CEN15FA245

The pilot’s decision to take off ahead of an approaching severe thunderstorm, which resulted in an encounter with hazardous weather conditions that led to a loss of airplane control.

Before attempting to take off, the commercial pilot received weather information indicating that a severe thunderstorm was approaching the airport. Further, two witnesses reported seeing the storm approaching. Several witnesses reported seeing the airplane take off, make a left turn, and then head straight down. GPS data indicated that, after the airplane took off, it banked left, reached about 80 ft above ground level, and then descended and impacted terrain. One of the witnesses stated that they could not believe anybody would take off in the approaching storm. Another witness reported that she was "watching the storm clouds" and heard an engine at "full throttle" and then looked over and saw the airplane "traveling very fast" toward the ground. Examination of the airplane revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation. A postaccident review of weather information established that a gust front associated with a squall line of an approaching severe thunderstorm was over the airport at the time of the accident. This weather situation was likely producing a combination of the following weather phenomenon near the accident site at the time of the accident; strong gusting winds, turbulence, low-level wind shear, reduced visibility due to blowing dust, heavy rain, hail, and lightning. The flight encountered these hazardous conditions during initial climb, which likely made the airplane difficult for the pilot to control and resulted in his loss of airplane control shortly after takeoff. Given the pilot had the current weather information and should have been able to see the approaching storm, he should not have taken off in such conditions. The pilot's decision to take off with such hazardous weather conditions present resulted in the accident.

