Casualties unknown

Aircraft Located on Mountain One Week After Departure (N5673P)

June Lake, CA, US

On September 18, 1999, a Piper PA-24-180 (registration N5673P) operated by Joseph W. Burton was involved in an aviation accident near June Lake, CA. Investigators recorded the probable cause as: The pilot's continued VFR flight into known instrument meteorological conditions, including icing, which resulted in an in-flight collision with mountainous terrain. 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 pilot departed on a multi-state cross-country flight but never arrived. The aircraft was found a week later at the 11,760-foot level of a mountain. Ground witnesses reported gusty winds, heavy rain, and thunderstorms. No preimpact mechanical malfunctions were found.

Accident Overview

The pilot departed on a multi-state cross-country flight and was reported missing when the airplane failed to arrive at its destination. The pilot had filed an IFR flight plan the night before departure and obtained a weather briefing, which was substantially correct. However, due to fog, the pilot was delayed from the estimated time of departure and never refiled or opened the flight plan. Civil Air Patrol search aircraft located the wreckage one week after the accident.

Location and Weather

The aircraft was found at the 11,760-foot level of a mountain, approximately 1,000 feet below the peak. The site was about 2 miles south of the route of flight filed in the flight plan. Ground witnesses reported gusty winds, heavy rain, and thunderstorms in the area on the day of the crash, with clouds obscuring the mountaintop where the accident occurred.

Flight Plan and Conditions

The pilot had originally filed for an altitude of 13,000 feet. Pilot reports during the morning and early afternoon indicated that cloud bases were 10,000 to 12,000 feet over the mountains, with higher layers up to 24,000 feet. Conditions were favorable for light to moderate clear and/or mixed icing in clouds and precipitation above 12,000 feet.

Pilot and Aircraft Examination

A review of the pilot's logbook indicated 223 hours of actual instrument time and 71 hours of simulated instrument time. About 4 months preceding the accident, the pilot had logged 3 hours. Examination of the airframe and engine revealed no preimpact mechanical malfunctions or failures.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001212X19793. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.