N4126TAir Tractor AT-802A · 2007

On May 23, 2012, at 1049 central daylight time, an Air Tractor Inc. AT-802A airplane, N4126T, and a Grumman G-164C airplane, N996QC, collided in flight while maneuvering east of Sedgwick, Arkansas. The commercial pilot on board the Air Tractor was fatally injured, and the commercial pilot on board the Grumman received serious injuries. Both airplanes were substantially damaged. Both flights were being conducted under the provisions of 14 Code of Federal Regulations Part 137 as aerial application flights. Visual meteorological conditions prevailed at the time of the accident. The Air Tractor departed a private strip near Bono, Arkansas, at 1048, and was operating locally. The Grumman departed a private strip near Light, Arkansas, just prior to the collision and was also operating locally.

The pilot of the Grumman reported that he approached the field from the northeast with the intention of starting a spray run on the south side of the field, traveling to the southwest. He observed several other airplanes in the area; however, he did not see the Air Tractor. He stated that upon completing 50% of his first spray pass, his airplane and the Air Tractor collided. The pilot of the Grumman added that the field he was spraying and the field that the Air Tractor was flying over were separated by two field roads and a drainage ditch approximately 100 feet wide.

The Air Tractor departed a private strip with the intention of applying herbicide to a rice crop south of and bordering the field being sprayed by the Grumman.

Global positioning system (GPS) data recovered from the Air Tractor depicted the Air Tractor’s flight from the time of departure from the private airstrip at 1048:07 until the time of the accident. The flight track proceeded to the east for approximately 30 seconds and then turned to the north. The GPS track depicted that, just prior to the accident, the Air Tractor was flying to the north. The altitude track for the GPS started at 55 feet (GPS altitude), with an increase in altitude to 135 feet, followed by a decrease in altitude. The last altitude recorded was 110 feet. The altitude over the target rice field started at 121 feet and descended to 113 feet.

After the collision, the Air Tractor continued several hundred feet to the north, impacted terrain, and came to rest inverted. The Grumman continued several hundred feet to the west, impacted terrain, and came to rest on its left side. There were no ground witnesses to the impact, nor was radar data available. Neither pilot was receiving radar flight following services, nor were they in voice communications with one another. There was no requirement for them to be in voice communications with each other or under radar flight following.

Air Tractor Pilot

The pilot of the Air Tractor, age 51, held a commercial pilot certificate with ratings for airplane single and multiengine land, instrument airplane, and rotorcraft-helicopter. He was issued a second class airman medical certificate on April 3, 2012. The certificate contained the limitations “Not valid for any class after April 30, 2013” and “must have available glasses for near vision.”

On his most recent insurance application dated October 20, 2011, the pilot reported 15,674.5 hours total time; 14,128.3 hours of which were logged in agricultural operations. He reported 790 hours total time in the AT-802 and 490 hours within the previous 12 months. The pilot had successfully completed the requirements of a flight review in September of 2011. The accident report form submitted by Miles Flying Service reported that the pilot had logged 15,800 hours; 916 of which were in the accident airplane make and model. The pilot’s most recent application for an airman medical certificate, dated April 3, 2012, estimated 16,500 hours total time; 75 hours of which were in the previous 6 months.

Grumman Pilot

The pilot of the Grumman, age 55, held a commercial pilot certificate with airplane single and multiengine land, instrument airplane, and rotorcraft-helicopter ratings. He was issued a second class airman medical certificate on February 29, 2012. The certificate contained the limitation “Must wear corrective lenses. Not valid for any class after 2/28/2013.”

The pilot reported that he had logged 17,320 hours total flight time; 11,668 hours of which were in the make and model of the accident airplane. The pilot had successfully completed the requirements for a flight review on December 2, 2011.

Air Tractor

The Air Tractor AT-802A (serial number 802A-0261), predominately yellow in color with blue striping, was manufactured in 2007. It was registered with the Federal Aviation Administration (FAA) on a special airworthiness certificate for restricted operations. A Pratt and Whitney PT6A-65AG engine rated at 1,295 horsepower powered the airplane. The engine was equipped with a 5-blade, Hartzell propeller.

