Imnaha, OR, USA
N9169G
Cessna 182
The pilot and three passengers were making an intermediate stopover at a mountain airstrip to camp with his family. They overflew the destination airport, and the pilot did not observe any concerns, but after they landed at the airport, the airplane became lodged in soft dirt. After several hours, they freed the airplane and decided to return to the airport they had departed from that morning. The pilot stated he felt the airplane begin to lift off the ground early during takeoff, so he maintained a nose low attitude to build up airspeed before starting a climb. When the airplane reached midfield, the pilot suddenly felt the airplane slow down and assumed the landing gear had contacted the runway. He wanted to abort the takeoff, but instead decided to fly the airplane as it had suddenly started to climb. Nearing the end of the runway he shoved the yoke forward after he heard the stall warning horn, but the airplane rolled to the right and impacted the ground. The pilot reported no preimpact mechanical malfunctions or failures with the airplane or engine that could have precluded normal operation. Contrary to the pilot’s recollection of events, flight data showed the airplane pitch increased excessively during the takeoff and the initial climb, and engine power decreased to about idle power as the airplane rotated, continued to climb, and airspeed decreased below stall speed. The stall warning horn likely engaged about the time the airplane’s critical angle of attack was exceeded, resulting in an aerodynamic stall and subsequent impact with terrain. Performance computations for the accident flight were consistent with the pilot’s, which suggested the airplane had sufficient takeoff distance to depart the runway, despite a high-density altitude. Weight and balance computations showed that the airplane was not over gross weight or outside of center of gravity limitations but that it was in a state of forward center of gravity at the time of the accident. The forward center of gravity would have resulted in a nose-heavy condition that required additional back pressure to maintain control during takeoff. The investigation did not find any evidence to suggest the airplane “slowed” during takeoff as the pilot suggested, but a wet patch on the runway or natural obstacles such as small rocks could have been present and adversely affected the takeoff roll. The accident pilot was likely fatigued after working for several hours to free the airplane from being lodged in soft dirt. This factor, coupled with stress and the pilot’s reported self-induced pressure to depart the airport, may have impaired the pilot’s judgment and decision making, causing him to overlook some of the risks associated with this departure. The fatigue likely also affected his ability to properly respond during the takeoff attempt.
HISTORY OF FLIGHTOn June 23, 2020, about 1941 Pacific daylight time, a Cessna 182N, N9169G, was substantially damaged when it was involved in an accident near Imnaha, Oregon. The private pilot and front seat passenger was seriously injured, and the two rear-seat passengers were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that he had visited several backcountry airports with his family during a planned cross-country flight in their personal airplane. On the morning of the accident, they departed their originating airport with the expectation of landing at one of three potential airports they had selected to camp overnight. The first airport was not equipped with a runway of sufficient length, so they flew to Memaloose USFS Airport (25U), Imnaha, Oregon. They decided to land after they overflew the airport and were satisfied with the field conditions. The pilot performed a soft field landing uphill on runway 17, but, during the landing roll, the right main landing gear became lodged in wet terrain. They subsequently spent several hours freeing the airplane from the soft dirt, so they decided to depart 25U as nighttime conditions were setting in and the outside air temperature was becoming colder. The pilot positioned the airplane at the departure end of runway 35 to prepare for a downhill departure into the wind. He walked the runway and did not find any foreign object debris or soft terrain along the centerline. Additionally, his preflight inspection of the airplane and subsequent engine run-up were uneventful. Prior to the takeoff roll, he deployed 20° of wing flap, set “aft” trim, and used full-up elevator, as was his custom, because the airplane was “nose heavy.” During takeoff, the pilot felt the airplane begin to lift off the ground prematurely, so he maintained a nose-low attitude to build up airspeed before starting a climb. When he reached midfield, the pilot suddenly felt the airplane slow down and assumed the landing gear had contacted the runway. He wanted to abort the takeoff but instead decided to fly the airplane as