N9436XCessna 210A · 1961

On September 8, 2019, at 0630 eastern daylight time, a Cessna 210A, N9436X, was destroyed when it impacted the Gulf of. The commercial pilot and passenger were fatally injured. The personal flight was conducted under the provisions of Title 14 Code of Federal Regulations Part 91.

The pilot had filed an instrument flight rules (IFR) flight plan for the accident flight, with a planned destination of Savannah/Hilton Head International Airport (SAV), Savannah, Georgia. On the morning of the accident flight, the pilot was departing from The Florida Keys Marathon International Airport (MTH), Marathon, Florida but had not contacted air traffic control to receive an IFR clearance. Review of ADS-B track data for the accident flight revealed that it departed on runway 25 at 0629 and initially made a right climbing turn. The airplane reached an indicated altitude of 425 ft mean sea level about 90° through the turn, before descending in the turn and impacting the water. The airplane’s groundspeed continued to increase, from about 70 knots at liftoff, to 100 knots at the height of the right climbing turn, to 146 knots at the end of the data. Review of airport surveillance video depicted the airplane’s takeoff, initial climb, and turn toward an area of dark open water underneath a scattered cloud layer.

The pilot held a commercial pilot certificate with ratings for airplane single-engine land and instrument airplane. His most recent Federal Aviation Administration (FAA) third-class medical certificate was issued on February 10, 2018. At that time, he reported a total flight experience of 1,500 hours. The pilot’s logbook was not recovered. The pilot’s total and recent instrument experience could not be determined.

The recorded weather at MTH, at 0653, included: visibility 10 miles and scattered clouds at 2,800 ft.

Review of data from the U.S. Naval Observatory revealed that civil twilight began at 0645 and sunrise was at 0708.

The wreckage was examined following its recovery from the water to a storage facility. Both wings and the engine separated during impact. The right wing exhibited more impact damage than the left wing. The right flap separated, and its actuator was found in the retracted position. The left flap remained attached, exhibited impact damage, and was partially extended. The right aileron separated and only small pieces of it were recovered. The left aileron remained partially attached to a separated section of left wing. Both wingtip sections separated and were not recovered. The right horizontal stabilizer and right elevator exhibited leading edge damage and separation at the outboard section. The left horizontal stabilizer and left elevator were less damaged. There was no damage to the vertical stabilizer or rudder.

The landing gear was retracted. Control continuity was confirmed from all control surfaces (except for the right aileron) through cable breaks at the fuselage, to the cockpit controls. The cable breaks exhibited broomstraw features consistent with overload separation. Pieces of the right aileron were recovered but the right aileron bellcrank was not recovered. The right aileron cable was recovered and exhibited broomstraw features consistent with overload separation. Measurement of the elevator trim jackscrew corresponded to an approximate neutral elevator trim position.

The cockpit was crushed and separated from the fuselage. The pilot and copilot seats were not recovered. The fuel selector valve was positioned to the left fuel tank. The attitude indicator gyro was disassembled for examination. Its rotor and housing were corroded. The directional gyro was also disassembled for examination. It’s rotor and housing were corroded; however, one rotational score was observed on the housing. The vacuum pump was disassembled, its rotor, vanes, and shear shaft remained intact. Fuel was recovered from the fuel selector valve and the fuel manifold. It was consistent in color and odor to 100 low lead aviation gasoline.

The propeller separated from the crankshaft flange. One propeller blade was twisted while the other blade was bent aft and exhibited a leading edge gouge. The spark plugs were removed and their electrodes were intact and gray in color. The crankshaft was rotated by hand via the propeller flange. Camshaft, crankshaft, and valve train continuity were confirmed to the rear accessory section of the engine. Thumb compression was attained on all cylinders. Borescope examination of the cylinders did not reveal any anomalies. Both magnetos produced spark at all posts when rotated via an electric drill. The engine driven fuel pump remained attached and could be rotated by hand. It was then disassembled and no anomalies were noted. The oil filter was opened and its element was absent of contamination. The fuel metering unit remained partially attached to the engine and did not exhibit any anomalies.

Spatial Disorientation

The FAA's Pilot's Handbook of Aeronautical Knowledge contained guidance which stated that "under normal flight conditions, when there is a visual reference to the horizon and ground, the sensory system in the inner ear helps to identify the pitch, roll, and yaw movements of the airplane. When visual contact with the horizon is lost, the vestibular system becomes unreliable. Without visual references outside the airplane, there are many situations where combinations of normal motions and forces can create convincing illusions that are difficult to overcome."