The airplane was registered to and operated by Miles Flying Service, Inc., and was maintained under an annual inspection program. A review of the maintenance records indicated that an annual inspection had been completed on April 24, 2012, at an airframe total time of 3,381 hours.

Grumman

The Grumman G-164C (serial number 19C), predominately yellow in color, was manufactured in 1978. It was registered with the FAA on a special airworthiness certificate for restricted operations. A Garrett TPE331-10 engine rated at 940 horsepower powered the airplane. The engine was equipped with a 4-blade, Hartzell propeller.

The airplane was registered to HDS Inc., operated by Kin-CO Ag Aviation, Inc., and was maintained under an annual inspection program. A review of the maintenance records indicated that an annual inspection had been completed on March 20, 2012, at an airframe total time of 4,103.3 hours.

The closest official weather observation station was Walnut Ridge Regional Airport (KARG), Walnut Ridge, Arkansas, located 10 nautical miles northwest of the accident site. The elevation of the weather observation station was 279 feet mean sea level. The routine aviation weather report (METAR) for KARG, issued at 1055, reported wind from 170 degrees at 8 knots, visibility 10 miles, sky condition clear, temperature 26 degrees Celsius (C), dew point temperature 8 degrees C, altimeter 29.89 inches.

At 1045, the sun was at 108 degrees azimuth and 57 degrees altitude.

Air Tractor

The Air Tractor was equipped with a Hemisphere GPS MD Intellistar CPU (serial number 1024-11463-0011) and a Del Norte Technology Intelliflow Controller (serial number 503226). The devices were sent to the National Transportation Safety Board (NTSB) Vehicle Recorders Laboratory in Washington, D.C., for data extraction. The Del Norte Intelliflow controller was not capable of recording data. The Hemisphere GPS MD Intellistar CPU was capable of recording log and geolocation data on an internal compact flash (CF) card. The unit was disassembled and the internal CF card recovered. Log files were recovered using the vendor proprietary MapStar application. A flight track for the accident flight was recovered. Track log data included the following parameters for each recorded data point: GPS date, GPS time, latitude, longitude, and GPS altitude.

Grumman

The Grumman was equipped with a Hemisphere Intelliflow Controller (serial number 810756) and a Del Norte Technology GPS Measuring Unit (GMU) I/F 2 (serial number 901250). The devices were sent to the NTSB Vehicle Recorders Laboratory in Washington, D.C., for data extraction. The Hemisphere Intelliflow Controller was not capable of recording data. The Del Norte GMU was capable of recording data on an internal CF card; however, the unit was not equipped with the card.

The accident scene consisted of two debris fields – one which extended to the north and one that extended to the west, both of which initiated at the same point. The center point of the debris field contained torn metal, paint chips, and fabric from both the Air Tractor and the Grumman. The debris field which extended to the north contained mostly components from the Air Tractor. The debris field which extended to the west contained mostly components from the Grumman.

The area where both wreckages came to rest was characterized by level terrain, vegetated with trees, bushes, and rice. Both wreckages came to rest in the rice field which was being dusted by the Grumman. A raised berm with two field services roads and an irrigation canal separated the north and south rice fields. Trees and bushes lined the irrigation canal.

Air Tractor

The main wreckage of the Air Tractor was located to the north of the center point of the debris field and included the fuselage, engine, propeller assembly, both wings, and the cabin. The wreckage came to rest inverted. The propeller assembly separated and was located just forward of the engine. The engine, propeller, and cowling exhibited evidence of exposure to heat and fire.

The fuselage came to rest inverted. The upper portion of the cabin area separated and was located in the debris field. The skin and the aft portion of the fuselage were covered in dirt and an oily substance and were partially separated.

The right wing remained attached to the fuselage and included the right flap assembly. Approximately 7'6" of the right wing and right flap were crushed from the outboard tip of the wing, towards the fuselage in an accordion manner. The right aileron separated from the right wing and was located in the initial portion of the debris field. The forward right wing spar was crushed and bent. The aft wing spar was fragmented and partially separated.

