Butte, MT, USA
N4914A
CESSNA T310R
Shortly before embarking on the flight, the instrument-rated pilot filed an instrument flight plan and checked the weather using a computer-based filing system. At that time, the destination airport was reporting visual meteorological conditions, with similar conditions forecast for the planned arrival time. The pilot did not list an alternate airport in the flight plan. About halfway through the flight, the pilot contacted the air traffic controller responsible for the destination airport’s airspace. By that time, the weather conditions at the destination had deteriorated, with reports of snow and fog and visibility below the instrument approach minimums. The controller provided updated weather information and asked the pilot if he wanted to continue with the initial approach. He responded that he did and that he would divert to an alternate airport if necessary. The pilot was then cleared for the approach, and the airplane began to descend toward the initial approach fix (IAF). Shortly thereafter, a scheduled air carrier airplane destined for the same airport contacted the same controller. The controller relayed the weather information, and the crew of that airplane responded that they would delay the approach to see if the weather conditions improved. About that time, the accident airplane reached the IAF and began the approach. The air carrier pilot then requested and received approval to divert to an alternate airport due to the weather conditions. The accident pilot most likely did not hear this exchange because he had switched to the airport frequency. Due to limitations in radar coverage, the air traffic controller was not able to see the airplane once it had descended to the approach altitude. About 4 minutes after the air carrier airplane began to divert, the accident pilot reported that he was performing a missed approach. The controller provided missed approach instructions and asked for the pilot's intentions. The pilot read back the instructions but did not state his intentions. The controller asked if he would like to divert to the alternate airport, and, after a series of delayed and partial responses from the pilot, a call of "Mayday Mayday" was heard on the controller's frequency. For the next 35 minutes, the controller unsuccessfully attempted to contact the pilot. During that period, an air medical flight also canceled a landing approach into the airport due to deteriorating weather conditions. Multiple witnesses reported the sounds of a loud, low-flying airplane northwest of the airport about the time of the landing attempt. The witnesses reported the sudden onset of a gusting wind, heavy snow, low visibility, and ice accumulations during that period. The airplane wreckage was located a few miles from the witnesses, about midway between the airport and the missed approach hold location. The wreckage distribution and flight instrument readings were indicative of a high-speed, steep nose-down, left-turning descent into the ground, with a heading almost opposite the direction of the missed approach route. Engine instrument indications, and both the engine and propeller damage signatures, were consistent with the engines producing similar amounts of power at the time of impact. The airplane was equipped with instruments and systems required for flight in instrument meteorological conditions (IMC) and flight into known icing. Additional equipment included an autopilot and a global positioning system (GPS) navigation and communication transceiver capable of receiving and displaying current weather information via satellite. Impact damage prevented a determination of the operational status of those systems. Available ground-based radar tracking data indicated smooth heading and altitude changes and minimal altitude deviations prior to the pilot being cleared for the approach, consistent with autopilot use. According to the prior owner of the airplane, the autopilot was susceptible to becoming disengaged during turbulent conditions, and, as such, it is possible that at some point during the approach the pilot was forced to revert to flying the airplane manually. Under such circumstances, the pilot's workload would have rapidly increased. Additionally, the likely accumulation of ice on the airplane's airframe would have reduced flight performance and added to his workload as he attempted to monitor the ice accumulation and operate the deice system. The pilot had recently purchased the airplane and likely had minimal solo experience flying it in IMC. The airplane was about 2 months overdue for its annual inspection, and 12 months overdue for its transponder, static, and altitude reporting systems check. However, postaccident examination of the airframe remnants did not reveal any failures or malfunctions which would have precluded normal operation. The engines exhibited indications of wear that would have resulted in a gradual reduction in engine power over its life, rather than a sudden loss of power. Although the severe weather conditions were not forecast, the pilot was accurately advised of the deteriorating conditions by the controller prior to the approach, and he would have had access to airport terminal reports via the airplane's radio and his GPS navigation system. The lack of a filed alternate airport indicates that the pilot was not prepared for the severity of the weather conditions. The airplane was carrying ample reserves of fuel, with enough to return to the departure airport if necessary.
