FTW99FA004 · Air Tractor AT-401
Air Tractor AT-401 · Accident: in flight encounter with weather while maneuvering
From 9M2 to an unrecorded destination
Event
- NTSB case
- FTW99FA004
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Accident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- API-reported fatalities
- 1 · all aircraft and ground
- Ground fatalities
- 0
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- General aviation
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Instrument Meteorological Cond
Air Tractor AT-401
- Aircraft type
- Air Tractor AT-401
- Category
- Airplane
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- N4531M
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From 9M2To not recorded
- Aircraft age
- Not recorded
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Part 137: Agricultural
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- Maneuvering · aerial application
- First occurrenceThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- In flight encounter with weather
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Substantial
Cause areas
- Pilot in command › Aircraft control, not obtained/maintained
- Pilot in command › Flight into adverse weather, inadvertent
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
The agricultural airplane, flown by the non-instrument rated commercial pilot, descended into a lake following a loss of control during an inadvertent entry into adverse weather conditions. A 'very dense' fog bank extending from the ground to 300 to 400 feet agl moved rapidly into the area. The National Weather Service reported that throughout northeastern Louisiana, the weather conditions were: winds calm to 3 knots from the north, 1/4 statute mile visibility in fog, ceiling of 100 feet, and a temperature dewpoint spread of 2 degrees Celsius. The pilot had accumulated over 20,000 hours of aerial application flying including over 4,000 hours in the accident aircraft. The aircraft was not equipped for flight into instrument meteorological conditions. No pre-impact anomalies were found with the airframe or the engine.
Probable cause
The pilot's failure to maintain aircraft control during an inadvertent entry into adverse weather conditions. A related factor was the fog.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record FTW99FA004
- Event ID
- 20001211X11251
- Case number
- FTW99FA004
- Dataset
- historical-pre2008
- Source SHA-256
- 89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
Source notes (4)
- Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
- Filled from the NTSB case API where the bulk record had no value: investigation status. Values present in the bulk record are kept.
- The date is the local date, which is the same as the UTC date the NTSB stores.
- API snapshot SHA-256: bee0d67ef9a5a39f3a48f9c0feb4a5b452e452a6832609dbffddaeb39fa0f2aa; retrieved 2026-09-20T22:22:12.368Z.