The Handbook also advised, "unless a pilot has many hours of training in instrument flight, flight in reduced visibility or at night when the horizon is not visible should be avoided."

The FAA Airplane Flying Handbook (FAA-H-8083-3) described some hazards associated with flying when visual references, such as the ground or horizon, are obscured. "The vestibular sense (motion sensing by the inner ear) in particular tends to confuse the pilot. Because of inertia, the sensory areas of the inner ear cannot detect slight changes in the attitude of the airplane, nor can they accurately sense attitude changes that occur at a uniform rate over a period of time. On the other hand, false sensations are often generated; leading the pilot to believe the attitude of the airplane has changed when in fact, it has not. These false sensations result in the pilot experiencing spatial disorientation."

FAA Publication "Spatial Disorientation Visual Illusions" (OK-11-1550), states in part "false visual reference illusions may cause you to orient your aircraft in relation to a false horizon; these illusions are caused by flying over a banked cloud, night flying over featureless terrain with ground lights that are indistinguishable from a dark sky with stars, or night flying over a featureless terrain with a clearly defined pattern of ground lights and a dark starless sky." The publication further provides guidance on the prevention of spatial disorientation. One of the preventive measures was "When flying at night or in reduced visibility, use and rely on your flight instruments." It further states "if you experience a visual illusion during flight (most pilots do at one time or another), have confidence in your instruments and ignore all conflicting signals your body gives you. Accidents usually happen as a result of a pilot's indecision to rely on the instruments."

The FAA publication Medical Facts for Pilots (AM-400-03/1), described several vestibular illusions associated with the operation of aircraft in low visibility conditions. Somatogravic illusions, those involving the semicircular canals of the vestibular system, were generally placed into one of four categories, one of which was the "graveyard spiral." According to the text, the graveyard spiral, "…is associated with a return to level flight following an intentional or unintentional prolonged bank turn. For example, a pilot who enters a banking turn to the left will initially have a sensation of a turn in the same direction. If the left turn continues (~20 seconds or more), the pilot will experience the sensation that the airplane is no longer turning to the left. At this point, if the pilot attempts to level the wings this action will produce a sensation that the airplane is turning and banking in the opposite direction (to the right). If the pilot believes the illusion of a right turn (which can be very compelling), he/she will reenter the original left turn in an attempt to counteract the sensation of a right turn. Unfortunately, while this is happening, the airplane is still turning to the left and losing altitude.

The Florida Medical Examiner’s Office District 16, Marathon, Florida, performed an autopsy on the pilot’s remains. The cause of death for the pilot was multiple blunt force injuries.

Toxicology testing performed at the Federal Aviation Administration (FAA) Forensic Sciences Laboratory found 0.059 (gm/hg) ethanol in the pilot’s muscle; however, no ethanol was detected in the pilot’s brain tissue, which was consistent with postmortem production.

The plot’s FAA medical certification file dated back to 1978. The pilot was granted a SODA on May 6, 1985 for an uncorrected distant vision of 20/200 bilaterally that was corrected to 20/20. At his February 6, 2003 examination he reported having had bilateral cataract surgery the previous year; his bilateral uncorrected distant vision was 20/20. Over time, his uncorrected vision changed; at his second most recent examination on September 2, 2016, both eyes had an uncorrected vision of 20/50, but could be corrected to 20/20.

At the pilot’s most recent physical examination on February 10, 2018, the aviation medical examiner determined that the pilot had an abnormal field of vision and that the corrected vision in his right eye was 20/100. He was deferred to the FAA to provide reports from his ophthalmologist. Based on information provided from his ophthalmologist, the FAA granted a special issuance for the pilot’s glaucoma that needed annual renewal. His ophthalmologist reported in a February 2019 letter to FAA dated that the pilot had chronic macular edema in his right eye because of a retinal vein obstruction and that he had normal tension glaucoma in both eyes. The FAA granted a special issuance for the glaucoma that would expire on February 28, 2020. The pilot was also required to take a medical flight test; he was issued a statement of demonstrated ability (SODA) for his right visual field defects on September 25, 2018.