Benavides, TX, USA
N729MS
BEECH B100
The pilot obtained three weather briefings before departure. At that time, the current weather along the route of flight showed significant convective activity and a moving squall line, and the forecast predicted significant thunderstorm activity along the planned route of flight. The pilot was concerned about the weather and mentioned that he would be looking for "holes" in the weather to maneuver around via the use of his on-board weather radar. He decided to fly a route further south to avoid the severe weather. Radar data indicates that, after departure, the pilot flew a southerly course that was west of the severe weather before he asked air traffic control for a 150-degree heading that would direct him toward a "hole" in the weather. A controller, who said he also saw a "hole" in the weather, told the pilot to fly a 120-degree heading and proceed direct to a fix along his route of flight. The airplane flew into a line of very heavy to intense thunderstorms during cruise flight at 25,000 feet before the airplane began to lose altitude and reverse course. The airplane then entered a rapid descent, broke up in flight, and subsequently impacted terrain. Review of recorded precipitation data showed that there was substantial information available to the controller about moderate to extreme weather along the aircraft’s route of flight. While the controller stated that he saw a hole or clear area ahead of the aircraft, this is contradicted by both the recorded data and the statement of a second controller working the D-position at the time of the accident. The first controller did not advise the pilot of the severe weather that was along this new course heading and the pilot entered severe weather and began to lose altitude. The controller queried the pilot about his altitude loss and the pilot mentioned that they had gotten into some "pretty good turbulence." This was the last communication from the pilot before the airplane disappeared from radar. Review of recorded precipitation data showed that there was substantial information available to the controller about moderate to extreme weather along the aircraft’s route of flight. The controller did not provide advisories to the pilot regarding the adverse weather's immediate safety hazard to the accident flight as required by Federal Aviation Administration Order 7110.65. Examination of the recovered sections of flight control surfaces revealed that all of the fractures examined exhibited signs consistent with overstress failure. There was no evidence of preexisting cracking on any of the fracture surfaces examined and no preaccident anomalies were noted with the engines.
HISTORY OF FLIGHT On October 26, 2009, approximately 1143 central daylight time, a Beech B100 King Air, N729MS, registered to Mazak Properties, Incorporated, and operated by a private pilot, impacted terrain after encountering severe weather near Benavides, Texas. The personal flight was operated under the provisions of Title 14 Code of Federal Regulations Part 91 and an instrument flight rules (IFR) flight plan was filed. Instrument meteorological conditions prevailed. The private pilot and three passengers received fatal injuries and the airplane was destroyed. The flight departed Garner Field Airport (KUVA) Uvalde, Texas, and was destined for Leesburg International Airport (KLEE), Leesburg, Florida. Prior to departure, the pilot received three separate weather briefings from an Automated Flight Service Station (AFSS). A review of these communications revealed that the pilot was provided information regarding the severe weather conditions along his planned route of flight. The pilot expressed his concern about these conditions and altered his route of flight further south so he could maneuver around and through “holes” in the weather. A review of air traffic control (ATC) communications revealed that the accident airplane departed from Uvalde, Texas, about 1058. The pilot contacted Houston Air Route Traffic Control Center (ARTCC) sector 59 at 1105:08, and reported that he was at an altitude of 10,200 feet and climbing to 23,000 feet. He also continued to say, "All right if you don't mind helping us we're looking at the radar – it might be better for us to go down toward Laredo <unintelligible> route…looks like a squall line." The controller responded, "Niner mike sierra yes there is a very significant squall line between you and your destination. Not sure how you'll get through, but we'll work on it somehow." The pilot responded, "All right – I sure appreciate the help." At 1107:44, the pilot requested to proceed direct to Laredo. The controller responded, "…direct Laredo, direct Corpus, direct Leeville, rest of route unchanged." The pilot read back the route, and the