In May 2021, a tragic accident occurred when a Citation 501, N66BK, crashed into Percy Priest Lake near Nashville, Tennessee, claiming the lives of seven individuals shortly after takeoff.
The incident happened just before 11 a.m. The skies were overcast at 1,300 feet above ground level, while visibility remained clear below the clouds. The pilot had completed fueling for the two-hour flight, which was set to take off from Smyrna Airport (KMQY) and head to Palm Beach International Airport (KPBI) in Florida. After taxiing to Runway 32, he received instructions to turn to a heading of 090 after takeoff and to maintain an altitude of 3,000 feet. His IFR clearance, provided earlier, anticipated a climb to FL 330 ten minutes after departure.
“Understood,” the pilot responded, “we’re heading 090 at or above 3,000.” After a correction from the tower, the pilot acknowledged this instruction. The tower controller then directed him to contact Nashville departure, to which he replied, “Going to Nashville.”
ADS-B data showed the Citation climbing at a rate of 2,000 feet per minute and beginning a right turn as it entered the cloud cover. About two minutes into the flight, the aircraft was at 2,900 feet mean sea level, maintaining a 090 heading with a ground speed of 200 knots, but the pilot had not yet checked in with Nashville.
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Departure control prompted, “N66BK, are you on frequency?”
The pilot confirmed his position.
“N66BK, report altitude; you are radar contact three miles north of Smyrna, adjust to a heading of 130.”
The request for altitude typically indicates that the aircraft is not at the expected level. By this time, the Citation had descended to 2,500 feet.
There was silence as the Citation continued its right turn, heading 160 degrees. After a lengthy pause, the controller reiterated, “N66BK, did you copy your heading 130?” The aircraft was now below 2,000 feet without any mention of altitude from the controller.
The pilot finally replied, “130 66BK.” Remarkably, that was the last transmission they received from him.
Following a peak at 2,900 feet, the Citation began a descent, its airspeed increasing to 290 knots. At 1,875 feet, while banked at 60 degrees to the right, it briefly climbed at a rate of 6,000 fpm. In a matter of seconds, it reached 2,975 feet before rolling left and plunging downward. Witnesses described the impact as “like a lawn dart” as the aircraft hit the water at 350 knots.
The National Transportation Safety Board (NTSB) identified the Citation’s erratic flight pattern as a clear example of spatial disorientation, attributing the loss of control during initial climb to a somatogravic illusion.
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This illusion emerges because, without visual references, our inner ear’s balance system struggles to discern forward acceleration from a climb or deceleration from a descent. Immediately after takeoff, as the airplane pitches up and accelerates, pilots may feel an exaggerated sensation of climbing, prompting them to mistakenly pitch down. This misperception can lead the aircraft to descend uncontrollably into the terrain.
All instrument pilots, particularly those departing VFR at night or over featureless terrain, are susceptible to this illusion. The crucial question remains: Can a pilot trained in instrument flying still lack the self-discipline to trust their instruments over physical sensations, regardless of how dominant those sensations may feel?
The pilot of the Citation, who was 59 years old, held a commercial pilot license with ratings for single and multi-engine land planes, as well as helicopters, but his CE-500 type rating had not been renewed at the time of the accident. His wife was the founder of a church revolving around faith-based weight loss, a belief that led the couple to own both the Citation and an MU-2B. Having started in a 172 and progressed to a Baron, he had accumulated a total of 1,680 flight hours, but only 83 of those were in the Citation. His actual instrument experience was limited to 40 hours, with just six logged in the Citation.
Sixteen months prior to the accident, he attended a FlightSafety type rating course but did not meet the expected performance requirements to take the check ride. Afterward, he worked with an instructor for 11.4 hours, during which the instructor reported seeing no apparent issues with his ability to operate the Citation in IMC conditions. The examiner who conducted his type rating check ride also deemed him to be “very competent” with “full confidence” in his flight skills.
Post-type rating, the pilot logged approximately 25 additional hours flying with another instructor who described their time not as traditional instruction but as enjoyable flights that helped the pilot acclimate to the Citation.
The instructor, with 10,000 hours in jets and 3,000 in Citations, provided a more detailed evaluation. He noted that while the pilot excelled with checklists and demonstrated overall safety, he often fell behind the aircraft and struggled to visualize his circumstances in space and time without the assistance of his iPad.
He found the Citation’s autopilot challenging to use compared to that of his MU-2 and preferred manual flying. Although he had ambitions to fly to New York, Los Angeles, and Atlanta, his instructor advised against it, believing he was not yet prepared for complex air traffic control situations.
While the Citation was overloaded and possibly had a forward center of gravity, these factors alone would not account for the loss of control. The pilot’s challenges with situational awareness and autopilot operation were likely more relevant; he was evidently out of his depth.
Ultimately, the instructor was left perplexed as to how the pilot could have become disoriented during the departure phase, which he had flown many times. He speculated that the pilot might have inadvertently flipped the avionics master switch while attempting to deactivate the ignitors, an action he had repeated previously.
If the pilot’s disorientation began with the somatogravic illusion, it appeared to advance toward a more generalized type of vertigo. The erratic flight path of the Citation suggested a complete breakdown of control, resembling the panic experienced by a VFR pilot who unexpectedly finds themselves in turbulent conditions rather than a seasoned instrument-rated pilot in basic IMC.
The primary takeaway from this accident is the reminder that such events are possible. The weather was non-threatening, the route straightforward, and although the pilot was not a top-tier aviator, he was considered capable and safe. He possessed sufficient experience in complex aircraft and had completed the type rating for the jet. And yet… the unthinkable occurred.
This column first appeared in the April Issue 957 of the FLYING print edition.
Based on an article from flyingmag.com: https://www.flyingmag.com/somatogravic-all-was-well-for-a-pilot-and-then-it-suddenly-wasnt/
