Aviation Accident Summaries

Aviation Accident Summary CEN09FA135

Wray, CO, USA

Aircraft #1

N840NK

Gulfstream Aerospace Corp Commander

Analysis

The airplane was "cleared for the approach" and approximately eight minutes later was observed emerging from the clouds, flying from west to east. Witnesses reported that the nose of the airplane dropped and the airplane subsequently impacted terrain in a near vertical attitude. Impact forces and a post impact fire destroyed the airplane. Examination of the airplane's systems revealed no anomalies. Weather at the time of the accident was depicted as overcast with three to six miles visibility. An icing probability chart depicted the probability for icing during the airplane's descent as 76 percent. AIRMETS for moderate icing and instrument meteorological conditions had been issued for the airplane’s route of flight. Another airplane in the vicinity reported light to moderate mixed icing. It could not be confirmed what information the pilot had obtained in a weather briefing, as a briefing was not obtained through a recorded source. A weight and balance calculation revealed that the accident airplane was 1,000 pounds over gross weight at the time of departure and 560 pounds over gross weight at the time of the accident. It was estimated that the center of gravity was at or just forward of design limitations.

Factual Information

HISTORY OF FLIGHT On January 15, 2009, approximately 0700 mountain standard time, a Gulfstream Aerospace Corporation Commander Division 690 C, N840NK, owned by A David Miller Trustee, and operated by J-W Operating Company was destroyed when it impacted terrain four miles north, northeast of Wray Municipal Airport (K2V5), Wray, Colorado. A post impact fire ensued. Instrument meteorological conditions prevailed at the time of the accident. The flight was being conducted under the provisions of Title 14 Code of Federal Regulation Part 91 on an instrument flight rules (IFR) flight plan. The airline transport certificated pilot, commercial certificated second pilot, and commercial certificated passenger were fatally injured. The cross-country flight departed Centennial Airport (KAPA), Denver, Colorado, approximately 0630 and was en route to K2V5. According to J-W Operating Company, the airline transport certificated pilot, an occasional contract pilot for J-W Operating Company, was on board the airplane for positioning purposes; after the flight from KAPA to K2V5 to Addison Airport, Dallas, Texas, (KADS), he intended to ferry another company airplane back to KAPA later that day. The accident airplane was based in KAPA and the flight was scheduled to pick up one additional passenger in Wray before continuing on to KADS. According to records provided by the Federal Aviation Administration (FAA), N840NK was in radio communications with Denver Air Route Traffic Control Center (ZDV) prior to the accident. Approximately 0634 the controller queried N840NK about which heading would take him direct to Wray. N840NK responded that a heading of 065 degrees would take them direct to ETUDE, the initial approach fix for the Global Positioning System (GPS) approach to Runway 17. The controller then cleared N840NK to fly direct to ETUDE. At 0646:06 the controller cleared the flight to "descend at pilot's discretion maintain six thousand." N840NK acknowledged this transmission. At 0646:28 the controller provided the special automated surface observation report for Akron, Colorado (52 miles west of K2V5). This weather included a visibility of four miles, mist, overcast at one hundred feet, and a temperature and dew point of minus twelve. At 0647:02 the controller provided the special weather report for Imperial, Kansas (42 miles northeast of K2V5). This weather included a visibility of three miles, light snow, and overcast at 1,600 feet. N840NK acknowledged the relay of both weather reports. At 0652:44 the controller cleared N840NK to "cross initial [approach fix] at or above six thousand, cleared [for the] approach to the Wray airport." Radar data, provided by ZDV in National Track Analysis Program (NTAP) format, depicted the accident flight from the time of departure from KAPA. The airplane initially climbed to 11,000 feet mean sea level (msl). At 0647:43 the airplane initiated a descent. The last radar information was recorded at 0649:14, at an altitude of 9,900 feet, 32 miles west of K2V5. Multiple witnesses reported seeing the accident airplane flying from