WPR16FA087

The pilot's loss of aircraft control during a low-altitude ash dispersal maneuver. Contributing to the accident was his degraded performance due to his medical conditions.

The flight was intended for the dispersal of the passenger's deceased husband's ashes, which took place over a river. The dispersal procedure called for the ashes to be placed in a bag that was cinched at the top and tethered to the airframe inside the cabin. The pilot was required to slow the airplane and fly it in a banking maneuver, and the passenger in the aft cockpit would then throw the bag out through the opened aft canopy and retrieve the bag once the ashes had been released into the slipstream. Witnesses described the airplane flying low and slow over the river channel and then rolling left and nose-diving into the water. Examination of the wreckage revealed that the rear sliding canopy was most likely open at the time of impact. The ash dispersal bag was not located. Therefore, based on the accident location, the observed maneuver, and the open rear canopy, the accident likely occurred at some point during the ash dispersal sequence. Postaccident examination did not reveal any anomalies with the airframe or engine that would have precluded normal operation. Several maintenance discrepancies were found; however, none would have resulted in the flight maneuver observed. Although the airplane was required to have undergone an inspection on an annual basis, the last inspection had occurred 22 months before the accident. Additionally, the pilot's last flight review had occurred 29 months before the accident, rather than the 24 months required. The airplane was equipped with dual controls and a swiveling rear seat; the seat was found in the forward and locked position, and the rear control stick appeared to have been removed and stowed. Therefore, passenger interference with the flight controls was unlikely. The pilot's autopsy revealed significant coronary artery disease, which review of his medical records indicated was apparently undiagnosed. Therefore, he was susceptible to an acute cardiac event or stroke (although the degree of blunt force injury prevented the evaluation of his brain.) Toxicology testing on the pilot identified sertraline, its metabolite desmethylsertraline, and trazodone in urine and cavity blood. According to his medical records, the pilot had insufficiently treated sleep disorders and had been taking trazodone as a sleep aid. Trazodone can increase the potential for arrhythmias in patients with pre-existing cardiac disease. In addition, the pilot had longstanding depression, and he had sufficient neurocognitive symptoms the preceding year from a series of concussions that he had stopped flying, driving, and working for several months. While the pilot's depression and symptoms related to his concussion were described as in remission, he had not undergone formal psychometric testing to evaluate these issues, and he had been self-medicating with sertraline, which he had been obtaining from another country out of concern about Federal Aviation Administration (FAA) regulations. He did not report the use of sertraline and trazodone to his FAA medical examiner. Chronically insufficient sleep can lead to chronic fatigue, which results in impaired attentiveness and slowed hazard detection and response times. The use of sleep aids such as trazodone in patients with inadequately treated sleep apnea may worsen the effects of sleep apnea and both directly and indirectly increase the degree of fatigue. The pilot's failure to have obtained the required condition inspection of the airplane or his required flight review may indicate some difficulty in attention and organization. Thus, the pilot had a number of medical conditions which could have contributed to him becoming inattentive, distracted, or debilitated during flight. He could have had a stroke or sudden cardiac event leading to a loss of control. Further, the negative cognitive effects from chronic fatigue resulting from his inadequately treated sleep disorders, chronic depression, and neurocognitive deficits from postconcussive syndrome would have increased the likelihood of the pilot failing to effectively manage airplane control while either setting up for, or during performance of the ash dispersal maneuvers.