The right wing contained multiple tears in the wing skin consistent with propeller strikes. The first tear was located 5'5" outboard from the wing sidewall and was 1'1" long. The tear was narrow and was directionally bent on the bottom of the wing skin in an upward direction. The second tear was located 6’5” outboard from the wing sidewall and was 11” long. The third tear was 7'6" outboard from the wing sidewall and was 4'3" long. Due to the fragmentation of the wing it was difficult to establish the exact width of the tear. The fourth tear was located 9'8" outboard from the wing sidewall and was 3'2" in length. The flap actuator was found properly installed in a position consistent with a fully retracted flap position.

The right aileron push and torque tubes were continuous from the cabin outboard to a separation point. The separation point was in line with the damage consistent with the propeller strike. The leading edge of the right wing was crushed up and aft. Dark transfer marks consistent with rubber were noted on the wing directly beneath the main landing gear. The right main landing gear remained attached and was unremarkable.

The left wing remained attached to the fuselage and included the left flap and left aileron. The wing was covered in dirt. Approximately 15 feet of the inboard portion of the left wing was unremarkable. The outboard 11 feet of the left wing was bent down and wrinkled. Both the aileron and flap were bent and wrinkled. The left aileron push and torque tubes were continuous from the cabin out board to the aileron control.

The engine remained attached to the fuselage. The cowling was bent and wrinkled. The forward portion of the cowling exhibited melted paint and exposure to heat and fire. The propeller assembly separated from the engine at the propeller flange; however all five propeller blades remained attached to the propeller hub. For identification purposes, the propeller blades were labeled “A,” B,” “C,” “D,” and “E.” Blade “A” was bowed aft, covered in oil and dirt, and exhibited leading edge polishing. Blade “B” was bowed aft, covered in oil and dirt, and exhibited leading edge polishing. Blade “C” was bent aft 90°, covered in oil and dirt, and exhibited leading edge polishing. The trailing edge of Blade “D” exhibited a 4” tear starting 10 inches inboard from the blade tip. Approximately 6” of the trailing edge of the blade tip separated. The blade was bowed 90° and exhibited leading edge polishing. Blade “E” exhibited exposure to heat and fire and was bowed and twisted.

The fuselage included the cabin and instrument panel. The instrument panel was fragmented. The flight control cables for the elevator and rudder controls were continuous from the cabin, aft to the point of separation at the empennage.

A ground scar extended from the main wreckage 40 feet south to a berm. A portion of the leading edge of the right wing, the right wing spar, bent and torn metal, a portion of the instrument panel, torn composite material, and various personal effects were located in the debris field of the ground scar. The scar continued from the berm 62 feet to a portion of the canopy structure. A second ground scar was located to the south of the first and was 23 feet long, and 3 feet wide.

The empennage was 25 feet south from the end of the second ground scar and included the left horizontal stabilizer and elevator. The remaining portion of the elevator control remained attached to the empennage. The leading edge of the horizontal stabilizer was bent and crushed in, and the elevator was bent and wrinkled. The lower portion of the vertical stabilizer was located 30 feet south of the empennage. The leading-edge of the vertical stabilizer was crushed aft. The tip of the vertical stabilizer was located 7 feet south of the stabilizer.

The top half of the rudder was located south of the empennage. Yellow and turquoise paint transfer, in a horizontal direction, was located on the lower trailing edge of the rudder. The tail wheel assembly was located just west of the rudder. The bottom portion of the tire had been cut from the tire and was not present. The point of separation was consistent with the contact from a propeller blade.

The right elevator and horizontal stabilizer were located south of the top half of the rudder. The stabilizer/elevator assembly was bent and buckled diagonally, and exhibited yellow and turquoise paint transfer on the lower bottom end of the control surface. The aileron counterweight and the right wing tip were also located in this portion of the debris field. The right wing tip exhibited yellow and turquoise paint transfer.

The left hand interplane strut and a portion of the propeller blade from the Grumman were located in the debris field near the right stabilizer of the Air Tractor. The wing strut was bent approximately mid-span and exhibited blue paint transfer. The propeller blade was labeled “A” for identification purposes and measured 32 inches in length. Dark rubber transfer was present on the face of the blade consistent with tire rubber. A portion of the wheel hub from the Air Tractor was found adjacent to this piece of propeller blade.