the southwest to the northeast. The airplane was low to the ground and flew across highway 385. Shortly thereafter, the airplane pitched down to a near vertical attitude and began to rotate. The airplane impacted the ground nose first and a fire erupted. The Yuma County Sheriff’s Department took witness statements from nine individuals; six of whom observed the accident airplane prior to impact. The National Transportation Safety Board (Safety Board) Investigator in Charge (IIC) interviewed three witnesses. These witnesses were located west of the impact location. Several of the witnesses heard the accident airplane just to the northwest of their location. The airplane was not seen until it emerged from the clouds. The witnesses observed the airplane "flying low" and several stated that the "nose dropped" or that the airplane descended "nose first" towards the ground. PERSONNEL INFORMATION The pilot (seated in the left seat), age 33, held an airline transport pilot certificate with airplane single engine land, and multiengine land ratings last issued on September 26, 2008. He was issued a first class airman medical certificate on March 31, 2008. The certificate contained no limitations. The pilot’s flight logbook was not located. According to his last application for airman certification, dated September 26, 2008, he reported a total time of 2,454 hours; 220 of which was logged in instrument conditions. According to his employer (International Jet Aviation Services), he had logged approximately 2,728 hours. The second pilot (seated in the right seat), age 53, held a commercial pilot certificate with airplane single engine land, multiengine land, and instrument ratings last issued on December 3, 1996. He was issued a second class airman medical certificate on March 11, 2008. The certificate contained the limitation pilot "must wear lenses for near vision while flying." According to the second pilot’s logbook, he had logged no less than 10,211.3 hours total time; 1,149 hours were logged in multiengine “turbo propeller” aircraft, 615.9 hours in actual instrument conditions, and 91.4 hours in simulated instrument conditions. J-W Operating estimated that he had flown 9 hours during the week preceding the accident. According to J-W Operating Company, the commercial pilot lived in Wray and was very familiar with the airport, approaches, and geography. AIRCRAFT INFORMATION The accident airplane, a Gulfstream Aerospace Corporation Commander Division 690 C (serial number 11734) was manufactured in 1984, and subsequently refurbished earning the trade name of Grand Renaissance Commander. It was registered with the Federal Aviation Administration on a standard airworthiness certificate for normal operations. Two Allied Signal (Garrett) TPE-331-10T-513K turbine engines (as indicated by the engine data plates) limited at 717.5 horsepower at 1,591 rpm powered the airplane. The engines were equipped with three-bladed Dowty Rotol propellers. The airplane was registered to A David Miller Trustee, operated by J-W Operating Company, and was maintained under a periodic inspection program in accordance with the Twin Commander maintenance manual. A review of the maintenance records indicated that a 150 hour periodic inspection was completed on November 7, 2008, at an airframe total time of 7,189.9 hours. The airplane had flown approximately 25 hours between the last inspection and the accident and had an estimated total airframe time of 7,215 total hours. METEOROLOGICAL INFORMATION Aviation area forecasts were issued for Colorado by the Aviation Weather Center in Kansas City, Missouri, at 0445 the day of the accident. The forecast for the northern plains at the time of the accident predicted overcast sky conditions at 6,000 feet with cloud tops at 8,000 feet, and visibility 3 to 5 statute miles in mist. Airman's Meteorological Information (AIRMET) Zulu for icing and freezing levels was issued the day of the accident at 0145. Moderate ice between the freezing level and 14,000 feet was forecast. The freezing level was anticipated between the surface and 6,000 feet msl. AIRMET Sierra for IFR was issued at 0145. Ceilings below 1,000 feet and visibility below 3 miles in precipitation and mist was forecast. The accident airplane's route of flight was included in both AIRMET Zulu and Sierra. The closest official aviation weather observation station was Imperial Municipal Airport (KIML) Imperial, Nebraska, located 38 nautical miles (nm) northeast