NTSB Factual Report

HISTORY OF FLIGHT

On May 9, 2011, about 0915 mountain daylight time, an Air Tractor AT-802A, N8523H, sustained substantial damage when it impacted terrain about 11 miles east of the Frank Wiley Field Airport (MLS), Miles City, Montana. The commercial pilot, sole occupant of the airplane, was fatally injured. The airplane was registered to and operated by Taylor Aviation, Fort Benton, Montana, under the provisions of Title 14 Code of Federal Regulations Part 91. Visual and instrument meteorological conditions prevailed in the area and a visual flight rules flight plan was filed for the repositioning flight. The cross-country flight originated from Aberdeen, South Dakota, about 0752 central daylight time, destined for Fort Benton, with an intermediate fuel stop at MLS.

Information provided by the Federal Aviation Administration (FAA) revealed that the operator/owner of the airplane contacted the FAA on the evening of May 9, 2011, after they became concerned when the pilot had not arrived at his intended destination. The FAA subsequently issued an Alert Notification (ALNOT). The Montana Aeronautics Division, United States Air Force, local law enforcement, and local volunteer pilots commenced search and rescue operations throughout the area of the pilot's intended flight path. The wreckage was located by aerial units on the afternoon of May 10, 2011.

A witness, who was located about 0.3 miles northeast of the accident site reported that while inside her home, she heard the sound of an airplane flying low and fast past her home. She said that the sound of the airplane was very brief and seemed like the airplane was moving very fast from the east to the west. Shortly after hearing the airplane, she heard a "poof" sound and immediately looked outside the window for the airplane. The witness stated that she didn't see the airplane or any smoke in the area. The witness further stated that she observed a cloud layer covering the top of the mountain ridge to the west and noted a light rain mist with good visibility below the layer of clouds.

According to a company representative, the pilot was returning from Wisconsin following the completion of an aerial firefighting contract and was relocating the airplane to Fort Benton.

Information obtained from Lockheed Martin Flight Service revealed that the pilot spoke to a weather briefer at 0733 central daylight time. The pilot filed a VFR flight plan from Aberdeen to Fort Benton with a fuel stop at MLS. The pilot was offered a weather briefing, however, declined and advised the weather specialist that he had the weather information. About 4 minutes later, the pilot contacted Lockheed Martin Flight Service a second time and activated his flight plan; the pilot declined a weather briefing for his intended route of flight.

PERSONNEL INFORMATION

The pilot, age 65, held a commercial pilot certificate with an airplane single-engine land, airplane multi-engine land, and instrument airplane ratings. In addition, the pilot held a flight instructor certificate with airplane single-engine land and instrument airplane ratings. The pilot was issued a second-class airman medical certificate on November 12, 2010, with a limitation that the pilot "must wear corrective lenses." On an Interagency Airplane Pilot Qualifications Approval Record for the Department of Interior, dated February 7, 2011, the pilot reported that he had accumulated 18,824 hours of total flight time, of which 73 hours were simulated instrument and 7.7 hours were in actual instrument flight conditions. The pilot further reported that he had accumulated 172 hours in the previous 12 months and 80 hours within the previous 60 days. The pilot's most recent flight review was conducted in the accident make/model airplane on March 8, 2010.

AIRCRAFT INFORMATION

The single-seat, low-wing, fixed-gear airplane, serial number (S/N) 802A-0162, was manufactured in 2003. It was powered by a Pratt and Whitney PT6A-67AG, serial number PCE-RD0085, rated at 1,350 horse power. The airplane was also equipped with a Hartzell model HC-B5MA-3D, serial number M11276NS, five-bladed adjustable pitch propeller. The airplane was equipped with instruments that allowed for operation in visual flight rules only.

Review of the aircraft maintenance records revealed that the airplane's most recent annual inspection was completed on February 26, 2011, at an airframe and engine total time of 1,406.6 hours.

