Woody, CA, USA
N35SD
BEECH V35A
During a visual flight rules cross-country flight, air traffic control was providing flight-following services. The pilot informed the controller that there was cloud cover ahead and requested an instrument flight rules clearance and approach to the destination airport. The controller granted the clearance and then instructed the pilot to maintain 14,000 ft; the pilot read back the clearance. The pilot then requested a lower altitude and was advised to expect a lower altitude in 10 to 12 miles. The pilot was subsequently cleared for a descent to 7,000 ft and issued arrival instructions. Two minutes later, the controller advised the accident pilot of a pilot report of icing in the area. One minute later, the controller issued a clearance to 6,000 ft but received no response from the pilot. The controller issued the clearance again, and the pilot acknowledged the instruction. The controller relayed a nearby outside air temperature but received no response from the pilot. The controller made several attempts to contact the pilot and also asked another pilot to try to establish contact; all attempts were unsuccessful. Two minutes later, radar contact was lost. The wreckage was located about 1 mile from the last radar return and was distributed over the terrain for about 1/2 mile, indicating that an in-flight breakup had occurred. A postaccident examination of the airframe or engine revealed no anomalies that would have precluded normal operation. A weather study indicated that the airplane likely encountered light-to-moderate precipitation, especially near the end of the radar flight track. Precipitation and clouds would have reduced visibility. Considering the environmental freezing level, the airplane likely encountered supercooled liquid water and snowflakes about the time that voice communication was lost. Pilot reports in the immediate area described increasing instrument meteorological conditions (IMC) along with light-to-moderate icing conditions. The reports described the flight conditions as mostly smooth with some light turbulence when passing in and out of cloud tops. Along with the likely IMC, the airplane likely experienced moderate or greater icing conditions around the accident time. The airplane likely developed ice on the wings, which resulted in an aerodynamic stall followed by a loss of control and in-flight breakup during the descent.
HISTORY OF FLIGHTOn January 6, 2013, about 1606 Pacific standard time (PST), a Beech V35A, N35SD, experienced an in-flight break-up near Woody, California. The pilot/owner was operating the airplane under the provisions of 14 Code of Federal Regulations (CFR) Part 91. The private pilot and passenger sustained fatal injuries; the airplane was destroyed. The cross-country personal flight departed Imperial, California, about 1415, with a planned destination of Fresno, California. Visual meteorological (VMC) conditions prevailed, and no flight plan had been filed. The Federal Aviation Administration (FAA) reported that the pilot obtained flight following, and the airplane climbed to 16,500 feet. At 1549, the pilot informed Los Angeles Air Route Traffic Control Center (ARTCC) that there was cloud cover ahead, and requested an instrument flight rules (IFR) clearance into Fresno. The clearance to Fresno via direct TULE ALTTA8 Arrival was granted at 1550. The controller instructed the pilot to maintain 14,000 feet, and the pilot read back the clearance. At 1552 and 1558, the pilot requested a lower altitude, and was advised to expect a lower altitude in 10-12 miles. On the 1558 transmission, the pilot stated they were waiting for some buildup, but hadn't gotten any yet (he did not specify what kind of buildup). The pilot contacted Bakersfield Approach Control as instructed at 1600, and requested a lower altitude. The approach controller cleared the pilot for a descent to 7,000 feet, and issued the TULE ALTTA8 Arrival. Two minutes later, the controller advised the accident pilot of a pilot report of icing in the area. At 1603, the controller issued a clearance to 6,000 feet, but received no response from the pilot. At 1604, the controller issued the clearance again, and the pilot acknowledged the instruction. The controller followed with a nearby outside air temperature of -6 degrees centigrade, but received no response from the pilot. The controller made several attempts to contact the pilot, and also asked another pilot to try to establish contact; all attempts were unsuccessful. At 1606, radar contact was lost 9 miles south of the Tule very high frequency omni-directional radio range (VOR). The FAA issued an alert notice (ALNOT) at 1734. The wreckage was subsequently located about 1 mile