Silverton, CO, USA
N25153
SOCATA TB21
The non-instrument-rated pilot departed for his destination with active weather advisories for his route of flight for instrument flight rules (IFR) conditions and mountain obscuration due to clouds, precipitation, and mist. After departure, the pilot attempted to remain in visual flight rules (VFR) flight by climbing above 18,000 feet mean sea level and proceeding toward his destination. When queried by an air traffic controller, the pilot stated that he could not descend due to weather. In addition, he stated that he was not instrument rated or qualified. No further transmissions were made by the pilot. Witnesses near the accident site reported low clouds with light snow flurries. On-site wreckage distribution was consistent with an in-flight breakup. Further, an examination of the wreckage revealed signatures on the airplane’s right wing consistent with it failing in overload in the upward direction and signatures on the empennage and tail section consistent with their failure in overload in the downward direction, indicating the failures were due to loads that exceeded the airplane’s structural limits. A weather study revealed the potential for clouds at the pilot’s cruising altitude, which increased the potential for VFR flight into instrument meteorological conditions (IMC). Therefore, it is likely that the pilot encountered IMC, became spatially disoriented, and then maneuvered the airplane in a manner that exceeded the airplane’s structural limits while trying to return to level flight and avoid mountainous terrain.
HISTORY OF FLIGHT On December 3, 2011, about 1335 mountain standard time (MST), a Socata TB21 airplane, N25153, collided with terrain near Silverton, Colorado. The non-instrument rated private pilot and three passengers were fatally injured. The airplane was registered to and operated by a private individual under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. Instrument meteorological conditions (IMC) prevailed and a flight plan had not been filed for the cross-country flight. The flight had departed the Animas Air Park Airport (00C), Durango, Colorado, at 1319 and was en route to the Aspen-Pitkin County Airport (ASE), Aspen, Colorado. A review of air traffic control (ATC) recordings revealed that the pilot contacted ATC while at flight level 200 (about 20,000 feet) and 12 miles southeast of Telluride, Colorado. The pilot requested visual flight rules (VFR) flight following to ASE, and reported that he could not descend below his altitude and maintain VFR. Moments later, the airplane disappeared from radar and contact with the pilot was lost. There were no reported distress calls from the pilot. There were numerous people in and near the town of Silverton who reported hearing the airplane; however, there were no reports of anyone seeing the airplane before impact. The witnesses described the weather as snowing with poor visibility. One witness reported that while cross-country skiing, he heard the airplane very clearly directly above him. The witness said it sounded like the airplane was doing aerobatics or tricks, and that it sounded like the pilot was having a hard time figuring out where he was going. Another witness, located about a mile from the crash site, reported hearing the airplane overhead. She stated that the airplane sounded like it was racing down through the sky, and then back up very fast, then back down again. The engine volume varied as if the airplane was changing elevation very fast. She thought someone was “up there fooling around.” The National Transportation Safety Board (NTSB) investigator-in-charge (IIC) asked her if she had ever heard an airplane performing aerobatics before. She responded, “Yes, on TV, and that is what it sounded like.” PERSONNEL INFORMATION The pilot, age 59, held a private pilot certificate for airplane single engine land. He was issued a third class medical on October 4, 2011, with the restriction to have glasses for near vision. A review of the pilot’s log book revealed that the pilot had accrued 593.5 hours total time, with 217.4 hours in the accident airplane. The pilot was not instrument rated and had only logged 4.4 hours of simulated instrument time, the last of which was recorded on August 21, 2001. The pilot’s log book did not record any recent instrument flight training. The pilot’s last flight review was flown on July 11, 2011, in the accident airplane. AIRCRAFT INFORMATION The accident airplane was a Socata TB21, was a low wing, four-place airplane, with retractable gear. The airplane was powered by a 250-horsepower, turbo-charged, fuel injected, Lycoming TIO-540-AB1AD engine driving a three-bladed, metal, constant speed Hartzell HC-C3YR-1RF propeller installed per a supplemental type certificate. The airplane’s maintenance records were not recovered during the course of the investigation and the date of the airplane’s last annual inspection is not known. Utilizing a comment in the pilot’s logbook referencing the airplane’s tachometer time, and adding the pilot’s subsequent flight time, the airplane had at least 2,120 hours prior to the accident flight. METEOROLOGICAL INFORMATION A weather study was conducted by an NTSB meteorologist. The study revealed that a surface trough and low pressure system existed near the accident site, which would produce clouds and precipitation. Converging surface winds in the area also produced a lifting mechanism for the existing clouds. In addition, a mid-level trough moved east through the airplane’s flightpath. This mid-level trough would also be expected to produce clouds and precipitation in the mountain terrain of Colorado. Visible and infrared data obtained via a Geostationary Operational Environmental Satellite (GOES) for the accident site indicated a cloud tops increased from 13,000 feet msl at 1200 MST to a height of between 19,000 and 22,000 feet msl at 1400 MST. Review of echoes from National Weather Service Weather Surveillance Radar located in Grand Junction, Colorado, recorded light precipitation echoes near the accident site. Airmen’s Metrological Information (AIRMET) issued prior to the airplane’s departure and valid through the planned flight time and route of flight advised of the potential for the following conditions: moderate turbulence, moderate icing, instrument flight rules (IFR) conditions with precipitation and mist, and mountain obscuration due to clouds, precipitation, and mist. Witnesses that had heard the airplane reported that the weather near the accident site consisted of low clouds, with light snow. At 1335, an automated weather observation station located at the Telluride Regional Airport (KTEX), Telluride, Colorado, located about 13 miles northwest of the accident