NTSB Factual Report

HISTORY OF FLIGHT

On May 18, 2011, about 1115 mountain daylight time, a Bellanca 17-30A Viking, N93577, impacted the terrain about 40 miles northeast of Rock Springs, Wyoming. The private pilot and his passenger were killed in the accident, and the airplane, which was owned and operated by the pilot, sustained substantial damage. The 14 Code of Federal Regulations Part 91 personal cross-country flight, which departed Pinedale, Wyoming, about 37 minutes prior to the accident, was en route to Fort Collins, Colorado. At the time of the accident, the pilot was flying through an area of multiple layered overcast and broken cloud formations and light rain. No flight plan had been filed, and there was no report of an Emergency Locator Transmitter activation.

On May 17, the day prior to the accident, at 1217, the pilot contacted the Lockheed Martin Flight Service Station, and advised the briefer that he was at Pinedale, Wyoming, and that he was looking to fly via visual flight rules (VFR) to Fort Collins, Colorado. The pilot told the briefer that he was looking at departing sometime in the following four hours, and then stated that he (the pilot) did not think it was looking "particularly good." The pilot then referred to some raw data weather information that he was looking at while he was on the call, and commented that it appeared to him that there was marginal VFR weather around Lander, Wyoming, and that Rock Springs appeared to be having instrument flight rules (IFR) conditions. The briefer then asked the pilot if he wanted a standard briefing, or just an abbreviated briefing, to which the pilot responded that he would take an abbreviated briefing. The pilot then further commented that to him it looked like the route had mountain obscuration and VFR not recommended type of weather along the way.

The briefer then informed the pilot that Airmen's Meteorological Information (AIRMET) Sierra for instrument flight rules (IFR) was in effect for his proposed route. He also advised him that AIRMET Zulu, for moderate icing from the freezing level up to 22,000 feet, and AIRMET Tango, for moderate turbulence below 18,000 feet were also valid along his route. He also told the pilot that there was a Convective Significant Meteorological Information (SIGMET) for possible thunderstorms that might affect part of his proposed route. The briefer and the pilot then began discussing the current weather and the forecast for specific locations along the route. Then, about five minutes into the briefing, the pilot asked the briefer what the weather for the next day (May 18) was going to look like.

The briefer then told the pilot that the "bad news" was that the trough that was causing the weather activity along the route on the day of the briefing was forecast to stay in the area for another 24 to 36 hours. He then explained that the prognostic charts indicated that the next morning there would be low pressure all along the route, with showers in the morning along the northern part of the route, and snow near the foothills along the southern part of the route. He then informed the pilot that the trend indicated that later in the afternoon there would be thunderstorms along the whole route from Pinedale to Fort Collins. He also advised him that there was a forecast for snow that night (May 17) in Pinedale, and that the expected ceilings in the morning around both Pinedale and Laramie would be around 4,000 feet with a visibility around 5 miles. The pilot then remarked that he could "live with" a 4,000 foot ceiling, and then “dodge the showers."

About 7 minutes into the briefing, the pilot made the statement that he could get out of Pinedale right then, and that it looked like there was about a 3,000 foot ceiling. The briefer responded to that comment by trying to clarify if the pilot wanted him to continue to provide more weather information for that day (May 17), or for the next day. The pilot's response to that query was to tell the briefer to just give him the terminal forecast for the Denver area (for May 17). The briefer gave the pilot part of the terminal area forecast (TAF) for Denver, but was then interrupted by the pilot stating that he had a copy of the TAF in front of him, and that he needed to learn to read it. Then, for about a minute and a half, the pilot asked the briefer questions about what specific numbers, letters, and abbreviations on the TAF meant.

The pilot then told the briefer that they would be making their decision (on whether to go then, or the next day), and then thanked the briefer for his help. The briefer then advised the pilot that there were no temporary flight restrictions or adverse NOTAM's (Notice to Airman) along the route, and then commented that there were some showers already starting north of Walden and South of Laramie. The pilot then asked the briefer if he knew what tops of the showers were at that time, and the briefer advised him that they were between 25,000 and 30,000 feet. A few seconds later the pilot advised the briefer that he was looking out the window, and that it was starting to snow in Pinedale at that time. A few seconds after the pilot’s comment about the snow, the pilot terminated the briefing session.

