COLUMBIA AIRCRAFT MFG LC41 550FG — Erwin, TN

What happened

The instrument-rated private pilot was on an instrument flight rules (IFR) cross-country flight; while en route, the pilot elected to divert to an intermediate airport to "check the weather." The pilot was subsequently provided a weather briefing that described a line of convective weather along the intended route of flight. The airplane departed about 45 minutes later and flew east along the south side of an east-west line of thunderstorms. The pilot was communicating with air traffic control, and when asked by the air traffic controller if he had onboard weather information, the pilot stated that he had NEXRAD. The airplane was equipped with satellite-delivered weather information service that was displayed in the cockpit, and it is likely that the pilot was referring to NEXRAD images provided by that system.  The pilot requested and was granted permission to turn north in order to navigate through the line of storms toward his destination. Ground track and weather radar data revealed that the airplane penetrated a thunderstorm cell of strong intensity The pilot subsequently lost control of the airplane before it rapidly descended to ground impact.

The wreckage debris path was compact, and examination of the wreckage revealed extensive fragmentation and thermal damage. No preimpact mechanical malfunctions were noted that would have precluded normal operation of the airplane. The impact damage to the engine and propeller were consistent with the engine operating at a high power setting at the time of impact.

The satellite-delivered weather information likely being used by the pilot did not provide real-time weather radar images in the cockpit, with a delay between the time the weather was observed and when it was provided. It is likely that the pilot attempted to maneuver through the line of thunderstorms, but the time delay in the satellite-delivered weather data likely resulted in inadvertent penetration of a severe thunderstorm cell.

The investigation could not determine the color intensity of the precipitation being displayed to the pilot on cockpit avionics around the time of the accident. However, the most extreme color band that could have been shown would have been dark orange, which was classified as 55 dBZ. On the WSR-88D and satellite-delivered radar images, orange was classified as 40 dBZ. The WSR-88D Level 2 reflectivity product revealed that the weather reflectivity, around the accident location, ranged from 5 dBZ to 55 dBZ.

Postaccident toxicology testing revealed the presence of citalopram, an antidepressant medication, and ethanol. Citalopram is one of four medications that has been approved by the FAA for the treatment of depression. Personal medical records documented that the pilot's depression was well controlled with citalopram, and the pilot had no adverse effects from the medication. Therefore, there is no evidence that depression or the citalopram impaired the pilot's decision-making ability or his ability to safely operate the airplane. The ethanol detected was likely from postmortem production. Further, considering that the level of the ethanol was below a level that would be considered impairing, the ethanol detected did not impair the pilot nor contribute to the accident.

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