site reported wind from 230 degrees at 4 knots, visibility 10 statute miles, scattered clouds at 1,900 feet, a broken cloud layer at 3,700 feet, an overcast ceiling at 6,000 feet, temperature 27 Fahrenheit (F), dew point 21 F, and a barometric pressure of 29.82 inches of mercury. COMMUNICATIONS The pilot was in radio contact with Denver Center. The pilot requested flight following to Aspen, and reported about 12 nautical miles southeast of Telluride. Denver Center confirmed with the pilot that he was flying via visual flight rules (VFR) at “20,000 [feet].” Denver Center reminded the pilot that in order to fly VFR that he needed to be below the flight levels (the flight levels normally start at 18,000 feet msl). The pilot reported that he would descend below the flight levels as soon as he could. Denver Center asked the pilot if he could maintain VFR below his current altitude, which the pilot responded that he could not. Denver Center then asked the pilot if he was capable of IFR flight, which the pilot responded “I’m capable. I’m studying it at this time, but if you could help me head on over, I’d sure appreciate it.” Denver Center asked the pilot if he’s capable and qualified for IFR flight. The pilot replied that he was not qualified. That was the last radio communication from the pilot. WRECKAGE AND IMPACT INFORMATION The airplane wreckage came to rest in snow covered mountainous terrain containing tall pine trees. The debris field began with the airplane’s right wing, and continued down the mountain’s slope about 1,200 feet along a magnetic heading of 065 degrees. The debris field’s elevation varied between 10,400 feet msl and 9,750 msl. The distribution of wreckage, and damage to the trees was consistent with an inflight breakup. Terrain, snow, and weather prevented a thorough examination of the wreckage on-scene and a follow up investigation was conducted once the wreckage was recovered from the mountains. An examination of the airplane was conducted by the NTSB investigator-in-charge (IIC) and a technical advisor from the airframe manufacturer. The examination discovered that the flight controls were fractured in multiple locations; however when reconstructed, the controls appeared to be continuous prior to the accident, and all fractures displayed signatures of overload. The left wing was bent upwards from the wing root to near 1/3 span before bending downwards. 45-degree creasing was noted near the left wing’s root. The right wing was fractured and separated immediately outboard from the wing spar’s doubler. The top of wing spar’s “I-beam” structure had been twisted forward and compressed downwards. The right wing displayed sign of upwards bending; the right flap was bent upwards near its mid-span. When reconstructed, the right wing had been displaced upwards over 80 degrees from its normal position. The airplane’s empennage displayed creasing near the aft section of the cabin and near the middle of the empennage. Airplane skin and pop-rivets displayed signatures of tearing and buckling in the downwards direction. Cockpit instrumentation was examined. The turn indicator depicted the airplane in the inverted position. The altimeter Kollsman windows displayed 29.92. The attitude indicator displayed an inverted attitude of approximately 190 degrees right roll with a nose down attitude of about 45 degrees. The attitude indicator’s gyro displayed rotational scoring. In addition, the vacuum pump was disassembled and displayed signatures of rotation scoring. The airplane’s propeller blades were examined and labeled A, B, and C for reporting purposes only. Blades A and B were heavily damaged when compared to the relatively undamaged blade C. Blade A remained displayed S-bending towards to non-cambered side, leading edge polishing, gouges in the leading edge, and chord-wise scratches. Blade B had fractured from the propeller hub and displayed signatures of leading edge polishing, gouges in the leading edge, and chord-wise scratches. Blade C was relatively undamaged. The engine was examined by the NTSB’s IIC and a technical advisor from the engine manufacturer. Damage to the engine, including the rocker arms, precluded a compression check. However, when the propeller was rotated by hand, continuity was established from the crankshaft through to the hydraulic lifts. In addition, the cylinders’ rocker arms operated normally. No anomalies were detected with the engine. MEDICAL AND PATHOLOGICAL INFORMATION An autopsy was performed on the pilot by the Colorado District 21 medical examiner as authorized by the San Juan County Coroner. The cause of death was blunt trauma. The manner of death was ruled an accident. Forensic toxicology was performed on specimens from the pilot and a passenger by the FAA Bioaeronautical Sciences Research Laboratory, Oklahoma City, Oklahoma. The pilot’s specimens were not suitable to test for carbon monoxide and cyanide. Forensic testing on the pilot’s specimens did not detect the presence of ethanol or drugs. Forensic testing of specimens from a passenger did not detect the presence of carbon monoxide or cyanide. ADDITIONAL INFORMATION Excerpt from the FAA’s Airplane Flying Handbook, 8083-3 In reference to Inadvertent VFR flight into IMC, section 16 of the handbook states the following: “Accident statistics show that the pilot who has not been trained in attitude instrument flying, or one whose instrument skills have eroded, will lose control of the airplane in about 10 minutes once forced to rely solely on instrument reference.” “If the natural horizon were to suddenly disappear, the untrained instrument pilot would be subject to vertigo, spatial disorientation, and inevitable control loss.” Previous NTSB recommendation In 2005, the NTSB proposed recommendation A-05-025 to the FAA which recommended: For pilots holding a private, commercial, or airline transport pilot certificate in the airplane category who do not receive recurrent instrument training, add a specific requirement that the biennial flight review include a demonstration of control and maneuvering of an airplane solely by reference to instruments, including straight and level flight, constant airspeed climbs and descents, turns to a heading, and recovery from unusual flight attitudes. The recommendation’s status is listed as “open-unacceptable response.”
The non-instrument-rated pilot’s decision to embark on a flight through forecasted instrument meteorological conditions (IMC), and his subsequent flight into IMC, which resulted in the pilot’s spatial disorientation and subsequent maneuvering of the airplane in a manner that exceeded the airplane’s structural limits.
Source: NTSB Aviation Accident Database
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