What Happened
On December 7, 2023, at 11:03 a.m. central standard time, Beech 35-C33 N5891J crashed near Pulaski, Tennessee. The private pilot and passenger were killed, and the airplane was destroyed. What began as a cross-country flight with normal radio calls developed into increasing altitude and airspeed changes, lost communications, and a rapid uncontrolled descent.
The airplane departed Knoxville Downtown Island Airport about 9:48 a.m. for Saline County Regional Airport in Benton, Arkansas, approximately 430 nautical miles away. It initially flew a generally westbound track, leveled near 2,500 feet mean sea level, and later climbed to 6,500 feet.
For part of the early flight, headings and pilot-controller communications were unremarkable. Near the climb to cruise, however, the airplane’s groundspeed dropped before increasing again after level-off. It then maintained approximately 6,500 feet and a groundspeed just below 130 knots for about 10 minutes.
After about 10:20 a.m., the flight profile changed. The airplane descended toward 6,000 feet as speed increased, then climbed back toward 6,500 feet while slowing. The cycle repeated. Over roughly 25 minutes, the oscillations became more pronounced, with altitude deviations reaching about 1,500 feet.
A controller told the pilot that the airplane was left of course. She acknowledged the call, but the deviations continued to worsen. She eventually stopped responding to routine radio calls. Faint emergency transmissions from the pilot and passenger were received later as the airplane descended.
During the final portion, the descent rate exceeded 10,000 feet per minute and groundspeed reached about 228 knots. The airplane struck terrain before control was restored.
Investigation Findings
The NTSB examined both the recorded flight path and the pilot’s training history. Instructors who had flown with her described recurring difficulty with manual aircraft handling and cockpit automation, including autopilot and trim use. One instructor had explicitly considered the high-performance airplane beyond her proficiency level.
The aircraft had been purchased about a year and a half before the accident. Ownership time did not establish proficiency in the systems. The training accounts described difficulties maintaining situational awareness and understanding how the autopilot’s pitch commands interacted with the requirement for manual pitch trim.
Investigators considered the stable early heading consistent with likely autopilot use. They then examined a possible explanation for the repeating climbs and descents: an improperly trimmed airplane and pilot control inputs working against autopilot pitch commands.
That explanation was a possibility, not a fully demonstrated sequence of switch positions. Inputs that arrived late or opposed the automatic pitch commands could magnify the oscillations instead of damping them. The recorded vertical profile was consistent with such pilot-induced oscillations, and the Board’s probable cause identified the failure to maintain control and the resulting oscillations.
Wreckage examination did not reveal an anomaly that would have prevented normal operation. But fragmentation and fire damage prevented complete evaluation of the flight controls and autopilot. The evidence therefore did not justify claiming that every component had been conclusively tested and ruled out.
Toxicology identified medications that could have impairing effects. Available samples were limited to tissues, and the investigation lacked enough medical and circumstantial evidence to establish a contribution. The NTSB noted that medication or an underlying condition might have affected performance but could not determine that it did, particularly given the pilot’s documented baseline proficiency difficulties.
The distinction between findings and hypotheses matters in this case. The worsening flight path and loss of control were established. A trim and autopilot interaction was a possible mechanism consistent with that path. Medication contribution and a complete assessment of the damaged systems remained unresolved.
NTSB Probable Cause
The pilot’s failure to maintain airplane control, which resulted in pilot-induced oscillations and a subsequent loss of control and impact with terrain.
Safety Lessons
The following takeaways apply the investigation findings to flight planning and cockpit decisions.
- Train the installed autopilot and trim system together. Know how the actual installation commands pitch, signals trim requirements, and is disconnected under its approved procedures. Treat automation training as aircraft-control training rather than just learning how to select a heading.
- Recognize a worsening oscillation as a control problem. Repeated climbing and descending with increasing amplitude calls for immediate attention to aircraft control and the applicable abnormal procedures. Trying to correct every excursion without understanding the system interaction can add to the workload.
- Use instructor feedback to define operating limits. Recurring problems with manual handling or systems deserve a structured proficiency plan before passenger travel. Familiarity with a route or time owning an airplane does not resolve an identified handling deficiency.
Watch the Full Analysis
Frequently Asked Questions
Q: What caused the Beech 35-C33 crash near Pulaski?
A: The NTSB found that the pilot failed to maintain control, resulting in pilot-induced oscillations, loss of control, and terrain impact.
Q: Did the autopilot definitely malfunction?
A: No definite malfunction was established. The NTSB considered a possible interaction among autopilot pitch inputs, manual trim, and pilot control inputs. Damage prevented complete evaluation of the systems.
Q: Did medication cause this accident?
A: The investigation identified potentially impairing medications but could not establish whether their effects or an underlying condition contributed to the accident.
Sources and References
