On October 7, 2014, a MARSH AVIATION S 2F3AT NO SERIES (registration N449DF) operated by USDA FOREST SERVICE FEPP was involved in an aviation accident near El Portal, CA. One person was killed. Investigators recorded the probable cause as: The pilot's failure to maintain clearance from trees while maneuvering at a low altitude. This summary draws on records from NTSB; 1 related events involving the same aircraft type or operator are linked below.
On October 7, 2014, a Marsh Aviation S-2F3AT, N449DF, crashed in Yosemite National Park while conducting a firefighting drop. The pilot was killed, and the aircraft was destroyed after striking trees and terrain.
Accident Overview and Flight History On October 7, 2014, at approximately 1623 Pacific daylight time, a Marsh Aviation S-2F3AT aircraft, registration N449DF, operating under the call sign “Tanker 81,” impacted terrain in Yosemite National Park near El Portal, California. The aircraft was registered to the United States Department of Agriculture and operated by CAL FIRE, though it was under the operational control of the U.S. National Park Service for a public firefighting mission. The airline transport pilot sustained fatal injuries, and the aircraft was destroyed. Visual meteorological conditions prevailed at the time of the accident. The aircraft had departed Columbia Airport (O22) in Columbia, California, at 1608. According to a CAL FIRE representative, Tanker 81 was stationed at the Hollister, California, air base and had been dispatched to the Dog Rock fire in Yosemite National Park. The aircraft successfully completed one fire retardant drop before returning to O22 to reload. It was supported by two other aircraft: an orbiting Air Tactical Group Supervisor (ATGS) aircraft that coordinated aerial operations with ground units, and an Aerial Supervision Module (ASM) that flew ahead of the tanker to define the route and drop initiation point. Upon returning to the fire area, the pilot coordinated the next drop with the orbiting ATGS aircraft and followed the ASM. The ASM pilot flew the proposed drop route and used smoke to indicate the desired drop location. The route included a slight left turn to final and a right turn to exit over descending terrain. The ASM descended to 4,000 feet mean sea level (msl) during the run and identified a prominent tree to the right of the flightpath as a hazard, instructing the pilot to stay to the left of it. The ASM pilot described the air over the drop area as “very clear, smooth” and asked the pilot if the route looked acceptable. The pilot responded that “it looked OK.” The ASM then climbed to 5,100 feet msl to lead the drop run. The ASM pilot joined the pattern on the downwind and instructed the tanker pilot that he could descend to 5,100 feet msl. He continued to describe the drop and flightpath, noting some thin top smoke on final but stating that visibility was sufficient and that they would break out of the smoke before reaching the drop area. The last communication from the tanker pilot was an “OK” on the downwind, which the ASM pilot noted was not unusual. The ATGS crew reported that, while Tanker 81 was on final approach for the drop, it appeared to strike trees with its left wing. Both aircrews reported smoke in the area but good visibility along the approach to the drop. Witnesses observed the accident, and one provided a video taken from a mountain trail above the flightpath. The video showed that, while on approach to the drop site, Tanker 81 struck trees with its left wing. Following the impact, the aircraft entered a descending left roll and impacted the top of an approximately 800-foot-tall rock cliff. A fire erupted during the impact, the aircraft fragmented, and the main wreckage was projected over the cliff and scattered across a wide river valley area below the cliff face. Telemetry data showed the aircraft on a course heading of 253 degrees at 4,810 feet msl and 148 knots at 1623. The flight telemetry log is included in the public docket for this report. ## Personnel and Aircraft Information The pilot held an airline transport certificate with airplane multiengine land, airplane single-engine land, and instrument ratings. He was issued a Federal Aviation Administration second-class medical certificate on February 12, 2014, with the limitation that he must wear corrective lenses. His flight records showed 6,567 total flight hours. The aircraft was originally a Grumman S-2 manufactured in 1966, but it was remanufactured as a Marsh Aviation S-2F3AT in 2004. It was equipped with two Honeywell (Allied Signal) TPE331-14GR turbine engines. Total airframe time since new was 5,819.5 hours as of October 2, 2014. The aircraft was operated in the restricted category and maintained under annual and 100-hour inspections. The latest 100-hour inspection was completed on August 23, 2014. A review of maintenance logs showed no evidence of any airplane mechanical or maintenance anomalies. ## Communications, Meteorology, and Wreckage The pilot of Tanker 81 was in radio communication with either the fire base, the ATGS, or the ASM throughout the accident flight. He did not express any concerns about the flight or report any mechanical issues. At 1600, the closest official weather reporting station, about 7 miles northwest of the accident site, reported clear skies, a temperature of 75°F, a dew point of 32°F, an altimeter setting of 29.90 inches of mercury, wind from 225 degrees at 10 to 15 knots, and visibility greater than 10 miles. The aircraft impacted trees and terrain on a steep, heavily vegetated area within the active fire zone. All wreckage sustained impact and fire damage. The top of a tree had been severed and lay on the ground, and the outboard section of the left wing was found separated from the aircraft. The inboard end of the separated wing section leading edge showed impact marks perpendicular to the wingspan. The inboard end of the wing section was torn chordwise from leading edge to trailing edge. Along the chordwise tear, the sheet-metal tears were jagged, and the internal structure was pulled apart. The tear was outboard of the locking mechanism that locked the folding wing in place. The aileron and flap were in place. The main fuselage, right wing, and both engines and their associated propellers were found in the river valley area below the cliff face. The wing-fold locking mechanism for the left wing’s outboard section and the locking mechanism’s locking devices, which were found in the “locked” position, were also located in the valley. The left-wing outboard section had separated outboard of the locking mechanism. Examination of both engines revealed impact signatures consistent with their producing power at the time of impact. All propeller blades exhibited S-bending and torsional twisting. Portions of the blades were fragmented and exhibited leading edge gouging and chordwise scratching. Following the onsite examination, the wreckage was recovered to a secure facility and reexamined. No anomalies were noted with the aircraft or engines. ## Operational, Medical, and Pathological Information A review of the Interagency Aerial Supervision Guide (ASG), document PMS 505, NFES 002544, dated January 2014, Chapter 9, Tactical Aircraft Operations, outlines operational procedures for air tanker aircraft. Section 1, Low Level Operations, part b, item i defines a “show me” profile as a low-level pass made over the target using the physical location of the aircraft to demonstrate the line and start point of the retardant drop. The Show-Me Profile is normally used for the first airtanker on a specific run or when an incoming airtanker has not had the opportunity to observe the previous drop. A Show-Me can be used alone or before other profiles. The pilot of the lead plane begins the run when the airtanker crew can visually identify the aircraft, hazards, line, start, and exit point of the drop. An NTSB Operations Group was formed, and the Operations Group Chairman’s report is available in the public docket for this report. The Mariposa County Coroner in Modesto, California, conducted an autopsy on the pilot. The pilot’s cause of death was attributed to “multiple blunt force injuries.” The FAA Bioaeronautical Sciences Research Laboratory in Oklahoma City, Oklahoma, conducted toxicological testing on specimens from the pilot. No toxicological anomalies were found.