Overall Trends
Total, fatal, and serious accidents in the selected range.
Premium research interface
The modern interface for aviation safety intelligence.
Search investigations, review source evidence, monitor watched reports, and trace long-term patterns from one calm, data-first workspace.
63k+
Reports indexed
1940-2026
Coverage
Recent
Last data refresh
Search everything
Fast key and full-text search with live filters, watches, and precise metadata.
Use quotes for exact phrase matches (for example "fuel selector valve").
Featured Report
Safety trends by operating rule
Track fatal and non-fatal accident patterns across Part 91, Part 135, and Part 121 operations.
Loading trend charts…
High-signal investigations
Major cases, deep-report coverage, and investigation media across decades of NTSB history.
Browse the aviation graph
Move quickly by aircraft, airport, operator, and time with indexes built for research, not wandering.
Last Data Update
By Decade
By Month
Aircraft Manufacturer
More manufacturersAirports
More airportsOperators
More operatorsAbout
Aviation safety reports, made easier to study
NTSB Reports is an independent research and search tool for public aviation accident and incident records. It brings NTSB aviation reports, structured fields, docket files, extracted figures, photos, videos, and update history into one searchable interface.
The goal is practical safety education: make it faster to find relevant investigations, compare similar events, review factual records, and understand the evidence behind probable-cause and preliminary reports.
The investigative work and source records belong to the National Transportation Safety Board and the published investigation record. This site is not affiliated with or endorsed by the NTSB.
FAQs
NTSB Report
May 14, 1993 · Air Tractor AT-401 · N4503U
Oconto, NE
Overview
Report Status
Probable Cause
Event Type
Accident
Date
May 14, 1993
Injury Outcomes
1 injury (1 minor injury)
Location
Oconto, NE
Aircraft
Air Tractor AT-401
Tail Number
N4503U
Operator
Olson Air Service
Injuries
Minor
Aircraft Damage
Destroyed
NTSB Number
CHI93LA170
THE PILOT WAS OVER FLYING A FIELD IN PREPARATION FOR A SPRAYING RUN WHEN A RAIN SHOWER OCCURRED. THE PILOT STATED A MICROBURST WAS ENCOUNTERED AND HE DUMPED THE CHEMICAL LOAD IN AN ATTEMPT TO MAINTAIN ALTITUDE. THE AIRPLANE DESCENDED FROM AN ALTITUDE OF APPROXIMATELY 400 FEET TO IMPACT WITH THE TERRAIN. A SURFACE WEATHER REPORT ISSUED 25 MINUTES AFTER THE ACCIDENT FROM THE BROKEN BOW AIRPORT, 19 MILES NORTH-NORTHEAST OF THE ACCIDENT SITE, REPORTED VIRGA SOUTH-SOUTHWEST OF THE AIRPORT.
NTSB Probable Cause
THE PILOT'S INABILITY TO MAINTAIN ALTITUDE AFTER ENCOUNTERING A DOWNDRAFT.
Full Narrative
THE PILOT WAS OVER FLYING A FIELD IN PREPARATION FOR A SPRAYING RUN WHEN A RAIN SHOWER OCCURRED. THE PILOT STATED A MICROBURST WAS ENCOUNTERED AND HE DUMPED THE CHEMICAL LOAD IN AN ATTEMPT TO MAINTAIN ALTITUDE. THE AIRPLANE DESCENDED FROM AN ALTITUDE OF APPROXIMATELY 400 FEET TO IMPACT WITH THE TERRAIN. A SURFACE WEATHER REPORT ISSUED 25 MINUTES AFTER THE ACCIDENT FROM THE BROKEN BOW AIRPORT, 19 MILES NORTH-NORTHEAST OF THE ACCIDENT SITE, REPORTED VIRGA SOUTH-SOUTHWEST OF THE AIRPORT.
Flight
Event TypeAccident
Event Time07:30 CDT
Nearest Airport0nm N
Runway0
Flight Plan FiledNone
Aircraft FireNo
Aircraft ExplosionNo
Aircraft
AircraftAir Tractor AT-401
Tail NumberN4503U
Aircraft CategoryAir
DamageDestroyed
OperatorOlson Air Service
Operating RulePart 137
Engines1
Engine TypeReciprocating
Engine DetailsP&W · R-1340-ANI · Reciprocating · 600
Seats1
People & Injuries
Injury Summary1 injury (1 minor injury)
Fatal0
Serious0
Minor1
Uninjured0
Total1
Crew 1Age 33 · Second Class
Conditions
ConditionsVMC
LightDaylight
Wind200° @ 6 kt
Visibility10 sm
CeilingBroken clouds 5000 ft
Temperature / Dew Point61 F / 50
Altimeter29.00 inHg
Observation Time12:55
Weather SourceWFAC