The next morning the pilot did not contact Flight Service for an update briefing, nor did he make use of the services of either Direct User Access Terminal Service (DUATS) providers (although, according to his wife, he often used the data provided on the National Oceanic and Atmospheric Administration site). The pilot did not file a flight plan for a flight on the morning of May 18, but according to recorded radar data, he did depart Pinedale about 1038, and climbed out on a track of about 148 degrees, leveling off around 9,300 feet mean sea level (MSL) at a point about 17 miles southeast of the airport. The pilot then turned right about 50 degrees, and proceeded on a track of about 188 degrees for about 12 miles. The radar data shows that he then executed a 2-mile diameter right turn of about 270 degrees duration, and continued on a track of about 118 degrees for about 28 miles. He then turned left about 55 degrees, and continued on a track of about 63 degrees for about another 20 miles. Up to that point in time, the pilot had maintained an altitude within about 300 feet plus or minus of 9,000 feet MSL.

About 1110, the pilot turned right to a track of about 128 degrees, and climbed to about 11,000 feet. He continued on that track for about 5 miles, where, according to recorded radar imagery, the airplane encountered the western edge of a series of rain shower bands in an area where icing conditions within precipitation were favorable. About 1114, the airplane entered a descending right turn, during which it descended about 2,800 feet in about 30 seconds (an average rate of about 5,800 feet per minute). The airplane was then lost from radar while passing through 8,000 feet, at a location of 42 degrees, 10 minutes, 41 seconds North by 108 degrees, 47 minutes, 44 seconds West. The airplane impacted the terrain at 42 degrees, 10 minutes, 40.95 seconds North by 108 degrees, 47 minutes, 50.12 seconds West, which was about one-tenth of a mile west of the last radar hit.

While en route, the pilot was not in contact with an Air Route Traffic Control Center (ARTCC), and therefore no one knew that the airplane was missing until the pilot did not arrive at his intended destination, and family members became concerned. Based upon the information provided by the family members, an alert notice (ALNOT) for a missing aircraft was issued.

PESONNELL INFORMATION

The pilot was a 55 year old male who possessed a private pilot certificate with an airplane single engine land rating. He did not hold an instrument rating. His last airman’s medical, a third class, was completed on April 4, 2010. His last flight review was conducted on March 23, 2010. As of the end of December 2010, which was the date of the last completed log book entry found, he had accumulated about 3,040 total flying hours, of which about 1,330 hours was in a Bellanca 17-30A.

AIRCRAFT INFORMATION

The airplane was a 1973 Bellanca 17-30A Viking, serial number 73-30591, with a Teledyne Continental Motors IO-520-K (1) engine, and a three-bladed Hartzell HC-C3YF-1RF propeller. Its last annual inspection was completed on May 18, 2010. At the time of the annual, the airplane had accumulated 4,632.2 hours, and the engine had accumulated 1,423.2 hours since new.

METEOROLOGICAL INFORMATION

The 1054 aviation weather surface observation (METAR) for Rock Springs, Wyoming, which is located about 40 miles southwest of the accident site, indicated winds from 100 degrees at 15 knots, gusting to 19 knots, a visibility of 10 statute miles, light rain showers, a broken ceiling at 1,700 feet, a broken layer at 2,400 feet, an overcast layer at 5,000 feet, a temperature of 06 degrees C (43 F), a dew point of 02 degrees C (36 F), and an altimeter setting of 29.62 inches of mercury.

A review by a National Transportation Safety Board staff meteorologist of the weather conditions in the 8,000 to 15,000 foot range in the area of the accident at the time of the occurrence, indicated that a band of rain showers was moving northward through the area. The freezing level in the area was 8,000 feet, and the recorded radar returns of the precipitation reflected in the area were likely super-cooled liquid water droplets, making icing conditions favorable. An enhanced weather chart indicated that around 1100 moderate icing was likely at 11,000 feet and 13,000 feet. Satellite imagery indicates that cloud tops in the area about 1100 were just below 17,000 feet, and winds from the surface to about 20,000 feet were between 15 and 25 knots. In addition, the 1100 icing severity charts for both 11,000 feet and 13,000 feet show bands of Supercooled Large Droplet (SLD) conditions in the area of the accident. Encounters with SLD conditions typically form larger ice shapes on aircraft structure than normal icing conditions, and do so at a much accelerated rate.

