In May 2021, seven people died when a Citation 501, N66BK, crashed into Percy Priest Lake near Nashville, Tennessee, shortly after taking off.
It was a little before 11 a.m. There was an overcast at 1,300 agl (1,850 msl), but no precipitation and good visibility below the clouds. The pilot had topped off the plane for the two-hour flight from Smyrna Airport (KMQY) to Palm Beach International Airport (KPBI) in Florida. After taxiing to Runway 32, he was instructed to turn to a heading of 090 after takeoff and maintain 3,000. His IFR clearance, which he had received previously, said to expect a climb to FL 330 10 minutes after departure.
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“OK,” the pilot replied, “we’re going 090 at or above 3,000.” The tower corrected him, and the pilot acknowledged. The tower controller then instructed him to contact Nashville departure, and he replied, “Going to Nashville.”
ADS-B showed the Citation climbing at 2,000 fpm and beginning a right turn as it entered the overcast. About two minutes after takeoff, it was at 2,900 msl with a heading of 090 and a ground speed of 200 knots, but the pilot had yet to check in with Nashville.
Departure gave him a nudge: “N66BK, are you on frequency?”
The pilot acknowledged.
“N66BK, say altitude, you are radar contact three north of Smyrna, fly heading of 130.”
“Say altitude,” in these circumstances, often means, “You are not at your assigned altitude.” The Citation had by now descended to 2,500 feet.
Silence. The Citation continued turning right, reaching 160 degrees. After 15 seconds the departure controller repeated, “N66BK, did you copy your heading 130?” The controller said nothing about altitude, although at this point the Citation was below 2,000 feet.
The pilot replied, “130 66BK.” He was not heard from again.
After reaching 2,900 feet, the Citation had begun to descend, its airspeed rising to 290 knots. At 1,875 feet, banked 60 degrees to the right, it again climbed, this time at 6,000 fpm. It reached 2,975 feet in 14 seconds before rolling left and entering a final dive. It was in a 120-degree left bank when it hit the water at 350 knots. An eyewitness said, “like a lawn dart.”
The National Transportation Safety Board (NTSB) saw in the Citation’s erratic flight path an obvious case of spatial disorientation, and since the loss of control occurred during initial climb, attributed it to the somatogravic illusion.
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That illusion arises from the fact that, without help from visual cues, the balance mechanism in our inner ears cannot distinguish forward acceleration from pitching up, or deceleration from pitching down. Immediately after takeoff, when the airplane is both nose up and accelerating, the normal uphill sensation of climbing is magnified, especially in powerful airplanes that gain speed rapidly. The pilot senses—incorrectly—that the nose is rising and pitches down accordingly, perhaps without even being consciously aware of doing so. The airplane stops climbing, begins to descend, and may fly under control into the terrain.
Every instrument pilot, or pilot who takes off VFR at night in the desert or over water, is potentially subject to this illusion. Why is it that a few crash and most don’t? Since reliance on instruments is the obvious (and only) defense, we can reframe the question: Can a pilot who knows how to fly by instruments lack the self-discipline to rely steadfastly on them and ignore physical sensations, no matter how persuasive?
The Citation pilot, 59, had a commercial ticket with ratings for single and multiengine land, instrument, and helicopter, and a CE-500 type rating that had not been renewed at the time of the accident. His wife was the founder of a church that preached weight loss through faith, an inspired theology thanks to which the couple was blessed with an MU-2B as well as the Citation. The pilot had started with a 172 and a Baron, and, according to a friend, moved quickly from one type to another. He had logged 1,680 hours, 83 of them in the Citation. His total actual instrument experience was only 40 hours, six of them in the Citation.
He had taken the FlightSafety type rating course 16 months before the accident, but “did not meet the requisite performance level” to attempt the check ride. After returning home from FlightSafety, he engaged an instructor, with whom he flew 11.4 hours. That instructor told the NTSB that he “saw no issues” with the pilot’s ability to operate the Citation in IMC. The designated examiner who gave him his type rating check ride also said that he was “very competent” and had “full confidence” in his ability.
After receiving his type rating, the pilot flew about 25 hours with another instructor, who described these flights not as instructing but as something they enjoyed doing together and that helped the pilot get more comfortable in the Citation.
That instructor, who had 10,000 hours in jets and 3,000 in Citations, provided a more nuanced assessment. The pilot was safe, and excellent with checklists, but “always behind the airplane” and unable to visualize his situation in time and space without consulting his iPad.
He “struggled” with the Citation’s autopilot, which he found harder to use than the one in his MU-2, and he preferred to hand-fly the airplane. He had expressed a desire to fly to New York, Los Angeles, and Atlanta, but the instructor discouraged him, feeling that he was not ready to operate in complex ATC environments.
The Citation was over gross, and its CG may have been unusually far forward, but neither of those conditions would account for a loss of control. Perhaps the trouble the pilot had with situational awareness and mastering the autopilot was more relevant: He was just a little out of his depth.
Nevertheless, the instructor was baffled that the pilot could have become disoriented on the departure, which he had flown many times. He speculated that he might have mistakenly flipped the avionics master switch when he intended to turn off the ignitors, as he had done twice before.
If the pilot’s disorientation began with the somatogravic illusion, it evidently progressed to a more general kind of vertigo. The Citation’s surging, plunging flight path was suggestive of a general breakdown, a sort of panic in which the attitude indicator becomes incomprehensible and the pilot relies entirely on physical sensations. It was much more like the flight path of a VFR pilot who has strayed into a thunderstorm than that of a jet pilot in light IMC.
The principal lesson to be learned from the accident is that this can happen. The weather was benign. The trip was simple. The pilot, although no ace, had been judged capable and safe. He had ample experience in fast, heavy, complex airplanes. He was type rated in the jet. And yet…
This column first appeared in the April Issue 957 of the FLYING print edition.