controller cleared the accident airplane to climb to 25,000 feet, which was the pilot's requested final altitude. At 1122:23, the pilot stated that he had a request, and the controller acknowledged. The pilot continued, "uh, we're looking at a hole um going towards Corpus is it possible we could get about a one five zero degree heading try and work through that way <unintelligible>. The controller replied, "November niner mike sierra fly heading of one two zero when able proceed direct Corpus Christi rest of route unchanged." The pilot responded, "…sounds great one two zero and when able direct Corpus for mike sierra thank you." At 1140:43, the controller transmitted, "November niner mike sierra verify you're level flight level two five zero." The pilot replied, "No sir, we had dropped down to – we'd gotten into some pretty good turbulence we're at two four zero." The controller responded, "November niner mike sierra you've got to tell me these things…I've got a MOA below you at flight level two three zero and below so november niner mike sierra when able maintain flight level two five zero." The pilot transmitted, "Yes sir um I'm sorry sir.'" The controller then asked,"…and uh any injuries or uh damage?" The pilot did not reply and there were no further communications with him. At 1142:07, an expletive and propeller noise were heard on the same frequency used by the pilot, and for the next 35 seconds there was sound similar to that made by a stuck microphone conflicting with other transmissions. In response, the controller transmitted, "All right now everybody use caution – we had a stuck mic there for a while, that's very bad now." A review of recorded radar data revealed that after departing Uvalde, the airplane traveled on a southeasterly heading before it made a turn to the south at 1108. The airplane then traveled on this southerly heading for approximately 15 minutes before it turned back to a southeasterly heading toward Benavides, Texas. At 1140, when the airplane was approximately 6 ½ miles north of Benavides at an altitude of 25,000 feet, it entered a right turn toward the northwest and started to descend. The last radar return was received at 1141:46 at an altitude of 22,200 feet. The radar track went into "coast" status at 1142:55, indicating that the radar data processing system had lost track of the aircraft. A review of the National Weather Service (NWS) Corpus Christi, Texas, Weather Surveillance Radar-1988, Doppler (WSR-88D) weather and radar track data revealed that the airplane entered a line of echoes in the range of 40 to 54 dBZ (very heavy to intense) before it began to lose altitude and reverse course. The Federal Aviation Administration (FAA) defines reflectivity of 50 dBZ and greater as “extreme” intensity with severe turbulence, lightning, hail likely, and organized surface wind gusts. Stronger echoes with maximum reflectivies to 63 dBZ or “extreme” intensity were located in the immediate vicinity along the intended route of flight. PERSONNEL INFORMATION The pilot held a private pilot certificate for airplane single and multi-engine land, and instrument airplane. His last Federal Aviation Administration (FAA) second class medical was issued on January 10, 2008. At that time, he reported a total of 550 flight hours. The pilot’s logbook was never located. METEOROLOGICAL INFORMATION The closest weather reporting facility to the accident was from Jim Hogg County Airport (KHBV), Hebbronville, Texas, located approximately 24 miles southwest of the accident site at an elevation of 663 feet. The airport had an Automated Weather Observation System (AWOS-3) and reported the following conditions surrounding the time of the accident: At 1103, the weather was reported as wind from 210 degrees at 8 knots, visibility 7 miles, scattered clouds at 1,600 feet, ceilings broken at 2,200 feet, overcast at 7,000 feet, temperature 26 degrees Celsius, dew point 22 degrees Celsius, and a barometric pressure setting of 29.91 inches of Mercury. Remarks: automated observation system, lightning distant north, northeast, and southwest, temperature 25.9 degrees Celsius, dew point 21.5 degrees Celsius. At 1125, the weather was reported as wind from 310 degrees at 18 knots gusting to 26 knots, visibility 5 miles in moderate rain, scattered clouds at 1,000 feet, ceiling broken at 1,500 feet, overcast at 2,800 feet, temperature 20 degrees Celsius, dew point 18 degrees Celsius, and a barometric pressure setting of 29.95 inches of Mercury. Remarks: automated observation system, lightning distant northeast, hourly precipitation 0.19 inches, temperature 19.7 degrees Celsius, dew point 17.6 degrees Celsius. At 1143, the weather was reported as wind from 330 degrees at 21 knots gusting to 31 knots, visibility 4 miles in thunderstorms and heavy