What happened
On October 7, 2014, at approximately 1623 Pacific daylight time, a Marsh Aviation S-2F3AT aircraft, operating as "Tanker 81," crashed while performing a firefighting mission in Yosemite National Park near El Portal, California. The aircraft, registration N449DF, was part of a public firefighting operation under the control of the US National Park Service.
Prior to the accident, the aircraft had departed Columbia Airport (O22) to support the Dog Rock fire. After completing one successful fire retardant drop and reloading at O22, the pilot returned to the fire area. The flight was supported by an Air Tactical Ground Station (ATGS) and an Aerial Supervision Module (ASM) aircraft, which acted as a lead plane to define the drop route.
The ASM pilot flew the proposed route, using smoke to indicate the drop location and providing instructions to avoid a specific tree hazard to the right of the flightpath. The ASM pilot reported that the air was smooth and visibility was good. During the approach, the aircraft struck trees with its left wing. Following this impact, the airplane entered a descending left roll and struck the top of an approximately 800-foot-tall rock cliff. The impact caused the aircraft to fragment and a fire to erupt, scattering wreckage across a river valley below.
The investigation
Investigators examined the wreckage and found that the outboard section of the left wing had separated from the aircraft. The inboard end of the separated wing section showed impact marks perpendicular to the wingspan. The wing-fold locking mechanism was found in the locked position.
An examination of both engines revealed impact signatures consistent with the engines producing power at the time of the accident. No mechanical or maintenance anomalies were found in the aircraft's logs, and the most recent 100-hour inspection had been completed in August 2014.
Findings
- The pilot was conducting a visual flight rules firefighting retardant drop.
- The aircraft struck trees with its left wing during the approach.
- The pilot sustained 1 fatal injury.
- The aircraft was destroyed.