LAX06GA287

The airplane impacted rising mountainous terrain in a box-like canyon while performing mission-related low altitude aerial surveillance. The pilot was under contract to fly California Department of Forestry (CDF) personnel over an area where three fires had occurred and to search for newly developing fires. During the 14-minute-long flight, the pilot proceeded to the designated area and commenced providing his observer-crewmember with a viewing opportunity. The pilot flew up and down the canyon's drainage area, which was surrounded by higher elevation terrain. Witnesses initially observed the airplane flying 1,000 to 1,500 feet above ground level (agl). Subsequently, the airplane was observed flying 100 to 150 feet agl. Seconds before the crash, a witness located 3/4-mile downslope from the accident site observed the airplane proceeding over progressively higher elevation terrain while flying between 400 to 600 feet agl, and with its nose pitched upward at a 40-degree angle. Another witness about 1/2-mile downslope from the accident site reported hearing airplane engine noise consistent with high rpm, the sound of a crash, and the sound of a falling tree followed by an explosion. The airplane impacted 125-foot-tall trees on 25- to 40-degree upsloping terrain, fragmented, and was destroyed by the post impact fire. Wreckage from the airframe and all six propeller blades were examined on the 6,240-foot mean sea level mountainside. The turboprop engines were subsequently recovered and torn down. A plethora of evidence was found consistent with rotational operation at high power followed by sudden stoppage. No evidence of any preimpact airframe or engine malfunction was observed. CDF had published a restriction specifying that the accident airplane not be flown lower than 500 feet agl during missions. The restriction document was found in the airplane wreckage. Additionally, CDF had not authorized the pilot to fly missions at any time below 500 feet agl.

History of flight

On September 6, 2006, about 1039 Pacific daylight time, a North American Aviation, Inc., OV-10A, N419DF, (call sign "Air Attack 410") impacted trees and rising mountainous terrain while maneuvering about 25 statute miles northeast of the Porterville Municipal Airport, Porterville, California. The accident occurred in the Mountain Home Demonstration State Forest (MHSF). The United States Forest Service and the State of California Department of Forestry & Fire Protection (CDF) owned the airplane, which was operated by CDF during the public-use flight. The airplane was destroyed during the impact sequence and post impact ground fire. The two occupants, an airline transport certificated pilot and an observer-crewmember, were fatally injured. No one on the ground was injured. Visual meteorological conditions prevailed. CDF management reported that the flight was conducted under the provisions of 14 CFR Part 91, and it was dispatched in accordance with the department's flight following procedures. The accident flight commenced from Porterville at 1025.

On the day of the accident and during several preceding days, three fires existed near the MHSF. The CDF's airborne mission involved using air attack (reconnaissance) airplanes and air tankers (fire retardant droppers) to address the fires.

Air Attack 410's mission was to provide tactical coordination and communication with the incident commander (IC) on the ground. The information that the crew gathered was related to evaluating the status of the previously observed fires, and identifying the onset of new fires including providing information regarding their respective spread.

CDF management reported to the National Transportation Safety Board investigator that during the flight the accident airplane was operating pursuant to its prescribed mission in the air attack capacity by flying within the MHSF and adjacent areas. The accident OV-10A was the only CDF airplane flying in the area.

The pilot was an employee of DynCorp, McClellan, California, and was working under contract for CDF. The observer-crewmember was a CDF battalion chief and was working as the air tactical group supervisor (ATGS).

After the pilot received his duty assignment and signed the CDF's flight release document, he proceeded to preflight the airplane. The ATGS similarly received his duty assignment. Thereafter, both crewmembers boarded the airplane and the flight commenced.

Visual and/or auditory witnesses to the airplane's flight were situated at varying locations and elevations in the vicinity of the MHSF. No witness reported observing the final seconds of the airplane's flight and the impact sequence. The latter portion of the airplane's flight path was reconstructed from the witness statements. (The reconstructed path is included in the public docket for this accident report.)