from the last radar return. PERSONNEL INFORMATIONA review of Federal Aviation Administration (FAA) airman records revealed that the 72-year-old pilot held a private pilot certificate with ratings for airplane single-engine land, multiengine land, and instrument airplane. The pilot's most recent medical certificate on file with the FAA Airman and Medical Records Center located in Oklahoma City, Oklahoma, was a third-class certificate issued on April 27, 2009. It had the limitation that the pilot must wear corrective lenses. The pilot reported a total time of 7,000 hours with 0 hours in the previous 6 months. One logbook was found for the pilot that contained two pages of entries in 2012 for 14 flights; all of the flights were in the accident airplane. No totals were entered in the data blocks, but the hours recorded indicated an estimated 23 hours of flight time with one IFR approach flown into Fresno. AIRCRAFT INFORMATIONThe airplane was a Beech V35A, serial number D-8812. A review of the airplane's logbooks revealed that it had a total airframe/tachometer time of 6,646.92 hours at the last annual inspection dated September 20, 2012. The airplane was not certified for flight in known icing conditions, and had no de-icing or anti-ice provisions installed other than pitot heat. The engine was a Continental Motors, Inc. (CMI), IO-550-B12B, serial number 685906. It was installed as a new engine on August 20, 2001, at a tachometer time of 4,879.6 hours. An entry in the engine logbook on March 13, 2012, indicated an engine total time of 1,500.23 hours at an airframe total time of 6,475.93 hours. METEOROLOGICAL INFORMATIONThe National Transportation Safety Board's (NTSB) Meteorologist was not on scene for this investigation and gathered all the weather data for this investigation from the NTSB's Washington D.C. office and from official National Oceanic and Atmospheric Administration (NOAA) National Weather Service (NWS) sources including the National Climatic Data Center (NCDC). The meteorologist prepared a Weather Study report, which is in the public docket for this accident. Pertinent parts of the report follow. The NWS Surface Analysis Chart for 1600 PST indicated that the accident site was located in a region where clouds and precipitation would be expected. The NWS Storm Prediction Center (SPC) Constant Pressure Charts for 1600 PST indicated that the accident site was located in a very favorable location for vertical motion, clouds, and precipitation given the low, mid, and upper-level environment. No thunderstorm products or convective outlooks were valid for the accident site at the accident time. Surface observations for the area surrounding the accident site was documented utilizing official NWS Meteorological Aerodrome Reports (METARs) and Specials (SPECIs). Meadows Field Airport (KBFL) was the closest official weather station to the accident site; it was located 3 miles northwest of Bakersfield, California, and had an Automated Surface Observing System (ASOS) whose reports were supplemented by the air traffic control (ATC) tower. KBFL was located 18 miles south-southwest of the accident site, at an elevation of 510 feet, and had a 14 degree easterly magnetic variation. KBFL weather at 1554 PST was wind from 330 degrees at 6 knots, 10 miles visibility and light rain, an overcast ceiling at 3,600 feet agl, temperature of 10 degrees C, dew point temperature of 6 degrees C, and an altimeter setting of 30.08 inches of mercury. The remarks section noted that it was an automated station with precipitation discriminator, and rain began at 1538 PST. Porterville Municipal Airport (KPTV) was located 3 miles southwest of Porterville, California, and had an Automated Weather Observing System (AWOS) whose reports were not supplemented by an official observer. KPTV was located 21 miles north-northwest of the accident site, at an elevation of 443 feet, and had a 15-degree easterly magnetic variation. KPTV weather at 1535 PST was wind calm, 10 miles visibility, a broken ceiling at 4,800 feet agl, overcast skies at 9,500 feet agl, temperature of 9 degrees C, dew point temperature of 6 degrees C, and an altimeter setting of 30.10 inches of mercury. The remarks section noted that it was automated station without a precipitation discriminator. Upper Air Data from a North American Mesoscale Model (NAM) upper air sounding was generated for the accident site. The 1600 PST sounding was plotted on a standard Skew-T log P diagram with the derived stability parameters, and this data was analyzed utilizing the Rawinsonde Observation program (RAOB) software package. The sounding depicted a conditionally unstable vertical environment with the Lifted Condensation Level (LCL) at 2,897 feet