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Casualties unknown

Non-Instrument-Rated Pilot Encounters IMC, Aircraft Loses Wing During Descent (N5145P)

Guide Rock, NE, US

On August 12, 1991, a Piper PA-24-250 (registration N5145P) operated by Thomas K. Phelps was involved in an aviation accident near Guide Rock, NE. Investigators recorded the probable cause as: SPATIAL DISORIENTATION, AND EXCEEDING THE DESIGN LIMITS OF THE AIRCRAFT. FACTORS RELATED TO THE ACCIDENT ARE INADEQUATE PREFLIGHT PLANNING, VFR FLIGHT INTO IMC, FLIGHT WEATHER AVOIDANCE ASSISTANCE NOT FOLLOWED, EXCESSIVE ALTITUDE, PHYSICAL IMPAIRMENT… 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 2026-07-04Data APIEditorial standards

A non-instrument-rated pilot flying VFR on top encountered IMC at 17,500 feet, lost control, and the right wing separated during an uncontrolled descent. The aircraft lacked oxygen equipment, and the pilot was above 14,000 feet for an hour. Two inflight weather briefings advised avoiding weather, but the pilot continued.

Flight Details

The pilot, who was not instrument rated, was attempting to remain visual flight rules (VFR) on top when he encountered instrument meteorological conditions (IMC) at 17,500 feet. After encountering IMC, the pilot tried to maneuver to remain in visual meteorological conditions (VMC). The aircraft entered an uncontrolled descent, during which the right wing separated from the aircraft.

Oxygen and Equipment

The pilot was above 14,000 feet for one hour. The aircraft was not equipped with oxygen, and no evidence of portable oxygen was found.

Weather Briefings

There was no record of a preflight weather briefing. The pilot obtained an inflight weather briefing 1.5 hours before the crash, during which VFR was not recommended and a route of flight to avoid the weather was suggested. A second inflight weather briefing was obtained 20 minutes before the crash, again suggesting a route to avoid the weather. The pilot continued until he was IMC.

Spatial disorientation

Frequently asked questions

What happened in the 12 Aug 1991 Piper PA-24-250 accident near Guide Rock, NE?

A non-instrument-rated pilot flying VFR on top encountered IMC at 17,500 feet, lost control, and the right wing separated during an uncontrolled descent. The aircraft lacked oxygen equipment, and the pilot was above 14,000 feet for an hour. Two inflight weather briefings advised avoiding weather, but the pilot…

What aircraft was involved and where did it happen?

The accident on 12 Aug 1991 involved a Piper PA-24-250, registration N5145P, operated by Thomas K. Phelps, at Guide Rock, NE.

What was the probable cause of the accident?

SPATIAL DISORIENTATION, AND EXCEEDING THE DESIGN LIMITS OF THE AIRCRAFT. FACTORS RELATED TO THE ACCIDENT ARE INADEQUATE PREFLIGHT PLANNING, VFR FLIGHT INTO IMC, FLIGHT WEATHER AVOIDANCE ASSISTANCE NOT FOLLOWED, EXCESSIVE ALTITUDE, PHYSICAL IMPAIRMENT (ANOXIA/HYPOXIA), AND LACK OF TOTAL INSTRUMENT TIME.

More accident analyses

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001212X17802. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.