Ash Dispersal Procedures Friends and fellow pilots gave similar descriptions of the ash dispersal procedures the pilot planned to use, stating that the bag had been used on multiple occasions by other pilots. One pilot stated that the bag was made of canvas, with a plastic inner liner that was cinched at the top, and tethered to the airframe from within the cabin. The procedures required slowing down the airplane, following which the passenger would throw the bag out of the window. The ashes would then release into the slipstream, and the bag would be pulled back in. The pilot's daughter flew with him in the airplane to disperse ashes over the water between downtown Seattle and Bainbridge Island in June 2015. She stated that on that occasion she was briefed by her father on the dispersal procedures both before and during the flight. Before takeoff, the ashes were placed in the bag, which she described as being about the size of a paper lunch bag. The bag was cinched closed with a rope, and tied by a longer rope to an interior airframe member on the right side. She sat in the rear seat, facing forward, and, when the time to disperse came, she slid the rear canopy open. The pilot then performed a shallow banking maneuver to the right, and she reached out with her hand holding the bag along the airframe side. She then let go of the bag, the rope unraveled, and the ashes immediately "puffed" and dispersed, and she pulled the bag back in. She reiterated that the airplane banked gently during the maneuver, and the bank never felt exaggerated. A friend of the passenger stated that he had initially been approached by her to drop the ashes, but he turned her down due to the design of his airplane not being conducive to performing the procedure. Another friend stated that he had been approached by her to drop the ashes and that they had agreed to do it on March 23. However, about 5 days before, he called asking that they reschedule because the weather looked bad. At that time, she stated that she had decided to cancel the drop altogether. Airframe Examination Following recovery, the airplane was examined by the NTSB investigator-in-charge and an airframe and powerplant mechanic who specialized in AT-6 aircraft maintenance. A complete examination report is included in the public docket for this investigation, and the following is a summary of pertinent findings. The forward fuselage sustained crush damage, compressing and fracturing most of the truss and shedding and separating the side skins. Aft of the cabin, the tailcone remained intact and sustained buckling damage to the forward skins. Aft of that damage, the horizontal and vertical stabilizers remained attached, and the left elevator had bent up about 90° midspan. The airplane was equipped with dual controls, and the rear control stick was detachable. Examination revealed that the rear control stick, which was found separated from the airframe, was undamaged. Its female socket fitting in the airframe control system did not reveal any indications of damage, and the upper tang of its storage dock on the cabin side had detached, consistent with the aft control stick being disconnected and stowed at the time of the accident. The rear seat was a swiveling "gunners seat" design and was found in the forward-facing position. Its adjustment pedal was forward and locked, and its locking pin was fully engaged with the forward position detent. The rear lap belt clasp was in the latched and closed position; the lap belt remained attached to the seat on both sides and had been cut by the Sheriff's Department divers during recovery of the passenger. The shoulder straps remained attached to the chair frame and were intact, with both belt clasps free, consistent with the shoulder straps not being used at the time of the accident. Neither the cremation bag, nor its attachment rope were located. The airplane was equipped with two sliding canopies and a fixed center canopy. The forward (pilot) canopy slid aft to allow for forward cockpit access, and the rear (passenger) canopy slid forward for rear cockpit access. A tubular-steel overturn pylon was mounted just behind the pilot's seat and about midspan of the center canopy. The sliding canopies and the forward cockpit had sustained extensive damage, such that the right sides of both canopy frames, the right sliding rails, and all the plexiglass had detached. Examination of the remaining components on the left side revealed that the rear sliding canopy remnants were in the full-forward (open) position, and the front left side of the rear canopy had wrapped around the overturn pylon. The forward sliding canopy remained attached to the left rail, had bent upwards, and was about 2 inches short of the full-forward (closed) position. The airplane was equipped with a hydraulically operated three-piece split flap. A wing flap was located below the trailing edge of each wing, and a center flap was located below the cabin. Both wing flaps sustained varying degrees of damage to their mounting hardware and actuation rods. The center flap remained attached and flush with the belly of the airframe. The flap actuator piston rods and the actuator control arm were in a position that corresponded to the flaps being retracted. The vertical stabilizer remained attached at its forward spar. The castellated nut on its mounting bolt was finger tight and had backed out by about 3 threads; no cotter pin was present. The wing attach points were examined for indications of corrosion-induced failure of the angle attach brackets as described in FAA Airworthiness Directive (AD) 2005-12-51. The lower angle bracket had peeled away from the center section and remained attached to the lower wing skin. All separations were observed traversing through the bolt holes, and the entire area was free of indications of corrosion. According to the airframe logbook, AD 2005-12-51 had been complied with in August 2005 with an inspection due again at 3,128.3 flight hours. The engine did not exhibit any indications of catastrophic internal failure, and cylinders Nos. 1 and 9 had detached from the crankcase in the aft direction. All spark plugs were manufactured by Champion Aerospace and were of the massive electrode type. Their plug electrodes were dark in color and exhibited wear signatures consistent with normal operation and short service life when compared to the Champion AV-27 Check-A-Plug chart. During the airframe examination, a 10-inch crescent wrench (with an opening set to about 9/16 inch), along with a 9/16-inch wrench, and a 3-inch-long 9/16-inch (head) bolt were found loose on the floor of the tailwheel strut box area, below the horizontal stabilizer main spar attach points. The rudder cables and lower elevator horn passed within the center of the box area. The errant items were well clear of (about 10 inches below) the flight controls, and no bolts were found to be missing in the tail section. The closest weather reporting station was located at Astoria Regional Airport, Astoria, Oregon, about 5 miles southwest of the accident location. An automated report issued at 1455 indicated wind from 190° at 13 knots gusting to 24 knots and variable between 160° and 230°; visibility 10 miles; light rain beginning at 1421; scattered clouds at 4,500 ft, broken ceiling at 5,000 ft, and an overcast ceiling at 6,500 ft; temperature 11°C; dew point 7°C; and altimeter 30.20 inches of mercury. By 1555, the visibility had reduced to 4 miles with light rain, scattered clouds at 2,400 ft, and an overcast ceiling at 3,100 ft. The closest weather reporting station to the primary intended ash dispersal location was Bowerman Airport, Hoquiam, Washington, about 10 miles east of Ocean Shores. An automated report issued at 1453 indicated wind from 150° at 22 knots gusting to 25 knots; visibility 4 miles; light rain beginning at 1415; mist; scattered clouds at 1,600 ft, broken at