Casualties unknown

Glider Stall During Landing Approach (N1239S)

Fremont, CA, US

On November 11, 1983, a Schweizer SGS 2-33A (registration N1239S) was involved in an aviation accident near Fremont, CA. Investigators recorded the probable cause as: The pilot's failure to maintain adequate altitude while maneuvering in heavy sink conditions, resulting in a stall during the final approach. 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 2026-06-20Data APIEditorial standards

A glider pilot attempted to return to the airport after encountering heavy sink, but ran out of altitude and stalled just short of the runway.

What happened

The aircraft was launched via aero tow to an altitude of 3,000 feet mean sea level. After being released approximately five miles from the departure airport, the pilot engaged in thermaling for roughly five minutes. The pilot then descended to 2,300 feet mean sea level and turned back toward the airfield.

During the return flight, the glider encountered heavy sink conditions. The pilot lacked sufficient altitude to reach the runway. An attempt was made to stretch the glide path to extend range. The glider stalled at an altitude of 20 feet above ground level, approximately 100 yards from the airport.

The investigation

The examination focused on the flight dynamics and environmental conditions leading to the stall. The pilot's inability to maintain adequate altitude due to meteorological factors was noted. No mechanical failures were identified as contributing factors.

Probable cause

The pilot's failure to maintain adequate altitude while maneuvering in heavy sink conditions, resulting in a stall during the final approach.

Frequently asked questions

What happened in the 11 Nov 1983 Schweizer SGS 2-33A accident near Fremont, CA?

A glider pilot attempted to return to the airport after encountering heavy sink, but ran out of altitude and stalled just short of the runway.

What aircraft was involved and where did it happen?

The accident on 11 Nov 1983 involved a Schweizer SGS 2-33A, registration N1239S, at Fremont, CA.

What was the probable cause of the accident?

The pilot's failure to maintain adequate altitude while maneuvering in heavy sink conditions, resulting in a stall during the final approach.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001214X45112. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.