(WBIR) Investigators have determined a National Guard helicopter's hard landing in West Knoxville was caused by pilot error.

The incident happened on the evening of Friday, December 13.

According to Randy Harris, Tennessee National Guard's director of public affairs, one of the pilots accidentally made a "reduction of engine RPM" during a training exercise. The pilots weren't able to correct the mistake and the Kiowa OH-58 helicopter made a hard landing near Yarnell Road and Carmichael.

The pilot and an instructor, who was serving as co-pilot, were injured in the crash and transported to the hospital with minor injuries.

In addition, the investigation found the pilot's use of night vision goggles, and what was described as an "increased operational tempo due to impending deployment and compressed training time," also contributed to the incident.

Harris said investigators chose not to discipline the pilots, but instead recommended additional training in aircraft and blind cockpit operations.

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