HISTORY OF FLIGHT On March 19, 2011, about 1605 mountain daylight time, a Cessna T310R, N4914A, collided with terrain during a missed approach at Bert Mooney Airport (BTM), Butte, Montana. The pilot was operating the airplane under the provisions of Title 14 Code of Federal Regulations Part 91. The commercial pilot sustained fatal injuries. The airplane sustained substantial damage, and was consumed by a post crash fire. The cross-country personal flight departed Great Falls International Airport (GTF), Great Falls, Montana, about 1520, with a planned destination of Butte. Instrument meteorological conditions prevailed, and an instrument flight rules (IFR) flight plan had been filed. A witness, who was located in his residence at an elevation of about 5,600 feet mean sea level (msl), 3.5 miles northwest of the arrival end of runway 15, reported that snow began to fall in the area about 1540. About 1600 he was located at the east-facing window in his living room, because his attention was drawn to the snow, the intensity of which had increased. He stated that the area is susceptible to snow at this time of year, however, this snow fall was unusually heavy, and obscured his view across the street. The snow was blowing horizontally from west to east, and he continued to watch as it created unusual "eddy effects" as it swirled around his house. He then became aware of a very loud airplane engine sound, so loud that his reaction was to duck. He stated that he lives close to the normal flight path of the airport, and was very familiar with the sound of airplanes; however, this was much louder, and although he could not see the airplane, it appeared to be much closer than usual. He stated that he did not hear the sound of an explosion or impact. Another witness located in his office on the campus of Montana Tech, about 4 miles northwest of the arrival end of runway 15, reported similar weather conditions and aircraft sounds about the same time. By the time he left his office, about 2 hours later, he observed vehicles in the parking lot encrusted with a layer of 1.5- to 2-inch-thick snow and ice. The Federal Aviation Administration (FAA) provided radar and voice communication data for the flight, which revealed that the pilot was receiving radar vectors from the Salt Lake Air Route Traffic Control Center (ARTCC). About the time of the accident, the ARTCC controller for the sector, which included BTM, was providing radar vectors for multiple aircraft, including the accident airplane, and a Canadair Regional Jet (CRJ-200) operated SkyWest Airlines as Flight 4658. The SkyWest airplane was also destined for BTM. The radar data revealed a target displaying a 4636 beacon code corresponding to N4914A, 90 miles northeast of BTM at 1530:00. Over the course of the next 19 minutes, the target maintained a track of 205 degrees true, at a Mode C reported altitude of 13,300 feet. At 1549:04, the pilot made a radio transmission to air traffic control reporting his altitude as 13,000 feet. The air traffic controller responded, and asked if the pilot he had checked the weather for BTM. The pilot responded that he was about to, and 27 seconds later, the air traffic control provided weather information for BTM that was recorded at 1538. The controller reported winds of 290 degrees at 9 knots, gusting to 16, with 1/3 mile visibility, snow, fog, few clouds at 800 feet, a broken ceiling of 1,400 feet, and an overcast ceiling at 2,200 feet. The pilot then responded, "We've picked that up, uh that just changed on us in here, in the last little bit." The air traffic controller replied that the weather had recently changed, and that although the visual approach was available earlier, the conditions were now deteriorating. The controller then stated, "Get back to me if you want to continue inbound or go somewhere else." The pilot replied, "...let's plan on going ahead and we'll..., looks kind of scattered and broken where I'm at." The controller asked the pilot to confirm that he wanted to start the initial approach, and the pilot responded, "... let's try that, and then if we have to, we'll go back to Helena." At 1551:01, the controller responded that he observed N4914A established on Victor Airway 113, flying towards EVVER intersection. He then cleared the pilot for the "ILS Y RWY 15" approach, directing him to fly direct to MAGIC intersection, crossing it at or above 12,000 feet. The pilot read back the instructions, and radar data indicated that the airplane then initiated a descent towards MAGIC intersection. The controller then made contact with SkyWest Flight 4658, informing the crew that they were the number two aircraft for the approach. The SkyWest pilot then responded, "We are just talking about what we are going to do here, if we could just stay at three zero zero for a minute that would be better for us." The controller then cleared the SkyWest airplane to maintain flight level three zero zero, and stated, "As you may have heard, the conditions have changed somewhat, now let me know what you would like to do and I will get you a new airport if you need it." About 4 1/2 minutes later the SkyWest pilot reported, "We'd like to start down and get lower just in case the visibility comes up there and we can shoot the approach, but we can't stay for too long, we are going to have to head over to Bozeman in about 5 minutes or so." The controller subsequently cleared the airplane to hold over the Coppertown (CPN) Very High Frequency Omni-directional Range (VOR) at 16,000 feet. At 