / how to avoid it" analysis for this accident is generated separately and will appear here.