Boeing A75L3 accident near Yacolt, Washington, September 6, 2024

The NTSB's narrative final · quoted from the NTSB record

The accident airplane was one of three airplanes traveling together on a cross-country flight. The pilots of the accident airplane and one of the other two airplanes chose to divert from the group’s typical route of flight to fly an alternate route through rising, mountainous terrain. As the two airplanes approached an area of higher terrain and a ridgeline that required a climb, the pilot of the second airplane flying the alternate route initiated a circling climb to gain sufficient altitude needed to cross the approaching ridgeline. He then continued on toward the intended destination, unaware that the accident airplane was not behind his airplane. When approaching the same ridgeline, the pilot of the accident airplane maintained an altitude that was lower than the elevation of the ridgeline and did not initiate a climb. The airplane maintained an altitude of about 2,900 ft mean sea level (msl) until it entered a left turn, followed by a rapid descent above the accident location. The airplane’s ground speed had slowed to 40 kts at the onset of the rapid descent and the left turn began about .63 statute miles from terrain that rose to 3,550 ft msl, which was the lowest available terrain ahead of the airplane’s position. The pilot likely initiated a left turn away from rising terrain and exceeded the airplane’s critical angle of attack. The investigation was unable to determine why the pilot did not initiate a climb earlier in the flight. The pilot of the second airplane flying the alternate route reported that “it wasn’t too smooth out,” which was consistent with terrain-induced wind and/or turbulence. He reported that at the initiation of his climb he added engine power, saw his ground speed decrease and then added additional engine power. He subsequently chose to circle climb to clear the ridgeline. The calculated density altitude near the accident site was 4,626 ft. Postaccident examination of the engine and airframe revealed no evidence of preaccident malfunction or failure.

The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.

Photographs from the investigation 7 pictures from the NTSB's docket, as the NTSB released them

Photograph 1 – Main wreckage at accident site.Photograph 2 – Main wreckage at accident site.Photograph 3 – Main wreckage at accident site.Photograph 4 – Propeller blade partially dug out at accident site.Photograph 5 – Main landing gear assembly.Photograph 6 – Engine at follow up examination.Photograph 7 - Engine at follow up examination.

The NTSB's photographs with the NTSB's captions, at screen size. Open a picture to see it full size or to report one that should not be shown.