it had suddenly started to climb. Nearing the end of the runway the pilot shoved the yoke forward after he heard the stall warning horn. The airplane rolled to the right and impacted the ground. The pilot reported no preimpact mechanical malfunctions or anomalies with the airplane or engine that could have precluded normal operation. Photographs provided by a first responder showed substantial damage to the wings, fuselage, and empennage. Data was retrieved from the airplane’s panel-mounted Garmin G3X, a global positioning system (GPS) based flight display, that correlated to the accident flight and the previous flight. Engine data correlating to the accident flight was also captured by the airplane’s panel mounted JPI instruments engine data monitor (EDM-900). According to the data, the airplane made one overhead pass of 25U and landed on runway 17 about 1217. The data showed that the airplane began an attempted takeoff roll on runway 35 at 1940:22. During the beginning portion of the takeoff roll, the engine remained steady at 2,650 rpm, indicated airspeed increased, and the values for the airplane’s pitch attitude increased simultaneously. Twenty-five seconds into the ground run, the airplane’s indicated airspeed reached a maximum of 40 kts, pitch attitude was +16º, and engine rpm began to decrease. About 2 seconds later, the airspeed had decreased to 34.5 KIAS, pitch was about 22° nose high, altitude reached a maximum height of about 22 ft agl, and engine rpm was about 625. The remainder of the data is consistent with the airplane descending in a right turn with the engine operating at 625 rpm. The pilot opined that he may have become fatigued during the effort to free the airplane from the soft terrain and questioned if his desire to help his family by leaving 25U resulted in a self-induced pressure that caused him to overlook some of the potential risk factors associated with the departure. He reported no preimpact mechanical anomalies or malfunctions that could have precluded normal operation. METEOROLOGICAL INFORMATIONThe density altitude at the time of the accident was computed using the recorded data from the JPI and Garmin instruments combined with meteorological data. According to the calculations, given an outside air temperature of 23° C, a field elevation of 6,708 ft mean sea level, a pressure altitude of 6,405 ft, and a barometric pressure of 30.05 inches of mercury, the density altitude at the time of the accident was 9,155 ft. The reported sunset on the day of the accident was 2055 and dusk began at 2131. The sun’s position at the time of the accident was about 7° above the horizon on an azimuth of 295°. ADDITIONAL INFORMATIONWeight and Balance and Takeoff Performance Weight and balance calculations using data provided by the pilot indicate the airplane was loaded to 2,692 lbs at the time of the accident in a predominantly forward center of gravity (CG) but within limitations. The airplane’s maximum gross weight for takeoff was 2,950 lbs. Performance calculations computed using the meteorological conditions and airplane configuration at the time of the accident indicate the airplane would have required about 2,200 ft of runway to takeoff and clear a 50 ft obstacle. According to the POH, the airplane’s stall speed in the pilot’s takeoff configuration at the time of the accident with 20° wing flaps and 250 lbs heavier than the airplane’s takeoff weight was 51 kts (shown in POH as 59 mph) calibrated airspeed. The POH included an airspeed correction table that provided select calibrated airspeeds along with their respective indicated airspeeds. The table showed that 49 kts (shown in POH as 57 mph) calibrated airspeed was derived from 34 kts (40 mph) indicated airspeed with 20°-40° of wing flaps deployed. According to the Federal Aviation Administration Pilot’s Handbook of Aeronautical Knowledge (FAA-H-8083-25B), “A forward CG location increases the need for greater back elevator pressure. The elevator may no longer be able to oppose an increase in nose-down pitching. Adequate elevator control is needed to control the aircraft throughout the airspeed range down to the stall.” According to Dr. Stanley Trollop and R. Richard Jensen, in their book Human Factors in General Aviation, A common effect of excessive stress is fixation or tunnel vision, where you focus on one problem to the exclusion of others. You lose your ability to see all the information in front of you, making it difficult or impossible to make sound choices from the available alternatives.
The pilot’s excessively high pitch attitude and failure to maintain adequate airspeed during takeoff, which resulted in an exceedance of the airplane’s critical angle of attack and impact with terrain. Contributing to the accident was the pilot’s fatigue and his incomplete actions to abort the takeoff.
Source: NTSB Aviation Accident Database
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