Air Tractor INC AT-301 accident near Farnsworth, Texas, June 9, 2013
On June 9, 2013, a Air Tractor INC AT-301, registered N4421S, was substantially damaged in an accident during maneuvering (low-alt flying) near Farnsworth, Texas. It was an aerial application (crop spraying) flight under agricultural flying rules (Part 137). No one was hurt; 1 person was on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The partial loss of engine power for reasons that could not be determined because the postaccident engine examination revealed no anomalies.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- June 9, 2013
- Place
- Farnsworth, Texas · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Air Tractor INC AT-301 · all AT-301s on the register
- Registration
- N4421S · no longer on the register · serial 301-0081
- Damage
- Substantial damage
- Flight
- Aerial application (crop spraying) flight · agricultural flying rules (Part 137)
The NTSB's narrative final · quoted from the NTSB record
The pilot of the agricultural airplane reported that, as he was beginning a spray pass, the airplane sustained a partial loss of engine power. He attempted to dump his chemical load but was unable to maintain altitude and executed a forced landing to a field. He said that the engine continued to run smoothly but at a reduced power setting during the event. Postaccident examination of the engine revealed no anomalies that would explain the partial loss of engine power. The temperature and dew point were within a range of susceptibility for carburetor icing during glide and cruise power settings. However, the sudden reduction of power with the engine continuing to run smoothly described by the pilot was not consistent with the gradual reduction in power and rough running typically associated with carburetor icing.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
What happened, in order
- Loss of engine power (partial) during maneuvering (low-alt flying) defining event
The NTSB's findings
- cause Aircraft › Aircraft power plant › (general) › (general) › Malfunction
- cause Not determined › Not determined › (general) › (general) › Unknown/Not determined
Pilot
- Certificate: commercial pilot
- Ratings: multi-engine land; single-engine land
- Medical certificate: Class 2 (without waivers/limitations)
- Seat: sngl
- Injury: no injuries
The aircraft
- Airframe total time: 1,138 hours
- Last inspection: 100-hour inspection, January 10, 2013
- Seats: 1
- Landing gear: fixed
- Engine: Pratt & Whitney R1340 AN-1 (piston); 0 hours total
- Operator: Terhune Flying Service INC
The flight
- Departed from: Farnsworth TX at 5:00 pm
- Destination: Farnsworth TX
- Flight plan: not recorded
Weather at the time
- Light: daylight
- Wind: from 230° at 20 knots, gusting 25
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 79°F (26°C), dew point 59°F (15°C)
- Altimeter: 29.95 inHg
- Observation at 11:55 pm from PYX, 13 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
8 documents, released by the NTSB on January 22, 2014. View them here, or download them; the NTSB redacts some personal details before release, and this site shows the NTSB's own titles rather than its file names.
| # | Document | What it is | |
|---|---|---|---|
| 1 | Record of Conversation with Pilot | PDF, 1 page | View Download |
| 2 | Maintenance Record Excerpts | PDF, 5 pages | View Download |
| 3 | Photo 1 View of Airplane from Right | PDF, 1 page | View Download |
| 4 | Photo 2 View from Right Rear | PDF, 1 page | View Download |
| 5 | Photo 3 View from Left Front | PDF, 1 page | View Download |
| 6 | Photo 4 - View of Engine | PDF, 1 page | View Download |
| 7 | Record of Conversation with Mechanic | PDF, 1 page | View Download |
| 8 | FAA Carburetor Icing Saib | PDF, 3 pages | View Download |
The same docket at the NTSB · documents without a copy here are fetched from the NTSB when you open them.
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.