of the accident site. The elevation of the weather observation station was 3,275 feet msl. The routine aviation weather report (METAR) for KIML, issued at 0653, reported, winds, 140 degrees at seven knots, visibility, six miles in haze; sky condition, overcast 1,600 feet; temperature minus 12 degrees Celsius (C); dew point, minus 14 degrees C; altimeter, 30.49 inches. A Nebraska Department of Roads weather observation station, located in Haigler, Nebraska, (13.5 miles east of Wray, Colorado) recorded weather at 0655 as temperature 12.4 degrees Fahrenheit (F), dew point 9.8 degrees F, and winds east-southeast at 4 miles per hour with gusts to 6 miles per hour. Level II Doppler weather radar for Goodland, Kansas, scanned the accident area at 0647:10, 0656:55, and 0606:41. No weather radar echoes were recorded in the accident area around the time of the accident. Geostationary Operation Environment Satellite 11 recorded infrared images at 0645:13 and 0700:14. The brightness values recorded over Wray were 154 and 157 respectively. These brightness values correspond to radiative temperatures of minus 20 degrees and minus 21 degrees C. These values and temperatures correspond to cloud tops of 16,000 and 17,000 feet msl respectively. An icing probability image was generated for the accident route of flight using McIDAS-V. The icing probability near Wray, Colorado, ranged from 30 to 76 percent, depending on altitude. Vertical icing probability over Wray increased from zero probability at the surface to 60 percent at an altitude of 4,900 feet msl and 76 percent at an altitude of 5,900 feet msl. The probability then decreased to 30 percent at an altitude of 8,200 feet msl, and towards zero as the altitude increased. Neither pilot had obtained a weather briefing through the FAA Flight Service Station or by utilizing a Direct User Access Terminal System (DUATS). According to fellow employees, the second pilot commonly utilized “Flightplan.com” to file flight plans and obtain weather information. In a written statement received by a King Air pilot, he departed KAPA at 0711 en route to Burlington, Colorado (KITR), (52 miles south of K2V5) and cruised at 17,000 feet. He stated that initially the cloud tops were just below 17,000 feet and then "gradually rose slightly above 17,000." He stated that they "started picking up ice and the de-ice boots did not cleanly shed the ice." During the descent they were "in clear air between layers from… 15,000 feet down to about 12,000 feet." Clouds were continuous from 12,000 feet to "about 600 feet above ground level" (agl). He stated that they encountered "at least light icing throughout the descent and approach and frequently cycled the boots." The King Air pilot departed KITR at 0748 en route to Scott City, Kansas (KTQK), (129 miles southeast of K2V5) and cruised at 11,000 feet. He stated that they continued to encounter at least light icing conditions and broke out of the clouds at 1,500 feet agl. He stated that after landing he noted a "significant accumulation of ice on the airplane." The King Air pilot provided photographs of the icing accumulated on the flight to KTQK. The photographs depicted mixed icing varying in thickness from less than an inch to over an inch in some areas. In a follow-up telephone conversation with the pilot, he characterized the ice that day as "sticky" and hard to get rid of. AIRPORT INFORMATION Wray Municipal Airport was a public, uncontrolled airport located in class Echo airspace 2 miles northwest of Wray, Colorado, at 40 degrees, 6 minutes, 1.1 seconds north latitude, and 102 degrees, 14 minutes, 27.4 seconds west longitude, at a surveyed elevation of 3,667 feet. The airport had two available instrument approaches at the time of the accident; area navigation (RNAV)/GPS approach for runway 17, and an RNAV/GPS approach for runway 35. The RNAV/GPS approach for runway 17 has an initial approach fix, for arrivals from the west, at ETUDE (located 10.2 miles northwest of the accident location). The approach directs aircraft from west to east at ETUDE at an altitude of 5,500 feet and a bearing of 077 degrees to the COLOD fix. At COLOD, the approach course turned to the south on a bearing of 172 degrees and an altitude of 5,000 feet. The final approach fix, TECOB (located 1,885 feet south of the accident location), was 4.4 miles from K2V5. According to the airport manager, no one was "manning" the airport radio or Unicom the morning of the accident and no