WRECKAGE AND IMPACT INFORMATION

The majority of the airplane’s structure impacted the sandy desert terrain with sufficient energy to create a rounded crater approximately 10 feet in diameter and over 2 feet deep at its center. There was a dirt berm about 6 to 8 inches high along the northern edge of crater, consistent with a generally northern impact track. The majority of the airplane’s structure was accounted for at a location immediately adjacent to the crater, having traveled no more than about 5 to 10 feet after impact. Small portions of the airframe, such as the fuel tanks, had been thrown as much as 200 feet further down the impact tack. Portions of the right wing outboard structure were located on the terrain south of the primary impact site. This structure included the right wing flap, right aileron, right wing tip, the outboard half of the aft right wing spar, and portions of the outboard half of the right forward wing spar. The right flap was located about one-half mile south of the main wreckage, with the aileron, wing spar sections, and wing tip coming to rest anywhere from one-quarter to one-tenth of a mile south of the main wreckage.

Almost all of the structure at the main wreckage site suffered very severe impact damage, with most of the airframe being torn, crushed, and splintered into small pieces. Only the landing gear structure, the left flap, and the left aileron retained anything consistent with their original form. The empennage was identifiable as one unit, but its entire tubular steel structure was bent, twisted, and folded into a form only slight reminiscent of its original design. In contrast, the portions of the structure that contacted the terrain away from the primary wreckage displayed failures of their primary structure or attachment fittings, but showed very little in the way of terrain impact damage. The right flap, which had separated from the wing attach structure, maintained its preimpact form, with only minor terrain impact distortion damage to its most inboard rib. Some sheets of surface paint on both the bottom and top of its structure had torn away, along with one inboard rib-stitch covering tape. Its center pivot bracket remained attached to its structure, and the opposite end of the bracket was still attached to a 6 inch by 10 inch section of wooden wing structure that had torn away from the wing. The wood around the inboard and outboard pivot attach fittings had torn loose from the fittings, and the fittings themselves had remained with the wing structure. The right aileron was still attached to the right aft wing spar by all three of its pivot brackets and its actuator rod. It had maintained its basic shape, but about a one foot section of its trailing edge near its center span had be buckled downward about 3 inches. Also, several large sections of paint had separated from its top surface along much of its span. The portion of the wing spar directly in front of the aileron had two transverse partial fractures running from the bottom to the top of the spar. About five feet inboard of the aileron, the wing spar had fractured abruptly across its entire chord. The right wing tip, which was still attached to a section of the forward wing spar that had fractured between the third and fourth ribs inboard of the tip, revealed no terrain impact damage. It's plywood exterior structure had retained it preimpact form inboard to the most outboard wing rib, and its only sign of distress was the separation of a 1-foot by 3-foot section of its cloth covering on its bottom surface. Also attached to this spar section was the forward half of the second rib inboard form the tip, the forward half of the plywood top skin between the two most outboard ribs, along with the top half of the plywood wing leading edge between the same two ribs. No portion of the spar or the structure attached to it, or any of the other spar sections found in that immediate area displayed any of the extreme terrain impact damage associated with the structure found at the primary wreckage site.

After being recovered from the scene, the wreckage was taken to the facilities of Beegles Aircraft Service in Greeley, Colorado, where further examination of the airplane’s structure and engine were performed. The examination found that the structure recovered from the area immediately adjacent to the impact crater included all eight of the wing spar attached fitting fingers. Of those eight, only the two top fingers on the left wing front spar had failed. An examination of the two failure surfaces did not reveal any evidence of pre-existing fatigue fracture propagation, and both contained 45 degree shear-lips consistent with overload failures. Although the location of most of the fragmented wooden wing spar and wing structure material found at the primary impact point could not be determined, all identifiable fracture surfaces associate with the wing spars were examined for evidence of dry rot or any other form of preexisting deterioration, with none being found. All spar fractures associated with the right wing sections that were located away from the main impact site were inspected for the same anomalies using a ten-power lens, with no anomalies being found.

Due to the level of energy dissipated during the impact with the terrain, flight control continuity and engine/propeller control positions were unable to be determined. The force of the impact also severely damaged the engine and its accessories, and rendered the crankshaft unable to be rotated. Due to the extent of the damage, engine components and accessories could not be tested, and instead were, where possible, disassembled for interior examination. The magnetos, fuel pump, fuel manifold valve, fuel metering assembly, fuel injection nozzles, oil pump, oil pick-up tube/screen, oil filter, oil cooler, spark plugs, cylinder/rocker assembly’s, camshaft, cam followers, crankshaft, alternator, vacuum pump, propeller governor, and propeller were examined for evidence of preimpact anomalies or malfunction. The examination did not reveal any evidence of a preimpact condition that wo

NTSB Probable Cause

The pilot’s decision to continue flight into an area of known adverse weather, which resulted in an accumulation of structural ice that led to a loss of control and in-flight breakup. Also causal was the pilot’s inadequate preflight weather planning.