2021 Cessna 206 Mountain Accident in Idaho (N922MA)

Accident Overview and Flight History On August 28, 2021, at approximately 1316 mountain daylight time, a Cessna TU206F, registration N922MA, was substantially damaged in an accident near Bernhard, Idaho. The aircraft was operating as a Title 14 Code of Federal Regulations Part 135 nonscheduled charter flight. Both passengers were fatally injured, and the pilot sustained serious injuries. The flight was a scenic tour arranged by one passenger to scout fishing locations. Flight data from an Appareo Stratus 3i GPS device indicated the aircraft departed McCall, Idaho, at 1232. It climbed to approximately 8,800 feet mean sea level (msl) before descending into the canyons of the Frank Church Wilderness. The aircraft overflew Soldier Bar Airport at 1309 and continued east for about 3 nautical miles before turning south. The pilot later recalled that the passengers wanted to return home, prompting him to search for a drainage leading back toward McCall. At 1312, he identified a suitable drainage and turned west while climbing, intending to overfly the mountain peaks at the end of the drainage. As the aircraft approached the ridge line, the pilot moved from the right side of the drainage to the left. He determined the rate of climb was insufficient to clear the peak and initiated a 180-degree turn to gain altitude. The aircraft slowed to about 62 knots groundspeed during the climb. The pilot reported encountering a downdraft after starting the turn, which caused a rapid descent despite full power and full propeller rpm. He recalled extending the wing flaps but could not remember when, stating he would not have extended them fully. He described “riding the edge of stall into the trees because I had nowhere to go,” with the stall warning horn sounding intermittently. In the final two minutes of recorded data, the aircraft climbed from about 7,000 feet to 8,300 feet. Pitch attitude exceeded 10 degrees nose-up for much of the final minute, reaching a maximum of 17 degrees nose-up about 5 seconds before the data ended. Speed remained below 80 knots during the final minute, dropping below 65 knots in the last 15 seconds. The flight track ended at an altitude of 8,397 feet msl with a groundspeed of about 55 knots, approximately 90 feet from the accident site. A 406 MHz emergency locator transmitter signal was received at 1318, and the wreckage was located about 1646. ## Personnel and Training The pilot was an experienced military fighter jet pilot with extensive low-level flight training, though this was his first scenic flight. He had completed multiple charter flights between destinations prior to the accident. He reported becoming familiar with the Cessna 206 in May 2021 and completed most of his training in the accident aircraft with the director of operations of McCall Aviation. Training included basic flight characteristics, approach turn stalls, and regular stalls. They performed local flights to nearby airfields such as Donnelly and New Meadows. The pilot described the training as “pretty thorough for general aviation,” with each flight accompanied by a one-hour brief and debriefing. During training, they did not fly into drainages, but the director of operations used nearby peaks to demonstrate proper mountain flying techniques, including finding updrafts on one side of a ridge. That summer, the pilot flew the Cessna 206 into small airfields within the Frank Church Wilderness. He frequently followed other airplanes during group flights to observe their movements and stated that by the time of the accident, he had flown in and out of drainages multiple times by himself in the accident aircraft make and model. Operator records showed the pilot was signed off to fly the accident aircraft on June 14, 2021. On the day of the accident, he departed on a charter flight to Salmon, Idaho, at 0640 and returned about 1025. ## Meteorological Information Another charter pilot who flew to an airfield about 43 nautical miles east of the accident site on the morning of the accident reported weather conditions were “beautiful” with light wind. An unofficial weather station about 8 miles north of the accident site at an elevation of 4,575 feet msl recorded a temperature of 75°F, dewpoint 37°F, wind from 050° true, sustained wind magnitude of 2 mph, and wind gust magnitude of 7 mph. A high resolution rapid refresh (HRRR) model for the accident location at 1300 indicated various temperature and density altitude conditions at different heights. A review of Graphical Turbulence Guidance showed some light mountain wave activity in Colorado and southeastern Idaho between 7,000 and 11,000 feet at the time of the accident. The graphical forecast did not show evidence of eddy dissipation in the Frank Church Wilderness. A pilot with about 13 years of experience flying the Idaho backcountry and familiar with the accident area noted that he typically worried about downdrafts when wind reaches about 25 knots at 9,000 feet, but reported that mechanical downdrafts can also occur at lower wind speeds. ## Wreckage and Impact Information The aircraft was located on the east side of a mountain in the Payette National Forest at an elevation of about 8,370 feet msl, approximately 1,000 feet below the mountain’s peak. The initial point of impact was marked by an approximate 60-foot-tall tree severed at the top, located 120 feet from the main wreckage. A 50-foot-wide debris path oriented on a northwesterly heading was identified by several broken trees between the initial impact point and the main wreckage, consistent with impact with terrain while in level flight. A portion of the right wing was located in the debris path a few feet from the main wreckage, which comprised the rest of the airplane. The aircraft was oriented on an easterly heading, and all major components were accounted for at the accident site. Postaccident examination of the wreckage did not reveal any preimpact mechanical anomalies that would have precluded normal operation. Flight control continuity was traced from the cockpit controls to the aileron, elevator, and rudder control surfaces. Both the elevator control cables and the rudder cables were cut by recovery personnel. The right aileron direct cable exhibited signatures consistent with overload separation. The elevator trim tab had separated from the horizontal stabilizer; however, the actuator measured outside the normal operation range in the tab trailing end up deflection. The flap actuator position was consistent with the flaps in the near full down position, which was also consistent with the indications at the flap handle and flap position indicator. Examination of the engine established mechanical continuity throughout the rotating group, valve train, and accessory section as the crankshaft was manually rotated by hand at the propeller. The magnetos produced spark at all six plug leads, and most spark plugs displayed signatures consistent with normal wear, except for three spark plugs that had some evidence of oil. Examination of interior components, including cylinders, pistons, and valves using a lighted borescope, revealed no indications of catastrophic engine failure. ## Additional Information Performance calculations using the pilot’s operating handbook (POH) indicated that, under normal operating limitations at a maximum weight of 3,300 pounds and an airspeed of about 95 knots, the aircraft would have required about 5 minutes to climb from 6,000 feet msl to 9,000 feet msl. Factoring in an additional 15% to adjust for temperature, which was about 11 degrees warmer than standard, the aircraft would have required about 5 minutes 45 seconds to make the climb. According to flight data, the accident occurred about 4 minutes and 5 seconds after the pilot began climbing from 6,000 feet msl. The terrain elevation at the bottom of the drainage increased from about 4,000 feet msl when the aircraft turned into the drainage to about 8,000 feet msl when the aircraft began to descend over the course of about 6 nautical miles. From the point of descent to the top of the lowest peak, elevation increased about 1,000 feet over the course of about 0.6 nautical miles. In addition to practical training, the pilot attended company training in May 2021, which included a presentation on mountain flying. Subjects covered included “Clearing Mountains” and “Course Reversal.” The “Clearing Mountains” section contained guidance on having an “escape route” and selecting a canyon, including always remaining in a position where you can turn toward lowering terrain and not flying beyond the point of no return. The pilot stated that his escape route was “simply to turn around” and that he did not remember having selected a point to abort when flying up the drainage. The “Course Reversal” section included guidance on making a 180-degree turn, including slowing down to decrease the radius of turn, pulling back on the control wheel to trade airspeed for altitude if extra speed was available, and making the steepest turn comfortably possible, up to 60 degrees. According to the pilot’s operating handbook, the stall characteristics are conventional and aural warning is provided by a stall warning horn which sounds between 5 and 10 knots above the stall in all configurations.