rain, scattered clouds at 800 feet, ceiling broken at 2,300 feet, overcast at 3,000 feet, temperature 18 degrees Celsius, dew point 17 degrees Celsius, and a barometric pressure setting of 29.94 inches of Mercury. Remarks: automated observation system, lightning distant north east and east, hourly precipitation 0.24 inches, temperature 17.7 degrees Celsius, dew point 16.5 degrees Celsius. At 1203, the weather was reported as wind from 350 degrees at 22 knots gusting to 32 knots, visibility 10 miles, scattered clouds at 800 feet, scattered at 2,300 feet, ceiling overcast at 3,000 feet, temperature 18 degrees Celsius, dew point 16 degrees Celsius, and a barometric pressure setting of 29.95 inches of Mercury. Remarks: automated observation system, lightning distant northeast through southeast,temperature 17.6 degrees Celsius, dew point 16.4 degrees Celsius. The NWS Corpus Chisti (KCRP) upper air sounding for 0700 indicated an unstable atmosphere with a Lifted Index of -6.8 and a K-Index of 31.6, which supported thunderstorm development across the region. The degree of instability and vertical wind profile also supported a moderate to strong risk of multicellular type thunderstorms in lines and clusters, with the potential for strong updrafts and downdrafts. The tropopause was identified at 54,000 feet. At the airplane's cruising altitude, the WSR-88D 2.4° elevation scan documented echoes of 40 to 49 dBZ along the flight track when the pilot lost altitude and reported encountering turbulence, and turned back into an area of 40 dBZ when the upset occurred. Echo tops of 18 dBZ or higher were detected between 30,000 to 34,000 feet over the accident site, with tops to 45,000 feet approximately 10 miles south-southeast of the accident site. The National Lightning Detection Network (NLDN) detected 140 cloud-to-ground lightning strikes between 1122 and 1202 within 15 miles of the accident site, and confirmed that active thunderstorms were occurring in the vicinity of the accident site. The NWS had Convective SIGMET 38C current over the area for an area of thunderstorms moving southeast at 20 knots, with tops to 37,000 feet. The advisory implied severe to extreme turbulence, severe icing, and low-level wind shear associated with the thunderstorms. The NWS also had AIRMET Zulu current for moderate icing conditions from the freezing level identified at 13,500 feet to 25,000 feet over the area. WRECKAGE AND IMPACT INFORMATION The National Transportation Safety Board’s on-scene investigation was conducted on October 27-29, 2009. A hand held global position receiver (GPS) was used to identify the position of the main wreckage as 27.6663 degrees north latitude, 98.4613 degrees west longitude. The main wreckage was located approximately 6 1/2-miles north of Benavides, Texas, on a remote cattle ranch. The associated debris was located in two general areas, situated about 0.8 nautical miles from each other. The overall wreckage distribution was consistent with an in-flight break-up. The main wreckage was located in a shallow impact crater that measured approximately 30-feet-wide. Damage to the dense overhead foliage surrounding the wreckage was limited, consistent with a near vertical descent path. The main wreckage was inverted and consisted of the cockpit, both engines, inboard sections of each wing, both propeller systems, the fuselage, all three landing gear, and the upper portion of the right outboard wing. The main wreckage was consumed by post-impact fire. The second area of wreckage was scattered in a centralized area south of where the main wreckage came to rest. It consisted of the outboard section of left wing, sections of the upper portion of the right wing, sections of the vertical stabilizer, both horizontal stabilizers, both elevators, and the rudder. The wreckage was recovered and moved to a secured facility where it was examined under the supervision of the Investigator-in-Charge on November 4-5, 2009. A Safety Board Structural Engineer, along with a representative of Hawker Beechcraft and Honeywell also participated in the examination/reconstruction. Examination of the recovered sections of the outboard section of wings, vertical stabilizer, rudder, horizontal stabilizer, and elevators revealed that all of the fractures examined exhibited signs consistent with overstress failure. There was no evidence of pre-existing cracking on any of the fracture surfaces examined. The left engine was still contained in the nacelle hardware and exhibited heavy impact damage to the upper portion of the nacelle. The nacelle sheet metal was formed around the upper portion of the engine and mount structure. The upper cowl sheet metal was removed to access the engine for detailed examination. The engine hardware aft of the gearbox accessory face was