Aeronca 7BCM N2588C accident near Lake Mcmurray, Washington

Probable cause

The pilot’s decision to continue visual flight into an area of instrument meteorological conditions, which resulted in a loss of visual reference and subsequent controlled flight into terrain.

NTSB analysis

The pilot was enroute conducting a visual flight rules (VFR) flight at a low altitude. It is likely given the weather conditions and PIREPs that low ceilings obscured the trees and high terrain from the pilot and resulted in a controlled flight into terrain.

While the closet METAR reported cloud ceilings above 1,000 ft above ground level (agl), the PIREPs and a sounding analysis program indicated that the ceiling of the clouds was about 300 ft agl near the high terrain. The accident flight likely encountered instrument meteorological conditions and mountain obscuration conditions as the flight approached higher terrain.

The pilot’s autopsy revealed significant multivessel atherosclerotic coronary disease with 80-90% narrowing of the left main and left anterior descending coronary arteries, a significant restenosis of a left anterior descending coronary artery stent, and more than 95% narrowing of the right coronary artery. The heart muscle had an area of scarring in the posterior left ventricle and interventricular septum consistent with an old injury from insufficient blood flow. Microscopic examination of the coronary system did not identify any acute clot or plaque rupture. In the autopsy report, the pathologist noted that the pilot’s family had indicated that the pilot had no new health complaints in the weeks before the accident.

Due to his heart disease, the pilot was at significantly increased risk of a sudden distracting, impairing, or incapacitating cardiac event, including angina, arrhythmia, or heart attack. There is no forensic evidence that such an event occurred. However, such an event cannot be excluded by forensic evidence alone. Given the available information about the circumstances of the crash, distracting or otherwise impairing symptoms such as chest pain or palpitations cannot be excluded. This pilot may have experienced a physiologic stress response to the poor weather conditions under which he was flying. A normal stress response would have included increased heart rate, an increase in blood flow demand from his heart, and increased respiratory rate. Physiological stress has been associated with an increased risk of cardiac symptoms such as chest pain or palpitations, most notable in patients with pre-existing cardiac disease. Thus, whether the pilot's heart disease contributed to the crash could not be determined.

Text from the NTSB. Open the NTSB docket for WPR22FA255 for the full record.