msl, a Convective Condensation Level (CCL) of 4,066 feet, and a Level of Free Convection (LFC) at 3,625 feet. The freezing level was identified at 4,603 feet. The precipitable water value was 0.49 inches. The 1600 PST model sounding indicated a relatively moist conditionally unstable vertical environment, and this vertical environment would have been supportive of clouds and rain showers with the other lifting mechanisms in the area of the accident. While this environment had very little Convective Available Potential Energy (CAPE) the LCL and CCL were quite low so that any clouds or rain showers that developed would reduce visibility, but not grow that much vertically. Icing conditions were indicated by RAOB from 5,000 to 7,000 feet msl. RAOB identified clouds from the surface through 10,000 feet msl, then another layer of clouds between 14,000 feet and 21,000 feet msl. The sounding wind profile indicated there was a surface wind from 321 degrees at 3 knots, and the wind backed around to the north through 30,000 feet msl with the strongest winds around 55 knots at 27,000 feet msl. No low-level wind shear (LLWS) was indicated by RAOB. Two layers of possible clear-air turbulence were indicated from 12,000 to 16,000 feet msl and 19,000 feet through 30,000 feet msl. Visible and infrared data from the Geostationary Operational Environmental Satellite number 15 (GOES-15) data was obtained from the NCDC and processed with the NTSB's Man-computer Interactive Data Access System (McIDAS) workstation. The visible imagery indicated a large amount of cloud cover at and around the accident site at the accident time with the tops of the clouds to the north and west having a cumuliform-like top appearance. This would likely correspond to the showers moving from north to south across the accident site. Based on the brightness temperatures above the accident site and the vertical temperature profile provided by the 1600 PST model sounding, the approximate cloud-top heights over the accident site were around 13,000 feet at both 1600 and 1630 PST. The closest NWS Weather Surveillance Radar-1988, Doppler (WSR-88D) was KHNX located near Hanford, California, approximately 51 miles northwest of the accident site at an elevation of 243 feet. Level II archive radar data was obtained from the NCDC utilizing the NEXRAD Data Inventory Search and displayed using the NOAA's Weather and Climate Toolkit software. A radar summary image from 1615 PST had reflectivity values that indicated very light to moderate echoes near the accident site around the accident time. The meteorologist reported that the airplane likely encountered light to moderate precipitation, especially near the end of the ATC flight track. It also likely encountered a shower that was over 10,000 feet in depth; the shower activity was moving south-southeastward with time. There were no lightning strikes near the accident site around the time of the accident. A 3-dimensional view of the KHNX WSR-88D base reflectivity for the elevation scan was plotted on the Google Earth image for a time comparison with the base reflectivity images. The meteorologist reported that the image showed that the accident airplane likely encountered light to moderate precipitation while flying generally northwestward. In addition, the precipitation and clouds would have reduced visibility. The closest NWS WSR-88D with Dual-Polarization (dual-pol) technology was KHNX. Given the base reflectivity and dual-pol values, along with the environmental freezing level, the accident airplane likely encountered ice crystals of different shapes and sizes, with a few snowflakes or supercooled liquid water droplets mixed in as well. However, the majority of the meteorological targets would have likely been ice crystals. The accident airplane likely encountered supercooled liquid water and snowflakes around 1604 PST. There was likely a mix between the supercooled liquid water and snowflakes. Along with the likely IMC conditions the pilot was flying in due to the cloud cover and precipitation, the accident airplane likely experienced moderate or greater icing conditions around the accident time. AIRMETs Sierra, Tango, and Zulu were valid for the accident airplane's flight level at the accident time. They were issued at 1245 PST (with AIRMET Zulu updated again at 1550 PST), and forecasted moderate icing conditions, moderate turbulence, and mountain obscuration by clouds, precipitation, and mist. There was no record of the accident pilot receiving a weather briefing or looking at weather information before the flight. It was confirmed that the accident pilot did not receive a weather briefing from official sources. Another pilot flew through the Bakersfield area in a Cessna 