1558:24, N4914A reached MAGIC intersection at an altitude of 11,150 feet. The controller reported that radar services were terminated, and cleared the accident pilot to switch to the advisory frequency, with instructions that he could call back if he elected to perform a missed approach. The pilot read back the instructions. The target then crossed over MAGIC intersection, and began a right turn to the northwest. The turn was consistent with an entry into the published holding pattern, for the ILS 15 Y Approach. The last radar return from the airplane was recorded 36 seconds later, at 1559:00. That return indicated that the airplane was at 11,200 feet, and on a track of about 330 degrees. Shortly thereafter, the SkyWest pilot called requesting to discontinue the hold, and divert to Bozeman. The controller subsequently cleared the airplane to fly directly to Bozeman. At 1604:24, the pilot of N4914A reported that he was performing the missed approach. The controller then responded with the BTM altimeter setting, instructions to climb to and maintain 15,000 feet, and a request for the pilot's intentions. The pilot then responded that he would begin the climb. The controller asked if he would like to divert to Helena, and after a 10-second pause, the pilot confirmed that he would like to do so. The controller then instructed the pilot to report leaving 12,000 feet, stating that he would be able to pick him back up on radar at that altitude. However, for the next 15 seconds the pilot did not respond. Shortly thereafter, a call of "Mayday Mayday" was heard on the controller's radio frequency. For the next 35 minutes, the controller unsuccessfully attempted to make contact with the pilot of N4914A both on the aircraft emergency frequency, and by utilizing airborne aircraft in the Butte area to relay messages. During that period a Pilatus PC-12 airplane performing an air medical mission also cancelled an approach into BTM, after the controller updated that airplane with the 1653 automated weather report, which indicated winds of 330 at 8 knots, 1/4 mile visibility with snow, freezing fog, broken ceilings at 400 and 900 feet, and overcast at 1,400 feet. PERSONNEL INFORMATION A review of FAA airman records revealed that the pilot held a commercial pilot certificate with ratings for airplane single-engine land, multiengine land, and instrument airplane. He held a third-class FAA medical certificate issued in March 2010, with the limitation that he must wear lenses for near and distant vision. No personal flight records were located for the pilot, and they were presumed to be consumed in the postaccident fire. Examination of the aeronautical experience listed in the pilot's 2010 application for his FAA medical revealed that he reported a total of 1,750 flight hours, with 30 hours logged in the last 6 months. The pilot was issued his private pilot certificate in 1982, and subsequently received his instrument rating in 1988. According to his multiengine rating application, dated April 19, 2003, he had amassed a total of 170 hours of instrument flight experience, 89 of which was logged utilizing a training device. The pilot's aircraft insurance company provided a record of pilot qualifications, which the pilot had completed in July 2010 as part of his application for insurance coverage for N4914A. At that time, he reported a total experience of 1,745 flight hours, 52 of which were in multiengine airplanes. BTM was the pilot's home airport. AIRCRAFT INFORMATION The, six-seat, low-wing, retractable-gear airplane, was manufactured in 1978. It was powered by two fuel injected, turbo-charged, Continental TSIO-520 engines, and equipped with McCauley three-blade, constant-speed propellers. Due to the damage sustained to the airplane, the total flight time could not be determined. Review of the airplane maintenance records revealed that the most recent airframe and engine annual inspection was completed on December 11, 2009, at a total airframe time of 4,259.0 flight hours. At that time the right engine, serial number 176624-R, and the left engine, serial number 176625-R, had accumulated 1809.4 flight hours each since their last overhaul in January 1994. The records documented 11 maintenance events since the December 2009 annual inspection. The last of those was recorded on December 9, 2010. No record of an annual inspection subsequent to the December 2009 inspection, 15 months prior, was located. The most recent documented test of the airplane's transponder, static, and altitude reporting systems was dated February, 12, 2008. FAA regulations require those tests every 24 calendar months. The airplane was equipped with its original NAV-O-MATIC 400B two-axis autopilot, which was configured with a horizontal situation indicator (HSI), and capable of providing flight control necessary for instrument approaches. Original equipment also included the Cessna "Known Icing Conditions" deice system kit, which was comprised of an electric deicing pilot's windshield panel, wing and empennage pneumatic deice boots, heated pitot head and static ports, and propeller deice boots. A supplemental oxygen system tank was located within the wreckage. The airplane was equipped with navigational and flight instruments suitable for flight in instrument meteorological conditions. Additional instrumentation included an L-3 Avionics Stormscope WX-1000 lightning detection system, a Garmin 530AW, Wide Area Augmentation System capable - Global Positioning System (GPS)/Navigation/Communication transceiver, and