Glider Crash Due to Premature Release and Deployed Speed Brakes

Casualties unknown • Mattoon, IL, US

A glider instructor released the tow line prematurely at approximately 5 feet because the tug appeared to be struggling, only to discover later that speed brakes were fully deployed during the entire takeoff run.

What happened

The incident occurred while a sailplane was being towed for takeoff behind an aircraft serving as the tow plane. According to the glider instructor, the initial acceleration phase appeared normal. However, as the combination of the tow plane and the glider neared the end of the runway, the instructor observed that the tug seemed to be experiencing difficulty accelerating to the necessary takeoff speed.

Believing the tow aircraft was unable to gain sufficient altitude or speed, the instructor made the decision to release the tow line at an approximate altitude of 5 feet. Following the separation, the instructor turned the glider toward a suitable area for landing. The sailplane subsequently touched down in what was described as a nose-down pancake landing.

Later investigation revealed that the speed brakes and spoilers had been fully deployed during the entire takeoff run and the subsequent short flight. This configuration significantly increased drag, likely contributing to the inability of the tow plane to accelerate normally and the glider's hard landing.

Probable cause

The glider instructor's premature release of the tow line due to a misperception of the tow plane's performance, compounded by the speed brakes and spoilers being fully deployed during the takeoff run.

Frequently asked questions

What happened in the 1986-07-28 Schweizer SGS 2-33A accident near Mattoon, IL?

A glider instructor released the tow line prematurely at approximately 5 feet because the tug appeared to be struggling, only to discover later that speed brakes were fully deployed during the entire takeoff run.

What aircraft was involved and where did it happen?

The accident on 1986-07-28 involved a Schweizer SGS 2-33A, registration N65901, at Mattoon, IL.

What was the probable cause of the accident?

The glider instructor's premature release of the tow line due to a misperception of the tow plane's performance, compounded by the speed brakes and spoilers being fully deployed during the takeoff run.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001213X34132. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.

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