421C on an IFR flight plan before the accident time frame, and the complete statement is provide as attachment 1 to the factual report. The pilot described increasing IMC conditions as he flew in and out of cloud tops in and north of the Bakersfield area. Also, the pilot experienced light to moderate icing conditions for which the deice boots were activated. The pilot had to increase the frequency of the deicing boots the further north he traveled while the IMC conditions worsened with solid cloud cover. As the pilot descended into the Porterville area, the IMC conditions continued until 1,500 feet agl, but the temperatures climbed above freezing around 3,500 to 4,000 feet agl. The pilot described the flight as "mostly smooth" with some light turbulence when passing in and out of cloud tops. These statements matched the pilot reports (PIREPs) from around the accident area, which are described in Section 7.0 of the meteorologist's factual report. AIRPORT INFORMATIONThe airplane was a Beech V35A, serial number D-8812. A review of the airplane's logbooks revealed that it had a total airframe/tachometer time of 6,646.92 hours at the last annual inspection dated September 20, 2012. The airplane was not certified for flight in known icing conditions, and had no de-icing or anti-ice provisions installed other than pitot heat. The engine was a Continental Motors, Inc. (CMI), IO-550-B12B, serial number 685906. It was installed as a new engine on August 20, 2001, at a tachometer time of 4,879.6 hours. An entry in the engine logbook on March 13, 2012, indicated an engine total time of 1,500.23 hours at an airframe total time of 6,475.93 hours. WRECKAGE AND IMPACT INFORMATIONThe NTSB IIC examined the wreckage on site on January 8, 2013. The debris path was over ½ mile long. The first pieces were from the right ruddervator. Both wings separated, and were in the middle of the debris field. The cabin separated into several sections that were scattered throughout the center of the debris field. The inverted engine was the last major piece of debris; the engine exhibited significant damage to both top and bottom sides. The propeller remained attached to the engine. Two blades were complete, but the third blade fractured and separated about 6 inches from the hub; the fracture surface was jagged and irregular. COMMUNICATIONSThe pilot was in contact with Bakersfield Approach Control on frequency 118.9. MEDICAL AND PATHOLOGICAL INFORMATIONThe Kern County Sheriff/Coroner completed an autopsy, and determined that the cause of death was multiple blunt force trauma. The FAA Forensic Toxicology Research Team, Oklahoma City, Oklahoma, performed toxicological testing of specimens of the pilot. They did not perform tests for carbon monoxide or cyanide. The report contained the following findings for tested drugs: Losartan detected in muscle and liver; Metropolol detected in detected in muscle and liver. The report contained the following findings for volatile: 10 (mg/dL, mg/hg) ethanol detected in muscle; no ethanol detected in the brain. The report stated that the ethanol found in this case was from sources other than ingestion. TESTS AND RESEARCHThe NTSB IIC, the FAA, Beech, and CMI examined the wreckage at Aircraft Recovery Service, Littlerock, California, on March 15, 2013. A full report is contained within the public docket for this accident. Airframe There were multiple disconnects in the flight control system. All identified flight control cables were splayed. All fractured and separated components had angular and jagged fracture surfaces. The left wing sustained more damage than the right wing. It fragmented into two pieces, and both pieces exhibited spanwise creases. The wing separated midspan along a jagged fracture surface. The spar at the separation point remained permanently deformed about 30 degrees in an upward direction. The aileron separated into three sections. The inboard aileron tore along a jagged angular plane at the inboard hinge; the rod end separated at the hinge. The inboard portion of the aileron's middle section also remained permanently deformed in an upward direction. The outboard hinge, and the aileron section outboard of it, remained attached to the wing. The flap remained attached to the inboard half of the left wing. The right wing separated at the wing root. There were chevron wrinkles from the front leading edge at the tip aft to the trailing edge. The chevrons
An in-flight encounter with icing conditions during descent, which resulted in the airplane exceeding its critical angle-of-attack and experiencing an aerodynamic stall followed by an in-flight breakup.
Source: NTSB Aviation Accident Database
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