a Garmin GDL-49 XM Satellite data link transceiver. According to the manufacturer, the GDL-49 is capable of providing weather data delivery to the 530AW unit through use of the Sirius XM Satellite Radio network. The pilot purchased the airplane in July 2010. The prior owner was also the airplane's current mechanic. The prior owner reported that after the sale, he continued to fly the airplane and share the maintenance costs with the pilot. He stated that the pilot would often perform maintenance on the airplane, but under close supervision. METEOROLOGICAL INFORMATION BTM airport was equipped with an automated surface observation system, which disseminated and transmitted Meteorological Aerodrome Reports (METARs) and special reports surrounding the period of the accident. The observations indicated that visual flight rules (VFR) weather conditions prevailed at BTM during the morning hours, including the time of the airplane's departure from GTF, followed by deterioration to IFR, and then low IFR (LIFR) conditions during the flight. LIFR conditions are defined as a ceiling less than 500 feet and/or visibility 1/2 mile or less. At 1518, 2 minutes before the airplane's departure from GTF, a special weather report for BTM was issued indicating winds from 290 degrees at 15 knots, gusting to 23 knots, with 9 miles visibility, scattered clouds at 2,400 feet, and an overcast ceiling at 7,000 feet. Two minutes later another report was issued indicating similar ceilings but with a visibility of 2 miles in light snow, with a temperature of 2 degrees C, and a dew point of minus 3 degrees C. Multiple special reports for BTM were issued throughout the period of the flight, all indicating a rapid decrease in visibility and ceilings, along with gusting and shifting wind conditions. The final special report issued prior to the accident was at 1553, and indicated winds from 300 degrees at 8 knots, with 1/4 miles visibility, snow, freezing fog, broken clouds at 400 and 900 feet, with an overcast layer at 1,400 feet, and a temperature and due point of minus 1 and minus 2 degrees C, respectively. Pilot Reports Four pilot reports (PIREPS) were transmitted for the Montana area surrounding the time of the accident. Two of the reports indicated icing, with the first reporting light to moderate rime ice over Helena (HLN) with no altitude reported. The second report indicated light rime ice at 11,000 feet, 69 miles east of Billings (BIL). Forecasts The forecast during the accident period for the area west of the Continental Divide was for overcast clouds at 8,000 feet msl with tops to 25,000 feet, and widely scattered light rain and snow showers. The southwestern mountain region expected similar conditions with broken clouds at 10,000 feet msl, overcast at 15,000 feet with tops to 25,000 feet with occasional light rain and snow, and isolated thunderstorms with tops to 28,000 feet. AIRMETs (airmen's meteorological information) for the accident period revealed that the accident site was located within an area covered by an advisory for mountain obscuration and icing conditions, and bordered immediately east of one of the areas of expected IFR conditions. The BTM terminal area forecast issued at 1140 MDT predicted VFR conditions from 1500 through 2100 with wind from 250 degrees at 11 knots gusting to 18 knots, visibility better than 6 miles in light snow, with a broken ceiling at 6,000 feet above ground level (agl) in cumulonimbus clouds. Immediately prior to the accident at 1545 and approximately 1/2 hour after, snow began at the airport; the forecast for BTM was amended, with expected IFR conditions at the time of the airplane's arrival. The forecast from 1600 became visibility 1/2 mile in moderate snow and fog, scattered clouds at 800 feet agl, ceiling broken at 1,400 feet, overcast at 2,200 feet. The National Weather Service Current Icing Product (NWS CIP) is an automatically-generated index suitable for depicting areas of potentially hazardous airframe icing. A CIP analysis for 1600 at 10,000 feet resulted in a greater than 50 percent probability of icing conditions at 10,000 feet msl over southwestern Montana and the accident site, with values reaching 70 percent southeast of the accident site near the Wyoming and Idaho border. Weather Briefing The pilot filed an IFR flight plan, and received a weather briefing about 25 minutes prior to departure, utilizing the Computer Sciences Corporation Direct User Access Terminal Service system. The pilot selected a 'low altitude weather briefing' during the session. The data provided during that session included Terminal Aerodrome Forecasts, Severe Weather Outlook, Current weather conditions, and NOTAMs. The pilot filed a plan requesting a route of flight from GTF to HLN to EVVERS intersection, at an altitude of 13,000 feet. He reported a total of 3 hours of fuel on board, and did not indicate an alternate airport destination. Satellite Weather System The pilot maintained a current monthly subscription to the Sirius XM Satellite Radio, XMWX Satellite Weather 'Aviator' service at the time of the accident. Utilizing this subscription, the Garmin
The pilot's loss of airplane control during the missed approach for undetermined reasons. Contributing to the accident was the rapid and unforecast deterioration of the weather conditions to below the landing minimum and the pilot's decision to attempt the approach despite his knowledge of those conditions.
Source: NTSB Aviation Accident Database
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