CEN14GA135

The pilot’s improper decision to fly into an area with reported marginal meteorological conditions in an airplane not maintained for instrument flight and his subsequent failure to maintain clearance from trees and terrain.

The commercial pilot departed on a fire detection flight for a state fire commission using a predetermined flight route. The pilot was receiving flight-following services from the dispatch center and was reporting his flight progress to a dispatcher. The pilot reported entering the eastern boundary of the forest district and then turning north toward the next checkpoint. Five minutes later, the pilot reported that he was turning back due to low cloud ceilings. About 14 minutes later, the airplane impacted trees on a ridgeline, which had an elevation of 1,473 ft, and the main wreckage was located 0.3 mile south of the ridgeline. A postaccident examination of the airframe and engine revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation. Examination of the propeller revealed damage consistent with a medium-to-high power setting at impact. Although the airplane was equipped and certificated for flight in instrument meteorological conditions, the instruments required for instrument flight were not maintained to those standards; therefore, the airplane was limited to flight in visual flight rules conditions only. Surface weather reports indicated low cloud ceilings of 700 to 1,100 ft above ground level along most of the route of flight. Wave clouds and associated turbulence also existed in the area about the time of the accident. A surface weather reporting station located 21 nautical miles west of the accident site and within the planned route of flight was reporting clouds overcast at 500 ft at the time of the accident. The fire commission's aviation department did not use flight risk assessments. No record was found indicating that the pilot received a preflight weather briefing; however, it could not be determined if the pilot obtained weather information using other sources. Toxicological testing detected nortriptyline, which can be impairing, in the pilot's liver; however, no evidence was found indicating that the nortriptyline impaired his decision-making or flying skills at or around the time of the accident.

