CEN15LA183 · Beech 35

**This report was modified on August 7, 2020. Please see the docket for this accident to view the original report.**

The commercial pilot and three passengers were departing in the single-engine airplane from a 3,000-ft-long grass runway. The pilot reported that he thought that the windsock showed light and variable winds, but a nearby airport reported gusting wind conditions about the time of the accident. He considered taking off downhill toward a lake, but because of the possibility of a tailwind after passing the tree line, he chose to do a soft field takeoff uphill. The airplane lifted off at an indicated airspeed of 80 mph. As it neared the departure end of the runway, the pilot noticed that the airplane was not climbing as expected, the indicated airspeed seemed unreliable, and the controls felt mushy and near stall speed. Witnesses stated that the airplane traveled about halfway down the runway before it became airborne. One witness stated that he didn't think the engine speed was right and that the airplane was gaining altitude slowly. The other witness reported that the airplane wasn't gaining any altitude and that the engine sounded "strong," and did not cut out. The airplane collided with trees and a building just beyond the runway before impacting terrain. An examination of the airplane did not reveal any pre-impact abnormalities.

Given the pilot's reported weight and the weight of the 28 gallons of fuel that the pilot reported were onboard, the airplane had a remaining useful load of 379 lbs to account for the 3 other passengers. Therefore, it is likely that the airplane was operating at or near its maximum gross weight at the time of the accident. With the additional factors of an upsloping, grass runway, the airplane's performance would have been degraded and the takeoff distance required would likely have been significantly increased.

Although the pilot's operating handbook for the airplane did not contain information about takeoff performance from unpaved runways, Federal Aviation Administration (FAA) guidance states that any surface that is not hard and smooth increases the ground roll during takeoff due to the inability of the tires to roll smoothly along the runway. FAA guidance also states that the effect of an airplane's gross weight on takeoff distance is significant. Increased gross weight produces several effects on takeoff performance, including higher lift-off speed, greater mass to accelerate, and an increased retarding force (drag and ground friction). According to the airplane's takeoff distance chart, at its maximum gross weight and the atmospheric conditions at the time of the accident, the airplane would have required a ground roll of about 800 ft and a takeoff distance of about 1,400 ft to clear a 50-ft obstacle at the end of the runway. Additionally, the density altitude was about 2,249 feet. Although the exact point of rotation from the runway could not be determined, witnesses reported the airplane lifted off after traveling about 1,500 ft—much longer than the ground roll estimate in the airplane's takeoff distance chart. Even with the extended ground roll, the airplane should have been capable of climbing well above the 40 to 80 ft trees at the end of the runway in the 1,500 ft remaining after liftoff if it had been within its maximum gross weight limits. It is possible that, as the airplane approached the tree line with no margin for error in altitude, the wind gust reported by the pilot could have affected the airplane's ability to maneuver when it was so close to the trees, resulting in the impact. Ultimately, however, the pilot's decision to takeoff without accounting for the effect of the runway condition and the airplane's high gross weight and high density altitude on takeoff performance resulted in a long takeoff ground roll, reduced climb capability, and impact with trees at the end of the runway in gusting wind conditions.

Verbatim NTSB analysis and probable cause from the NTSB dataset