Casualties unknown

1988-05-29: Cessna 421C (N98683) — John D. Mac Donald — Shaver Lake, CA

Shaver Lake, CA, US

On May 29, 1988, a Cessna 421C (registration N98683) operated by John D. Mac Donald was involved in an aviation accident near Shaver Lake, CA. Investigators recorded the probable cause as: INFLIGHT ENCOUNTER WITH FORCASTED SEVERE ICING AND TURBULENCE BEYOND THE CAPABILITY OF EITHER THE AIRCRAFT OR THE PILOT , WHICH LED TO AN INFLGIHT LOSS OF CONTROL. 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 1781061362Data APIEditorial standards

A pilot with limited experience in the aircraft and high-altitude flight ignored weather warnings and flew into a mountain wave area, resulting in a steep nose-down impact.

Aircraft and Pilot Information

The pilot purchased the aircraft approximately one month prior to the accident. He had limited experience in the specific aircraft type and limited exposure to high-altitude flight and associated weather phenomena.

Weather Briefing

The pilot obtained two weather briefings for the flight. During both briefings, he was advised of forecast and pilot-reported conditions of moderate to severe mixed icing and turbulence associated with a mountain wave on the eastern side of the Sierra Nevada mountains.

Flight Path

Instead of following his intended route along the western side of the mountains, the pilot chose a direct route that placed the aircraft on the eastern side of the Sierra Nevada.

Accident Sequence

Radar data established the track of the aircraft. The data showed the aircraft in cruise at 16,500 feet until about one minute prior to the accident. The aircraft then climbed to 17,200 feet before disappearing from radar. The last radar target was observed about two miles from the impact location. The aircraft impacted terrain in a steep nose-down descent.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001213X25720. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.