The engine was examined at Continental Motors on May 6, 2014, under the oversight of the National Transportation Safety Board. The examination of the engine revealed that the engine crankcase and cylinders were intact, but exhibited thermal damage consistent with the ground fire. The power section of the engine, which included the crankshaft, camshaft, connecting rods, and pistons, was intact with no indication of internal heat distress or preexisting mechanical damage. The spark plugs exhibited normal wear signatures. The engine accessories exhibited impact and thermal damage consistent with ground impact and ground fire. The autopsy of the pilot was conducted on February 13, 2014, at the Arkansas State Crime Laboratory in Little Rock, Arkansas. The "cause of death" was noted as "multiple injuries" as a result of an aviation accident. A Forensic Toxicology Fatal Accident Report was prepared by the FAA Civil Aerospace Medical Institute. The results were negative for ethanol, and the tests for carbon monoxide and cyanide were not performed. The toxicological report indicated that nortriptyline was detected in the liver. Nortriptyline is a medication used to treat depression and chronic pain marketed as Pamelor. It carries the warning "may impair mental and/or physical ability required for the performance of potentially hazardous tasks (e.g., driving, operating heavy machinery). According to the FAA medical certification file, the pilot had chronic knee pain treated with acetaminophen and unspecified non-steroidal anti-inflammatory drugs. The FAA designated aviation medical examiner (AME) determined the knee pain did not impair the ability of the pilot to safely operate an airplane and issued a medical certificate without limitations. Personal medical records revealed the pilot had chronic knee pain that was treated with tramadol, meloxicam, and an increasing dose of nortriptyline. The autopsy was limited due to extensive injuries but found no evidence of natural disease. The airplane initially hit the tops of trees near the top of the ridgeline, which had an elevation of 1,473 feet, located in a remote forest with steep, rugged terrain. The outboard 8 foot section of the left wing separated from the airplane with fracture surfaces consistent with overload, and was found near the top of the ridgeline. The main wreckage was located 0.3 mile south of the ridgeline at an elevation of 686 feet on a 175 degree magnetic bearing. The airplane's engine and propeller, right wing, the remaining section of the left wing, fuselage, and empennage were all located at the main wreckage site which was found on the side of another wooded ridge. A ground fire had consumed much of the nose compartment, instrument panel, cockpit, and cabin. The wings and empennage exhibited aft crushing and buckling which was consistent with a steep, nose down impact with terrain. Control cable continuity was established for the rudder and elevator control surfaces. The aileron control cable was attached at the cockpit yoke and aileron attach points, and all the cable separations were consistent with overload failures. The engine was shipped to the engine manufacturer for a teardown examination. The propeller remained attached to the engine, but one of the propeller hub sockets was fractured and the propeller blade, blade retention nut, steel blade ferrule, and bearing assembly were not recovered. The fracture surface of propeller hub was consistent with overload. The examination of the recovered propeller blade revealed that it exhibited blade bending and twisting. The leading edge of the blade had gouges and notches along with chordwise scarring of the blade surface. The National Weather Service Surface Analysis Chart depicted a frontal boundary that stretched from northern Texas northeastward across northwestern Arkansas and into southern Indiana. A surface low pressure center was located in central Oklahoma. A surface high pressure center was located in eastern Alabama. The accident site was located in a favorable area for clouds given the proximity of the frontal boundary and low pressure center as both of these features could act as lifting mechanisms. There is no aviation weather reporting station located at M78. The 1153 surface weather observation at the Hot Springs Memorial Field Airport (HOT), Hot Springs, Arkansas, located 35 nm miles on a 082 degrees magnetic bearing from the accident site, at an elevation of 540 feet, was wind 150 degrees at 4 knots; 10 miles visibility; overcast 1,500 feet; temperature 10 degrees Celsius (C); dew point 5 degrees C; altimeter 29.97 inches of mercury. The 1253 surface weather observation at HOT was wind 180 degrees at 3 knots; 10 miles visibility; overcast 1,700 feet; temperature 12 degrees C; dew point 6 degrees C; altimeter 29.93 inches of mercury. The 1153 surface weather observation at the Bearce Airport (7M3), Mount Ida, Arkansas, located 15 nm on a 041 degrees magnetic bearing from the accident site, at an elevation of 644 feet, was wind variable at 3 knots; 10 miles visibility; overcast 1,100 feet; temperature 9 degrees C; dew point 6 degrees C; altimeter 29.92 inches of mercury. The 1253 surface weather observation at 7M3 was 10 miles visibility; overcast 1,200 feet; temperature 10 degrees C; dew point 7 degrees C; altimeter 29.89 inches of mercury. The 1155 surface weather observation at the Mena Intermountain Municipal Airport (MEZ), Mena, Arkansas, located 21 nm on a 292 degrees magnetic bearing from the accident site, at an elevation of 1,080 feet, was wind light and variable; 7 miles visibility; overcast 500 feet; temperature 11 degrees C; dew point 10 degrees C; altimeter 29.92 inches of mercury. The 1315 surface weather observation at MEZ was wind 170 degrees at 3 knots; 7 miles visibility; overcast 700 feet; temperature 12 degrees C; dew point 11 degrees C; altimeter 29.89 inches of mercury. The National Transportation Safety Board weather specialist reported that the sounding wind profile indicated a surface wind from 120 degrees at 2 kts that increased to 27 kts by 2,000 feet above mean seal level (msl) with the wind from the southwest. Given the rapid increase in wind speed with height between the surface and 2,000 feet, low-level wind shear (LLWS) and clear air turbulence would be expected. The wind above 2,000 feet remained out of the southwest to west while increasing in speed to 65 knots by 15,000 feet. Satellite data indicated areas with visible wave clouds oriented east to west near the accident site at the time of the accident. LLWS and clear air turbulence would most likely be concentrated in the areas of the wave clouds. The AFC aviation manager indicated that the pilot routinely called 1-800-WX-BRIEF for his weather. There is no record that the pilot called 1-800-WX-BRIEF or received information from DUAT/DUATs on the day of the accident. In addition, the AFC indicated that their pilots will occasionally check weather conditions on the WeatherTAP website. The recorded data from the website indicated which WeatherTAP products were viewed by individuals at the AFC before, during, and after the accident time. However, there is no way to know which individuals reviewed the WeatherTAP products during that timeframe, because all the individuals use the same login information for the WeatherTAP products. All of the WeatherTAP products listed were regional or state scale satellite and radar images. The AFC did not use flight risk assessment forms prior to each flight. There is no record of the accident pilot receiving or looking at weather information before the flight. Two AFC pilots were conducting fire surveillance flights around the time when the accident occurred. One of the pilots departed M78 about 1310 and flew a fire detection flight in north central Arkansas, which is north and west of Little Rock, Arkansas. He reported that the weather was overcast with 5 to 15