The South Plains Forensic Pathology, P.A., Lubbock, Texas, conducted an autopsy of the pilot. The cause of death for the pilot was attributed to "blunt force injuries of head, neck, torso and extremities." The FAA Bioaeronautical Sciences Research Laboratory, Oklahoma City, Oklahoma, performed toxicology testing on specimens from the pilot. The toxicology results were negative for all tests. The main wreckage was located in a flat, grass field about 1,100 ft southeast of runway 04/22. The airplane came to rest on a magnetic heading of 130º at an elevation of 3,609 ft. A postimpact fire had ensued. Figure 5: Wreckage Diagram Airframe The airplane impacted terrain in about a 20°-nose-down attitude. Ground scars were consistent with a near vertical impact. The ground scars were also consistent with the landing gear being extended at the initial impact; however, fire damage precluded determination of the landing gear actuator position. A propeller blade fractured at impact and separated from the crankshaft, and the hub separated from the engine's propeller flange. The remainder of the airframe continued to travel on a southeasterly heading and impacted the ground about 100 ft from the initial impact. As viewed from the initial impact point looking south, the main cabin door separated from the fuselage and came to rest left of, and about 162 ft from, the main wreckage. The separated nose landing gear was found near the initial impact point and 152 ft from the main wreckage. The separated left main landing gear (MLG) was found left of the main debris path and about 74 ft from the main wreckage. The separated right MLG was found right of the main debris path and about 90 ft from the main wreckage. The postimpact fire consumed major portions of the fuselage, empennage, and wings. The flap actuator housings were consumed by the postimpact fire, which precluded their measurement. Engine The engine was examined on-scene by the National Transportation Safety Board investigator-in-charge and an engine manufacturer representative. The engine crankcase remained intact; however, the engine sustained extensive thermal damage due to the postimpact fire. The crankshaft was rotated by hand, and continuity was established between the crankshaft, camshaft, connecting rods, and associated components. All six cylinders were examined using a borescope, and no anomalies were noted. All cylinders produced compression when the crankshaft was rotated, and all rocker arms and valves operated normally. The right and left magnetos rotated by hand and produced a spark on all six posts during impulse coupling operation. The ignition harness sustained significant impact and thermal damage; however, the ignition harness produced a spark on the upper spark plugs for the Nos. 1, 3, and 5 cylinders. The remaining ignition leads could not produce a spark, consistent with thermal damage. All spark plugs displayed normal operating and wear signatures. Thermal damage was noted on all the fuel and oil system components. There was no evidence of mechanical malfunctions or failures that would have precluded normal operation. The separated propeller sustained significant impact damage. All the propeller blades displayed leading-edge polishing, chordwise scratches, leading-edge gouging, and twisting deformation consistent with being under power at the time of impact. At 2058:58, the pilot filed an IFR flight plan on, and received weather information from ForeFlight.com. The weather information included conditions at the destination airport; the latest TAF; the latest METARs, SIGMETs, and AIRMETs along the flight route; notices to airmen; current severe thunderstorm watch and warning information; area forecasts; the convective outlook; PIREPs, and winds aloft information. Portions of that information are discussed below. For more weather information, see the Weather Study in the public docket for this accident. The closest official weather station was PVW, located 1 mile from the accident site at an elevation of 3,374 ft msl. At 2055, the PVW Automated Weather Observing System (AWOS) reported wind from 100° at 4 knots, 10 miles visibility, clear skies below 12,000 ft agl, temperature 21°C, dew point 17°C, and an altimeter setting of 30.05 inches of mercury (inHg). Remarks: automated station with a precipitation discriminator, lightning distant (defined as beyond 10 miles but less than 30 miles from the center of the airport) west, temperature 21.1°C, dew point 16.6°C. At 2115, the PVW AWOS reported calm wind, 10 miles visibility, clear skies below 12,000 ft agl, temperature 21°C, dew point 16°C, and an altimeter setting of 30.09 inHg. Remarks: automated station with a precipitation discriminator, lightning distant west and northwest, temperature 21.1°C, dew point 16.0°C. At 2135, the PVW AWOS reported wind from 300° at 26 knots with gusts to 36 knots, 10 miles visibility, light rain, scattered clouds at 4,500 ft agl, scattered clouds at 6,000 ft agl, a broken ceiling at 6,500 ft agl, temperature 16°C, dew point 11°C, and an altimeter setting of 30.17 inHg. Remarks: automated station with a precipitation discriminator, lightning distant southwest through northwest, temperature 15.5°C, dew point 11.0°C. The observations from PVW indicated visual flight rules ceilings at the surface at the time of the accident with no visibility restrictions. The sun set at 2051, and civil twilight ended at 2119, the approaching storm was visible as noted by a witness to the accident. PVW was the closest site with a National Weather Service (NWS) TAF. The TAF valid at the time of the accident, which was issued at 1820 and was valid for a 24-hour period beginning at 1900, indicated the following: Wind from 060° at 10 knots, greater than 6 miles visibility, scattered clouds at 5,000 ft agl, and a broken ceiling at 25,000 ft agl. Temporary conditions of variable wind at 25 knots with gusts to 45 knots, 2 miles visibility, thunderstorms and heavy rain, and a broken ceiling of cumulonimbus clouds at 3,000 ft agl were forecast between 2100 and 0100. Figure 2: KLBB WSR-88D reflectivity for the 0.5° elevation scan initiated at 2115 CDT with the lightning data. The closest NWS Weather Surveillance Radar-1988, Doppler (WSR-88D) was from Lubbock Preston Smith International Airport (LBB), Lubbock, Texas, which was located 31 miles south of the accident site at an elevation of 3,282 ft. Figure 2 shows the LBB WSR-88D base reflectivity images for the 0.5° elevation scans initiated at 2115. The image shows lightning flashes and strikes associated with a squall line, which are indicated by small black dots, north and west of the accident site between 2100 and 2115. The figure shows the gust front's location, depicted by a red line. The gust front was moving eastward over the accident site at the accident time. Figure 3: Severe thunderstorm warnings (red and green) and severe thunderstorm watch (blue) valid at the accident time. The first severe thunderstorm warning that included the accident site was issued at 2046 by the NWS Office in Lubbock, Texas. Another severe thunderstorm warning, which was valid for the accident site at the accident time, was issued at 2113; and a severe thunderstorm watch was issued at 1545 and was valid through 2300. Figure 3 shows the 2046 severe thunderstorm warning area outlined in red, the 2113 severe thunderstorm warning area outlined in green, and the severe thunderstorm watch area outlined in blue. The accident site is marked by the star in figure 3. The severe thunderstorm warnings reported 60 mph wind gusts and hail. FAA Advisory Circular AC 00-24C, "Thunderstorms," issued in February 2013, is a training guide for pilots on thunderstorm hazards. Figure 4 shows a cross-section of a squall line thunderstorm from AC 00-24B depicting a shelf cloud, gust front, and its related cold air outflow. A gust front