Amateur-built SONEX TRAINER N543SX accident near Carrabelle, Florida

Probable cause

A loss of engine power for reasons that could not be determined because the airplane was not recovered. Also causal was the pilot's decision to conduct a low-altitude turn following the loss of engine power, which resulted in an exceedance of the airplane's critical angle of attack and an aerodynamic stall.

NTSB analysis

The private pilot had been having engine issues on his single-engine, experimental, amateur-built airplane and the purpose of the flight was to test the engine. A witness heard the pilot start the airplane's engine, taxi to the runway, and depart without conducting an engine run-up. When the airplane was about halfway down the 4,000-ft-long runway, he heard the engine lose power. The witness looked up and saw the airplane about 100 ft above the runway; it then entered an "aggressive bank" to the left and subsequently stalled and descended "straight down." The airplane came to rest upright in heavily wooded and swampy terrain about 250 yards north of the airport. The airplane was not recovered from the swamp or examined, and the reason for the loss of engine power was not determined.

The pilot succumbed to his injuries after being transported to the hospital. The pilot's admission blood was submitted by the medical examiner for toxicology and the results were negative for all items tested. Postmortem toxicology identified several medications that were likely given as part of postaccident medical treatment, as well as sildenafil, diphenhydramine, and zolpidem.

Though diphenhydramine and zolpidem are impairing drugs, it is unlikely that effects from these medications contributed to the accident circumstances. Given the witness statement, it is likely that the pilot exceeded the airplane's critical angle of attack during the attempted return to the runway following the loss of engine power, which resulted in an aerodynamic stall and impact with terrain.

Text from the NTSB. Open the NTSB docket for ERA18LA083 for the full record.