N700VXSocata TBM 700 · 1997

On February 18, 2018, about 1505 mountain standard time, a Socata TBM-700A airplane, N700VX, impacted terrain during an instrument approach to Evanston-Uinta County Airport/Burns Field (EVW), Evanston, Wyoming. The commercial pilot and passenger were fatally injured, and the airplane was destroyed. The airplane was privately owned and operated as a Title 14 Code of Federal Regulations Part 91 personal flight. Instrument meteorological conditions existed at the airport, and the flight operated on an instrument flight rules (IFR) flight plan. The flight departed Tulsa International Airport (TUL), Tulsa, Oklahoma, about 1210 central standard time (1110 mountain standard time).

Radar and air traffic control information provided by the Federal Aviation Administration (FAA) captured the accident flight as it progressed. Initially, the pilot filed Centennial Airport, Englewood, Colorado, as the flight's destination. About 20 minutes after takeoff, the pilot requested to change the destination to Pueblo Memorial Airport (PUB), Pueblo, Colorado. An hour and 20 minutes later, the pilot again requested to change his destination to Provo Municipal Airport (PVU) due to weather. At 1353, the pilot requested to make EVW his new destination stating that EVW was below minimums when he departed, but that the weather had improved. At 1422, the controller asked the pilot if he had the weather information for EVW, and the pilot responded that he did.

The pilot requested and was subsequently cleared for the ILS RWY 23 approach to EVW starting at the FBR VOR initial approach fix. The pilot was initially cleared to FBR at 15,000 ft mean sea level (msl) which the pilot acknowledged. However, while proceeding to FBR, the controller issued several low altitude alerts which the pilot initially did not respond to with the airplane having descended down to 14,400 ft msl. The pilot responded that he was bouncing around and the autopilot was trying to maintain 15,000 ft msl.

Later, the airplane was cleared to cross FBR at or above 10,000 ft msl, and then cleared for the ILS 23 approach. At 1459, the airplane crossed the final approach fix and descended for the approach. At 1502:07, the airplane was at 7,300 ft msl, just below the approach's decision height of 7,343 ft, and about 1.6 nautical miles from the runway threshold. The airplane then climbed past 7,700 ft msl and entered a left, 270° turn, during which the airplane climbed and descended. The airplane then entered a right turn before radar contact was lost at an altitude of 7,900 ft msl. The published missed approach procedure included a straight-ahead climb to 7,600 ft, then a climbing, slight left turn toward a designated holding point about 17 nautical miles southwest of EVW.

Several residents heard the airplane and the sound of the impact and called emergency responders, who dispatched to the accident site. A postimpact fire consumed large portions of the fuselage and wings.

According to airplane maintenance log entries and logged instrument flight plans, the pilot had at least 90 hours in the airplane make and model.

The airplane was manufactured in 1997 and was modified under supplemental type certificate with an MT Propeller MTV-21-1-E 5-bladed propeller and a Garmin G600 avionics system, which included digital primary flight and multifunction displays. Standby instruments were available on the right outermost portion of the instrument panel. The most recent maintenance was a 200-hour inspection completed on September 27, 2017, at a Hobbs meter time of 3,966.5 hours. The pilot purchased the airplane in June 2017.

A weather study was conducted by an National Transportation Safety Board (NTSB) meteorologist. At 0432 on the morning of the accident, the National Weather Service (NWS) issued a Winter Storm Warning for Uinta County, which included Evanston, Wyoming, and warned heavy snow was likely to start at 0900, with total snow accumulation of 8 to 14 inches. At 1227, the NWS Storm Prediction Center identified an area of potential convective activity that encompassed the Evanston area. At 1400, an NWS Surface Analysis Chart recorded a cold frontal boundary extending from just south of the accident site through Utah and into Nevada.

At 1420, before the pilot initiated the approach, the conditions reported by the automated surface observing system (ASOS) at EVW included wind from 290° at 17 knots, 2 miles visibility, light snow and mist, broken clouds at 2,400 ft above ground level (agl), overcast clouds at 3,600 ft agl, temperature 0°C, dew point -2°C, and an altimeter setting of 29.47 inches of mercury. Peak wind was observed from 260° at 32 knots at 1401.

About the time the airplane passed the intermediate fix on the approach, the ASOS reported 3/4-mile visibility with light snow and mist and a broken ceiling at 700 ft agl. Twelve minutes later, and prior to the airplane crossing the final approach fix, the ASOS reported 1/4-mile visibility with snow, freezing fog, and a vertical visibility of 800 ft. Of note, the minimum weather needed to fly the ILS RWY 23 approach is 200 ft and 1/2-mile visibility for all category of aircraft. About the time the airplane began the missed approach, the ASOS reported wind from 350° at 14 knots, 1/2 mile visibility in snow and freezing fog and a vertical visibility of 800 ft.