METEOROLOGICAL INFORMATION

A National Transportation Safety Board (NTSB) staff meteorologist prepared a factual report for the area and timeframe surrounding the accident.

A National Weather Service (NWS) Surface Analysis Chart, issued at 0900, depicted a stationary front just to the southeast of the accident site stretching northeastward into southern Canada. The station models in the vicinity of the accident site and to the west of the stationary front depicted temperatures in the low 50’s Fahrenheit, with temperature-dew point spreads of 3 degrees Fahrenheit or less, northeast wind between 5 and 15 knots, overcast sky cover with light rain and mist. Station models to the east of the stationary front showed temperatures in the mid 50’s Fahrenheit, dew point temperatures near 50 degrees Fahrenheit, an east wind between 5 and 15 knots, overcast skies, and mist. The accident site was located immediately north of the stationary frontal boundary in the cold air sector of the front where low clouds and light precipitation would generally be expected.

The closest weather reporting facility to the accident site was the Frank Wiley Field Airport (MLS), Miles City, located 11 miles west of the accident site at an elevation of 2,630 feet msl. At 0853, the reported conditions were wind from 050 degrees at 11 knots, visibility 2 statute miles, mist, overcast cloud layer at 700 feet, temperature 12 degrees Celsius, dew point 11 degrees Celsius, altimeter setting of 29.62 inches of Mercury, and a variable ceiling from 400 feet to 1,100 feet.

At 0919, a special unscheduled METAR at MLS reported wind from 00 degrees at 12 knots, visibility 2 statute miles, mist, temperature 12 degrees Celsius, dew point 11 degrees Celsius.

The amended NWS Terminal Aerodrome Forecast (TAF) that was valid at 0627 expected wind from 330 degrees at 11 knots, visibility 6 miles with light rain showers, a broken ceiling at 1,300 feet, and overcast skies at 4,500 feet. Temporary conditions between 0600 MDT and 0900 MDT expected visibility of 1 mile with moderate rain and mist, and a broken ceiling at 500 feet.

For further information, see the Meteorological Factual Report within the public docket.

WRECKAGE AND IMPACT INFORMATION

Examination of the accident site revealed that wreckage debris and broken tree limbs were scattered about a 368 foot debris path along an approximate 212 degree magnetic heading from a cluster of damaged 50 to 60 foot tall trees. A portion of the left wing tip and red navigation lens was located below the initial cluster of trees, which was the first identified point of contact (FIPC) at an elevation of about 3,077 feet msl. The debris path progressively extended along rising terrain to an altitude of about 3,137 feet at the main wreckage. All major structural components of the airplane including all primary flight controls were located along the debris path. Numerous trees of about 18 inches to 20 inches in diameter were topped and damaged at various heights along the wreckage debris path. When viewed from the main wreckage looking to the east, northeast, damage to the trees was progressively lower in height along the debris path from the FIPC to the main wreckage.

Examination of the airplane revealed that the fuselage exhibited impact damage to the hopper, forward portion of the cockpit, and the bottom of the fuselage structure. The fuselage structure was separated just aft of the baggage compartment. The instrument panel was displaced forward into the hopper. The chemical hopper exhibited impact damage and was partially separated from the fuselage. The engine firewall remained attached to the forward portion of the hopper and was buckled throughout. The area surrounding the cabin area was mostly intact and undamaged.

The right forward wing spar remained attached to the fuselage at the attachment points. The right forward wing spar was bent aft. The right wing structure was completely separated from the right forward wing spar. The left forward wing spar remained attached to the fuselage at the attachment points. The left forward wing spar was partially curled around the fuselage structure and bent forward. The left wing structure was completely separated from the left forward wing spar.

Flight control continuity was established from the cockpit controls to all primary flight control surfaces. Various areas of separations within the control cables and torque tubes were observed. All areas of separation were found consistent with overload separations. An elevator trim actuator was damaged and prevented determination of its position.

