NTSB Report: Aircraft Collides with Mountainous Terrain in IMC

Casualties unknown • Diablo, CA, US

An aircraft collided with mountainous terrain during instrument meteorological conditions. Witnesses reported normal engine operation prior to the incident, and no mechanical failures were found.

What happened

The airplane impacted mountainous terrain while maintaining a near wings-level attitude during instrument meteorological conditions (IMC). Eyewitnesses observed the aircraft flying over their location and reported that the engine sounded normal at that time. There is no record indicating that the pilot obtained a weather briefing prior to departure.

The investigation

A thorough examination of the aircraft wreckage was conducted to determine the cause of the accident. Investigators found no evidence of mechanical failures or malfunctions with the aircraft systems prior to impact. Both propellers exhibited chordwise scratches and 'S' bending, consistent with the engine operating at high power at the time of impact.

Findings

The primary factors contributing to this accident were the pilot's failure to obtain a preflight weather briefing and the subsequent encounter with IMC in mountainous terrain. The absence of mechanical issues suggests the aircraft was airworthy prior to the collision.

Probable cause

The pilot's failure to obtain a weather briefing and his decision to fly into instrument meteorological conditions, which resulted in controlled flight into terrain.

Frequently asked questions

What happened in the 1993-06-06 Piper PA-23-150 accident near Diablo, CA?

An aircraft collided with mountainous terrain during instrument meteorological conditions. Witnesses reported normal engine operation prior to the incident, and no mechanical failures were found.

What aircraft was involved and where did it happen?

The accident on 1993-06-06 involved a Piper PA-23-150, registration N522T, operated by Norman E. Lamantia, at Diablo, CA.

What was the probable cause of the accident?

The pilot's failure to obtain a weather briefing and his decision to fly into instrument meteorological conditions, which resulted in controlled flight into terrain.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001211X12636. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.

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