A portion of the rear spar of the right wing, an outboard portion of the leading edge of the right wing, the right wing tip, trailing edge ribs, and several fragmented portions of the right aileron were all located in the southern portion of the debris field. The inboard portion of the aileron was 61 inches long and exhibited several penetrating tears which originated on the bottom of the aileron control. The center section of the aileron was located 30 feet south of the inboard portion of the aileron and measured 33 inches. The separation points were clean-cut consistent with a propeller strike.

Grumman

The lower left wing from the Grumman was located 35 feet north of the start of the debris field. This portion of the wing included a 50 inch long portion of the aileron. The attach arm for the aileron was located just north of the lower aileron and exhibited blue paint transfer. The upper aileron was located just to the east of the attach arm and was bent up and mid-span. This piece was followed by the upper left wing which measured 105 inches in length and exhibited torn fabric. The lower outboard left wing tip separated and exhibited torn metal at the separation point.

A large section of dead vegetation, consistent with fuel blight, was located to the west of the fragmented portions of the left wing. A ground scar was located within the dead vegetation measuring 46 feet long and 40 feet wide. The left fuel tank was located just west of the area of dead vegetation.

A 60 inch long portion of the wing was located to the west of the dead vegetation. The leading edge was crushed and the trailing edge was wrinkled. A long narrow ground scar followed this piece with a northwest vector. This ground scar was 20 feet long, terminated with yellow paint chips, and then changed directions to the west for an additional 12 feet. The propeller assembly was located at the end of this ground scar.

The propeller blades were labeled “A”, “B”, “C”, and “D” for identification purposes. Blade “A” separated from the propeller assembly and was located in the debris field. Blade “B” exhibited leading edge gouges, chordwise scratches on the blade face, and was twisted and bent. Blade ”C” was bent aft and exhibited yellow paint transfer on the blade face. The tip of the blade was missing. Blade “D” was embedded in the ground and bent. Blade “A” was in two pieces and separated from the propeller assembly at the hub. The outboard piece exhibited chordwise scratches and was missing a portion of metal measuring 5.5 inches long from the leading edge. The inboard portion exhibited black and yellow transfer on the face of the blade.

A ground scar continued from the propeller assembly 90 feet west to the main wreckage. A wing tip, torn metal, fragmented Plexiglas, and engine components were located in the debris field between the propeller and the main wreckage. The engine separated from the airframe and was located 35 feet to the southeast of the main wreckage.

The main wreckage included the inboard portion of the upper and lower left wing, the empennage, fuselage, main landing gear assembly, and the right wing. The main wreckage came to rest on its left side. The upper right wing was broken into two large sections and came to rest under the fuselage of the airplane. The right aileron separated and was bent at mid-span 180 degrees. The lower right wing remained partially attached. The main wreckage included the upper aileron and attach strut. The aileron cables were continuous from the aileron inboard to the cabin. The entire wreckage was covered in dirt.

The fuselage forward of the cabin area was crushed and fragmented. The aft portion of the fuselage skin and belly of the fuselage was wrinkled. The bottom portion of the fuselage was covered in oil and dirt. The landing gear separated and came to rest adjacent the main wreckage. The hopper was compromised and the spray booms separated.

The empennage included the right and left horizontal stabilizer, the right and left elevator, the vertical stabilizer, and rudder. The outboard tip of the right horizontal stabilizer was wrinkled, but was otherwise unremarkable. The outboard edge of the right elevator was bent up but the elevator was otherwise unremarkable. The upper leading edge of the vertical stabilizer was bent to the right. The top of the rudder was bent to the right and wrinkled. The lower portion of the vertical stabilizer and rudder were unremarkable. The left horizontal stabilizer was bent up at the root and crushed. The elevator separated and was broken in several locations. The rudder cables were continuous from the control surface forward to the cabin. The elevator controls were continuous from the elevator forward to the cabin. The tail wheel remained attached and was unremarkable.

A 43 inch piece of the lower left wing remained attached to the fuselage and was bent 90 degrees. The left wing aileron cable was continuous from the cabin out board to the separation point with the aileron. The leading edge was crushed aft and the skin was wrinkled.

The lower right wing included the aileron and remained partially attached to the fuselage. The leading edge was crushed and twisted. The upper right wing separated into two large pieces and came to rest under the main wreckage. The inboard portion of the right wing measured 105 inches and exhibited leading edge crushing. The outboard portion measured 125 inches and exhibited torn fabric, leading edge crushing, and wrinkled skin. Paint transfer was observed on inboard leading edge of the lower right wing.

