# NTSB CHI93LA170: Air Tractor AT-401, N4503U, Oconto, NE, May 14, 1993

- Type: NTSB accident investigation
- Classification: Accident · Minor injuries · Limited investigation · Final report
- Date: May 14, 1993, 07:30 local (12:30 UTC)
- Place: Oconto, NE
- Coordinates: 41.140556, -99.759162 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=41.1406&lon=-99.7592&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: Minor injuries
- Injuries: 1 minor
- Status: Completed, report November 15, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 15716
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI93LA170
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/15716/pdf
- Page: https://openairdocs.org/ntsb/CHI93LA170

## Probable cause

THE PILOT'S INABILITY TO MAINTAIN ALTITUDE AFTER ENCOUNTERING A DOWNDRAFT.

## Sequence of events

In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf).

- In flight encounter with weather, maneuvering - aerial application
  - weather condition - downdraft (cause)
- Altitude deviation,uncontrolled, maneuvering - aerial application
  - altitude - not possible, pilot in command (cause)
  - load jettison - performed, pilot in command
- In flight collision with terrain/water, descent - uncontrolled
  - terrain condition - open field

## Analysis

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.

## Aircraft

- Registration: [N4503U](https://openairdocs.org/deregistered/N4503U-2003-07-22), registration cancelled 2003-07-22, S/N 401-0748 (OpenAirDocs)
- Reported make and model: AIR TRACTOR AT-401
- Registry model: [Air Tractor AT-401](https://openairdocs.org/model/air-tractor-at-401) (registry code 0390204) (OpenAirDocs)
- Category: Airplane
- Serial number: 401-0748
- Airframe hours: 1159
- Engines: P&W R-1340-ANI 600 horsepower reciprocating
- Damage: Destroyed
- Flight: Aerial application, Part 137
- Operator: Olson Air Service, Inc.
- Registered owner: Arlen A. Olson
- Airworthiness certificate: Special, Restricted (Special)
- Last inspection: Annual, March 8, 1993, 140 hours before
- Departed: HOLDREGE, NE

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 33; commercial; airplane ratings: single-engine land; medical: class 2, valid medical--no waivers/lim.; seat: center; flight hours: 1,848 total, 247 in this make and model, 1,750 as pilot in command, 179 in the last 90 days, 128 in the last 30 days, 8 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 200° at 6 knots
- Visibility: 10 statute miles
- Lowest ceiling: 5,000 ft broken
- Temperature: 61 °F, dew point 50 °F
- Altimeter: 29.00 inHg
- Observed at: BBW, 19 nm away

## FAA reports on this event (1)

The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs).

- [Accident 19930514013739A](https://openairdocs.org/incident/19930514013739A), May 14, 1993: Airtrc AT401, Oconto, NE, Destroyed. Reported low clouds over spray field and a micro burst caused loss of altitude and ground impact.

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

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