blackened with soot. The upper mount was bent down toward the top of the power section. The starter was in place on the aft side of the gearbox but the starter mount flange was fractured. The engine was not removed from the lower nacelle and mount hardware. The gearbox housing had impact damage to the left side of the top face and was cracked. The gearbox was also fractured in the inlet flow path area. The fuel pump housing was fractured in the fuel filter area and opened at the center split line between the low pressure and high pressure stages. The fuel control was impact damaged on top of the unit. The propeller pitch control and propeller governor were in place and their housings were intact. The fuel shutoff valve had impact damage and the lever arm was separated. Inspecting up the inlet of the engine, the leading edges of the impeller vanes appeared to be intact and undamaged. The power section rotating group was not free to rotate, as well as, the propeller and propeller shaft. The starter spline drive shaft was intact and was not sheared. The oil filter bypass indicator was not extended. The plenum exhibited impact damage on the top side of the part. The igniters were bent toward the bottom of the part and the plenum skin was torn around them. Several of the fuel manifold hoses were damaged by fire. The engine exhaust was not removed to inspect the turbine end of the engine. Several of the fuel manifold hoses were damaged by fire. Examination of the left propeller revealed that the forward housing was separated from the threads on the forward side of the hub. The three blades still attached to the hub were in a coarse blade angle position. The damage to all four blades is as follows: 1 blade was separated at the grip area. The separated blade was bent approximately 1 foot from the grip area. 1 blade had a slight bend approximately 1 foot from the tip. 1 blade was bent toward the front side of the blade. 1 blade was bent toward the aft side of the blade. The right engine was still contained in the nacelle hardware and there was heavy impact damage to the upper portion of the nacelle. The nacelle sheet metal was formed around the upper portion of the engine and mount structure. The upper cowl sheet metal was removed to access the engine for detailed examination. The engine hardware aft of the gearbox accessory face was blackened with what appeared to be soot. The amount of soot increased further aft on the top of the engine. The upper mount was separated at the forward end and was bent down against the top of the engine. The starter was separated at the mounting flange and was lying against the upper left portion of the power section. Several of the fuel manifold hoses were damaged by fire. The engine was not removed from the lower nacelle and mount hardware. The starter drive-spline shaft was intact and was not sheared, but was bent. The oil filter bypass indicator was not extended. The gearbox housing had impact damage to the left side of the top face and was cracked. The fuel pump and fuel control had been pushed down toward the engine and had pulled the fuel pump mounting studs from the back side of the gearbox housing. The gearbox to fuel pump drive shaft was intact and in place but was slightly bent down toward the power section of the engine. The fuel pump to fuel control flanges were broken, exposing the fuel control drive splines. The fuel control drive-spline shaft appeared to be intact. The prop pitch housing appeared to be intact and the mounting flange did not appear broken. The prop governor mounting flange was fractured. The fuel shutoff valve was impact damaged and fire damaged. Inspecting up the inlet of the engine, the leading edges of the impeller vanes appeared to be intact and undamaged. The power section rotating group was not free to rotate as well as the propeller and propeller shaft. The second stage compressor housing had wrinkles in the housing between the flanges. The engine plenum housing exhibited impact damage on most of the top side of the part. Several of the fuel manifold hoses were damaged by fire. Examination of the right propeller revealed that the spinner was impact damaged on one side and formed around one side of the propeller hub. One blade counterweight had an impact location through the spinner that indicates a coarse blade angle at the time of impact. Af
The pilot's failure to avoid severe weather, and the air traffic controller's failure to provide adverse weather avoidance assistance, as required by Federal Aviation Administration directives, both of which led to the airplane's encounter with a severe thunderstorm and the subsequent loss of control and inflight breakup of the airplane.
Source: NTSB Aviation Accident Database
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