Casualties unknown

Aerial Application Aircraft Collides with Terrain During Maneuver (N4385Z)

Opheim, MT, US

On July 14, 1999, a Piper PA-18-150 (registration N4385Z) was involved in an aviation accident near Opheim, MT. Investigators recorded the probable cause as: The pilot's failure to maintain an airspeed above stall speed (Vs), resulting in a stall/mush into the terrain during a course reversal at the end of an aerial application run. Factors include hilly terrain and high density altitude. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.

Sourcesthe U.S. National Transportation Safety Board (NTSB) historical archivePrimary reportUpdated 2026-06-10Data APIEditorial standards

A Piper PA-18 performing aerial application crashed after a course reversal. The pilot had expressed concerns about aircraft performance at altitude and temperature, and reduced loads before the accident.

Incident Overview

The pilot of a 150-horsepower Piper PA-18 returned to an aerial application site after refueling and loading chemicals. During the stop, the pilot expressed concern about the aircraft's limited performance at the current temperature (75–80 degrees Fahrenheit) and altitude (about 3,000 feet MSL). He took on a reduced fuel load and planned to finish the field with two half-loads of chemical rather than one full load. Although witnesses observed him partially filling the fuel tanks, no one saw whether the chemical hopper was completely filled or only partially loaded.

Witness Observations

After returning to the field, witnesses saw the aircraft make a pass in one direction but did not see it return in the other direction. Shortly thereafter, a column of black smoke was seen rising from the field. When witnesses arrived at the site, they found the aircraft where it had stalled or mushed into rapidly rising terrain at a location where the pilot would be making a course reversal just off the end of the field.

Findings

The aircraft was found at the location of the course reversal, having impacted rising terrain. The pilot's earlier concerns about performance limitations and the reduced loads were noted, but no further details about the cause of the accident were provided in the source material.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001212X19373. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.