After departure and flight in a northeasterly direction over the increasingly higher elevation terrain, the airplane was observed to perform several orbits before proceeding farther up the canyon. Witnesses reported hearing communications between the accident airplane and the IC in which the flight operation plan was discussed. One witness recalled that the crew was going to "check for smokes." Some witnesses reported that the engines were sputtering and did not sound right, while others reported hearing nothing unusual.

The airplane flew past the location of three fires referred to as the Mountain Fire, the Camp Fire, and the Jaguar Fire. Thereafter, the airplane continued flying in a northeasterly direction for an additional 1/2-mile over increasingly higher elevation terrain. Several witnesses (auditory and visual) were located near the airplane's flight path as it flew over an area known as the Bear Creek drainage.

An auditory witness, located near the Mountain Fire (about 2 miles southwest of the crash site) reported to the Safety Board investigation team that he heard the ATGS say they would fly "low and slow" while in the canyon.

An eyewitness, also located about 2 miles southwest of the crash site, reported that he observed the airplane flying 1,000 to 1,500 feet above ground level (agl) when flying down the canyon, and between 100 to 150 feet agl when flying up the canyon. This witness also reported that he heard the engine noise become louder as if the engine power was being increased.

An eyewitness located near the Jaguar Fire, about 0.75 miles southwest of the crash site, reported observing the airplane flying up the canyon 8 to 10 seconds before it crashed. This witness estimated that the airplane was between 400 and 600 feet agl, and was in a 40-degree nose up attitude.

The witness closest to the accident site was located less than 0.5-mile southwest of the site. This witness reported hearing airplane engine noise consistent with high rpm, the sound of a crash, and the sound of a falling tree followed by an explosion.

None of the eyewitnesses who observed the accident airplane flying in or near the MHSF, either up or down the drainage area, reported observing any evidence of smoke trailing the airplane. With the exception of the airplane's last few seconds of flight, none of the eyewitnesses reported observing any maneuvering inconsistent with the typical operation that they had previously observed when this model of airplane performed other surveillance flights.

Personnel information

Pilot.

The pilot held an airline transport pilot certificate, multiengine land, and he had commercial pilot privileges, airplane single engine land. He also held a certified flight instructor certificate, airplane single engine land, with an expiration date of February 2007.

The pilot's resume indicated that he had been employed as a pilot since 1981 and had principally worked for California-based companies. In April 2002, DynCorp employed the pilot. The pilot received flight proficiency checks in the OV-10A from CDF personnel.

During employment with DynCorp, the pilot had flown 670 hours of fire surveillance flights. During the 90 days preceding the accident, the pilot had flown the OV-10A for 127 hours. The pilot had been on duty for the sixth consecutive day when the accident occurred. He had not flown the day prior to the accident day, and he had flown 3 hours 2 days prior to the accident. According to the CDF participant, the pilot was in compliance with all department crew day and crew rest requirements during this time frame.

The pilot completed a flight review and instrument proficiency check in April 2006. The pilot's most recent CDF flight check was successfully completed as an air attack pilot on May 25, 2006. On this date, the pilot reported his total flight time was 12,387.7 hours, and his total pilot-in-command time flying the OV-10A was 730.6 hours. (The pilot's flight time in the OV-10A is approximated.)

CDF management reported that the pilot had completed its training program in accordance with the "Aviation Management 8300 Procedures Handbook." In pertinent part, the CDF handbook includes the following important notes in section 8362.4.1:

"Special training and pilot certification are required for fixed wing low level flight operations (flight below 500 feet AGL). Unless specifically authorized for low level operations by an inter-agency pilot inspector, pilots may not descend below 500 feet AGL, except during takeoff and landing."

"When operating within the confines of a canyon, pilots shall always make allowances for completing a 180-degree turn away from rising terrain."

On April 7, 2005, CDF issued the pilot a USDA interagency qualification identification card. On the backside of the card specific authorizations were identified that referred to the "SPECIAL MISSION" assignments the pilot was authorized to undertake. The pilot was authorized to fly the OV-10 airplane in an air attack capacity.