radio communications were witnessed or recorded with the accident airplane. WRECKAGE AND IMPACT INFORMATION The accident site was located in an open dormant hay field. The accident site was at an elevation of 3,716 feet msl and the airplane impacted on a magnetic heading of 025 degrees. The airplane impacted in a near vertical, nose down attitude. The wreckage consisted of the fuselage, empennage, both the left and right wings, and the left and right engine assemblies. A strong odor of jet fuel was present at the crash site. An oblong burn pattern 58 feet wide and 67 feet long extended from the crash site eastward. The right wing exhibited aft accordion crushing along the leading edge. The outboard 2/3 of the wing exhibited exposure to fire and was charred and melted. The right aileron remained attached at the outboard hinge, and was bent and wrinkled. The right engine was partially buried in the ground (approximately 2.5 feet) with 14 inches of one propeller blade exposed. The wing inboard of the engine nacelle was destroyed by fire. The right flap was partially consumed by fire. The forward fuselage, to include the forward cabin and instrument panel was destroyed by impact forces and post impact fire. The inboard 2/3 portion of the left wing was destroyed by fire. The leading edge of the wing displayed aft accordion crushing along the entire length. The left aileron was separated at the outboard hinge, was wrinkled, and charred. The left engine was partially buried in the ground (approximately 3 feet) with a portion of one propeller blade exposed. The left flap was attached and exhibited exposure to heat and fire. Control continuity was established on the right wing from the aileron bell crank to the wing root with two breaks located in follow-up cables. Control continuity was established from the left aileron bell crank to the wing root. A broom straw separation, consistent with overload, was observed on the follow-up cable. The empennage was upright and exhibited twisting and “scorpion tail” characteristics. The right horizontal stabilizer exhibited exposure to heat and fire. The left horizontal stabilizer exhibited accordion crushing along the leading edge and a circular impression in the leading edge outboard of the root. Elevator and rudder cables were continuous. The right main gear was collapsed, broken, and located under the right engine nacelle. The left main landing gear was broken and located under the left horizontal stabilizer. The right and left main landing gear actuators were extended. The flaps appeared to be fully extended. The co-pilot altimeter was located 28 feet east of the wreckage. The Kollsman window displayed 30.31, the altimeter needles showed approximately 2,650 feet. MEDICAL AND PATHOLOGICAL INFORMATION Autopsies were performed on the pilot and second pilot at the Jefferson County Coroner's Office on January 17, 2009, as requested by the Yuma County Coroner’s office. The autopsy revealed the cause of death for both pilots as "massive bodily injury secondary to blunt force trauma." During the autopsy, specimens were collected from both pilots for toxicological testing to be performed by the FAA’s Civil Aerospace Medical Institute, Oklahoma City, Oklahoma (CAMI Reference Number 200900018002 and 200900018002). Tests for carbon monoxide, cyanide, ethanol, and requested drugs were all negative. TESTS AND RESEARCH The wreckage was removed to a hangar located in Greeley, Colorado, and the examination continued on January 18th through January 20th. Honeywell examined the left engine under the observation and direction of the Safety Board. The propeller blades were arbitrarily labeled A, B, and C for identification purposes. Blade “A” was straight, exhibited 90 degree and 45-degree chord wise scratching, and exposure to heat. Blade “B” displayed 45-degree chord wise scratching and was bent outboard of the hub at an approximate 15- to 20-degree angle. Blade “C” was bent at an approximate 45-degree angle from the ¼ span outward and displayed lengthwise scratching. The left engine exhibited exposure to heat and the

Probable Cause and Findings

The pilot’s failure to maintain aircraft control during the approach resulting in an aerodynamic stall and subsequent impact with terrain. Contributing to the accident was the pilot’s improper preflight planning and conditions conducive for structural icing.

 

Source: NTSB Aviation Accident Database

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