A review of the 1- and 5-minute interval recording of ASOS data indicated IFR to low instrument flight rules (LIFR) conditions, gusty surface winds, light to heavy snow, and ceilings between 700 to 1,400 ft agl at the time of the accident.

A High-Resolution Rapid Refresh model sounding indicated the possibility of low-level wind shear from the surface to 9,500 ft msl and clear air turbulence above 8,000 ft msl.

A search of official weather briefing sources (such as Leidos Flight Service and Direct User Access Terminal Service) revealed that the pilot did not request a weather briefing from those sources. However, a search of archived ForeFlight information indicated that the accident pilot received a weather briefing package from ForeFlight at 1934 the day before the accident, prior to the release of the significant weather. Most of the information related to the winter storm was issued on the morning of the accident. Foreflight is still able to obtain weather through various means while in flight; however, no record is maintaining of the information accessed. Of note, the pilot changed his destination several times inflight citing weather information. It is not known how the pilot was obtaining those weather updates.

Additional weather information is located in the docket of this report.

The airplane was manufactured in 1997 and was modified under supplemental type certificate with an MT Propeller MTV-21-1-E 5-bladed propeller and a Garmin G600 avionics system, which included digital primary flight and multifunction displays. Standby instruments were available on the right outermost portion of the instrument panel. The most recent maintenance was a 200-hour inspection completed on September 27, 2017, at a Hobbs meter time of 3,966.5 hours. The pilot purchased the airplane in June 2017.

The first impact point was identified in several trees. The right wingtip was found near one of the trees. The angle of impact was estimated at 60° nose low on a magnetic heading of 358°. The ground impact point was identified by a small divot followed by the engine. The main wreckage comprised the fuselage, empennage, and left wing. A post-impact fire consumed most of the cockpit and forward fuselage. The right wing was displaced from the fuselage and came to rest on the right side of the debris area. All major components of the airplane were located at the accident site. Flight control continuity was established from the cockpit controls to all primary flight control surfaces. Flap jackscrew positions were consistent with a flaps setting of 34°, which was consistent with a landing configuration. Landing gear actuator positions indicated that the landing gear were retracted. The avionics and cockpit switches were impact damaged and either partially or totally consumed by the postimpact fire.

The engine was removed and examined. Fire and impact damage precluded functional testing of the major components; however, disassembly revealed circumferential rubbing and smearing of fan discs in multiple stages of the engine, including the compressor and turbine section, consistent with the engine producing power at the time of impact. No preimpact anomalies of the engine were found.

Interview with the Airport Manager

The EVW airport manager stated that the pilot had told him of a flight, several months before the accident, during which the airplane's flight display went blank during an instrument approach. On that day, the weather was marginal visual flight rules with light snow, and the pilot had ForeFlight on his iPad, which he used to make a left turn back toward the northeast and set up to fly the approach again. The pilot said he was going to have an avionics shop troubleshoot the issue. The airport manager did not hear anything further about an avionics problem, and review of the airplane's maintenance log did not find any recorded entry for avionics work.

The airport manager stated that, around 1455 on the day of the accident, he heard what he assumed to be the accident airplane click the mic 5 times, then a few seconds later, click the mic 3 times on the airport's common traffic advisory frequency, consistent with the pilot activating the airport's pilot-controlled lighting system. A few minutes later, he heard a 10-second transmission during which he thought he could hear a woman's voice in the background before the transmission ended. There was no distress call.

Spatial Disorientation

The FAA Civil Aeromedical Institute's publication, "Introduction to Aviation Physiology," defines spatial disorientation as a loss of proper bearings or a state of mental confusion as to position, location, or movement relative to the position of the earth. Factors contributing to spatial disorientation include changes in acceleration, flight in instrument meteorological conditions (IMC), frequent transfer between VMC and IMC, and unperceived changes in aircraft attitude.

The FAA Pilot's Handbook of Aeronautical Knowledge, chapter 16,

Aeromedical Factors," stated, "Under normal flight conditions, when there is a visual reference to the horizon and ground, the sensory system in the inner ear helps to identify the pitch, roll, and yaw movements of the aircraft. When visual contact with the horizon is lost, the vestibular system becomes unreliable. Without visual references outside the aircraft, there are many situations in which normal motions and forces create convincing illusions that are difficult to overcome…Unless a pilot has many hours of training in instrument flight, flight should be avoided in reduced visibility or at night when the horizon is not visible. A pilot can reduce susceptibility to disorienting illusions through training and awareness and learning to rely totally on flight instruments.

An autopsy on the pilot by an independent pathologist revealed mild-to-moderate coronary artery disease with no blood clots and no evidence of a recent or remote heart attack. The pulmonary circulation was unremarkable, but the cerebral circulation was not available for examination. Multiple gallstones were present, but there was no reported obstruction or inflammation. The cause of death was listed as multiple traumatic and thermal injuries.

The FAA's Forensic Sciences Laboratory performed toxicology testing on specimens from the pilot. Results were negative for all tested for substances.