Amateur-built RV-4 N2626C accident near Oregonia, Ohio

Probable cause

The pilot's decision to fly at a low altitude, which resulted in the collision with a zipline.

NTSB analysis

The private pilot and passenger in the experimental, amateur-built airplane were seen flying at low altitude by several witnesses in various locations before the accident. The witnesses reported the engine was operating before the airplane descended into trees. Postaccident examination of the airplane, wreckage path, and a nearby zipline revealed damage consistent with the outboard section of the right wing having contacted the 1/2-inch galvanized zipline cable. There were no mechanical malfunctions or anomalies with the airplane or engine.

The cable ran between wooden platforms on the east and west sides of a river about 170 ft above ground level. The location of the platforms in wooded areas and the fact that the cable was unmarked likely made the zipline difficult to see. Witness statements and the accident scenario indicate the pilot operated the airplane at extremely low altitudes throughout the flight.

Toxicological testing of the pilot was positive for ethanol and tetrahydrocannabinol (THC, the primary psychoactive substance in marijuana). The blood level of ethanol was below the regulatory limit; however, pilots may be impaired below this threshold. The finding of THC indicated that the pilot had used marijuana sometime before the accident; however, since there is no accepted relationship between blood levels and degree of impairment, whether the impairing effects of THC contributed to the accident could not be determined.

Text from the NTSB. Open the NTSB docket for CEN17FA016 for the full record.