The autopsy for the Air Tractor pilot was performed by the State Crime Laboratory, Little Rock, Arkansas, on May 24, 2012, as authorized by the Greene County Coroner’s office. The autopsy concluded that the cause of death was multiple traumatic injuries, and the report listed the specific injuries.

The FAA’s Civil Aerospace Medical Institute, Oklahoma City, Oklahoma, performed toxicological tests on specimens that were collected during the autopsy (CAMI Reference #201200110001). Results were negative for carbon monoxide, cyanide, and ethanol. Testing of the blood and urine revealed amlodipine and yohimbine. Amlodipine is a calcium channel blocker heart medication used in the treatment of high blood pressure. Yohimbine is generally found in over-the-counter dietary supplements.

The Air Tractor was equipped with a FlightCell Pro. According to the manufacturer’s website, this device is used to interface cellular telephones with the radio and intercom system in the airplane. The pilot of the Air Tractor used the FlightCell Pro to interface his cellular telephone with the helmet and radio system in his airplane.

According to a local farmer, he had a telephone conversation with the pilot of the Air Tractor on the morning of the accident. The farmer did not recall the exact time; however, he stated that when he became aware of the accident, he was concerned that the time frame for the telephone call and the accident were similar. The farmer stated that during the telephone conversation, they discussed the new field that the pilot was going to dust for him – the same field that the pilot flew over at the time of the accident. They spoke for several minutes about the new field, and then the call disconnected, consistent with a dropped call. He stated that the dropped or disconnect calls were common in their area and the disconnected call did not concern him. He did not hear anything prior to the dropped call, nor did the pilot express any concerns or discuss what he was doing at the time of the telephone call. The farmer tried to call the pilot back and left a message. He did not speak with the pilot after the call was dropped.

According to the cellular telephone records for the pilot, obtained from AT&T, the pilot initiated a telephone call to the farmer at 1045. The seizure time for the telephone call was 8 seconds and the call duration was 4 minutes and 44 seconds. The records indicated that at 1050, the pilot’s cellular telephone received a call from the farmer. The seizure time of the call was 1 second and the duration of the call was 31 seconds. According to the GPS recovered from the Air Tractor, the airplane departed at 1048:07 and the accident occurred at 1049:41.

Airspeed

Miles Flying Service stated that the airspeed of the Air Tractor at the end of a pass should be approximately 160 miles per hour. The pilot of the Grumman stated that the airspeed of the Grumman during his pass was approximately 135 miles per hour.

Field Surveys

According to the operator of the Grumman, pilots are encouraged to conduct a survey of the field they will be working, prior to flying their first pass. Flying the perimeter of the field is useful for flying a field for the first time as it allows the operator to become familiar with obstacles in the area. If the operator is familiar with the field and has been working the area that day, generally a high altitude survey of the field is conducted to review obstacles and become familiar with other traffic in the area prior to conducting spray operations. In general, the pilot is searching for any hazards to their application area. This survey is generally conducted between 100 and 200 feet above ground level.

Radios

According to the operator of the Grumman, most of the crop dusters in his area are equipped with radios and each operator has their own frequency which they are assigned. This frequency is used to communicate and coordinate with their ground crews. He stated that they have the frequencies of the other operators in their area programmed into their radios and can change frequencies to communicate with the other operators if necessary. If one airplane is transitioning the field of another airplane, the transitioning airplane may change frequencies and announce their location.

Agricultural Aviation Safety Programs

The state of Arkansas requires continuing education in order for the operators to receive and maintain various certifications for agricultural operations. The Arkansas Agricultural Aviation Association (AAAA) sponsors Monday’s Updates, Safety Education Programs, and SAFE Workshops. During these meetings and trainings, pilots have discussions on various safety issues such as surveying fields prior to operations in order to avoid mid-air collisions and controlling chemical drift. Additionally, the AAAA annual convention provides additional safety training through the Professional Aerial Applicators Support System Program which is sponsored by the National Agricultural Aviation Association. Both pilots participated in all of these programs. Both the pilot of the Air Tractor and the pilot of the Grumman participated in these programs.