What happened
Before departing from St. Louis International Airport, the pilot inquired with the operations manager at M. Graham Clark Airport regarding the local weather. The manager reported unfavorable conditions, noting an overcast ceiling of 300 feet and visibility of only 3/4 miles due to rain and mist. Despite this, the Cessna Citation 525KL departed St. Louis at 14:11 CST.
During the flight, the pilot communicated with Springfield Approach Control, receiving instructions for an ILS approach to runway 2 at Springfield-Branson Regional Airport. The pilot subsequently requested a diversion to Point Lookout to perform a GPS approach for runway 11. Air traffic control cleared the aircraft to descend to 3,000 feet MSL. Radar tracking confirmed the aircraft crossing the initial waypoint and turning toward the approach heading, with the aircraft descending to 2,500 feet MSL.
After being cleared to transition to an advisory frequency, the pilot acknowledged the instructions. The operations manager at the destination airport reported hearing the pilot announce the inbound GPS approach on the common frequency. Shortly after, radar showed the aircraft descending below 2,500 feet MSL. The final radar contact occurred at 15:09:48 CST, positioning the aircraft five nautical miles from the airport at 2,100 feet MSL. Following unsuccessful attempts by Springfield Approach to re-establish contact, a search operation was initiated.
Findings
An inspection of the wreckage showed no mechanical irregularities. However, toxicology results from the pilot indicated the presence of Doxepin in the kidney and liver. This medication, prescribed for a medical condition, is known to potentially cause drowsiness. Additionally, reports indicated the pilot had experienced significant sleep deprivation in the days leading up to the flight.