The engine exhibited impact deformation to the external housings and exhibited no fire damage. The reduction gearbox forward housing was separated. Circumferential contact signatures to the compressor turbine vane ring, first stage power turbine vane ring, first stage power turbine shroud, and the first stage power turbine was noted. The reduction gearbox propeller shaft coupling webs were deformed in a torsional direction.

The propeller assembly remained attached to the engine propeller flange. The propeller blades were labeled one, two, three, four, and five, for documentation purposes. The number one blade was separated from the propeller hub. The propeller blade was twisted from about mid span and trailing edge ripples. The outboard portion of the propeller blade tip was separated. Propeller blade two was separated from the propeller hub and exhibited a ripple along the trailing edge about 10 inches inboard from the blade tip. The blade also exhibited a slight twist throughout opposite direction of rotation. Propeller blade three remained attached to the propeller hub and was bent aft about mid span and twisted opposite direction of rotation. The propeller blade exhibited leading edge gouging and propeller blade tip polishing on the blade face. Chordwise scratching was observed on the leading edge near mid span of the propeller blade.

Propeller blade four remained attached to the propeller hub and was bent aft about 90-degrees, about 12 inches outboard of the propeller hub. Gouges were observed throughout the trailing edge. A portion of the propeller blade tip was separated. Chordwise scratches were observed throughout the leading edge of the propeller blade. Propeller blade five remained attached to the propeller hub and was bent and exhibited a slight blade twist opposite direction of rotation. A ripple within the trailing edge was observed near the propeller blade tip. One of the five propeller blade counterweights was separated. The propeller hub piston, spring, and dome were separated and exhibited impact damage. The propeller spinner exhibited a heavy amount of impact damage.

A postaccident examination of the airframe and engine revealed no evidence of pre impact mechanical malfunctions or failures that would have precluded normal operation.

MEDICAL AND PATHOLOGICAL INFORMATION

The Custer County medical examiner conducted an autopsy on the pilot on May 10, 2011. The medical examiner determined that the cause of death was “...Multiple blunt traumatic injuries”

The FAA's Civil Aeromedical Institute (CAMI) in Oklahoma City, Oklahoma, performed toxicology tests on the pilot. According to CAMI's report, carbon monoxide, cyanide, volatiles, and drugs were tested, and had negative results.

TESTS AND RESEARCH

A Garmin GPSmap 496 hand-held GPS was located within the main wreckage. The GPS and Satloc system data card was sent to the National Transportation Safety Board Vehicle Recorders Laboratory, Washington, D.C. for further examination.

The Garmin GPSMAP 496 was found in good condition. Power was applied to the unit using NTSB laboratory equipment. Device startup was consistent with normal operation and GPS data was downloaded using normal methods and Garmin’s Mapsource software.

The data for the accident flight showed that following the airplane's departure from Aberdeen, the flight continued on a northwesterly course between recorded GPS altitudes between 1,300 and 5,800 feet mean sea level (msl). About 1 hour and 29 minutes later, the data depicted a left turn to a southwesterly course from a GPS altitude of 5,869 feet followed by a descent to an altitude of about 3,819 feet. About 8 minutes later, the data showed the flight path turn to a northwesterly course, with altitude varying between 3,805 and 3,054 feet, with numerous climbs and descents noted over a 23 minute time frame. The data depicted an approximate 30-degree right turn that was initiated from an altitude of about 3,054 feet to an altitude of about 3,241 feet before turning left to a westerly heading 1 minute later. The flight continued on a westerly heading for about 2 minutes and then turned to the right. The data showed that about 1 minute later, the path showed a left turn to the southwest at an altitude of about 3,406 feet. The last recorded data point was recorded at an altitude of about 3,284 feet. The accident site was located about 0.15 miles southwest of the last recorded GPS position.

NTSB Probable Cause

The pilot's continued visual flight rules flight into deteriorating weather conditions in an airplane not equipped for instrument flight, which resulted in a collision with terrain.