What aircraft was involved and where did it happen?

The accident on 1996-05-31 involved a aircraft, at FI.

What was the probable cause of the accident?

The accident was caused by the pilot's failure to execute a standard landing approach, specifically through the misjudgment of altitude and distance, combined with the improper use of flaps and airbrakes and a failure to compensate for crosswind conditions.

Glider Crash in Nastola Caused by Improper Landing Approach

A Schleicher ASH 25 glider sustained heavy damage after the pilot misjudged altitude and distance during an improvised landing in a forest near Vuolenkoski.

What happened

On May 31, 1996, a Schleicher ASH 25 glider, registration BGA 4026, was participating in a training flight for the European Championship distance task. After approximately five hours of flight, the pilot determined that insufficient lift was available to return to Räyskälä and decided to divert to the nearest airfield, Vesivehmaa.

Upon approaching the area, the pilot found that lift had ceased and decided to perform a field landing in a nearby area. The pilot initiated a landing pattern at an unusually low altitude of approximately 400 feet. During the final stages of the approach, the pilot deployed the landing flaps into the landing position, which significantly increased the sink rate. While attempting to correct the flight path and manage the descent, the pilot encountered a crosswind that drifted the aircraft off course.

In an attempt to stabilize the aircraft, the pilot retracted the flaps to a thermalling setting, but the sudden change in configuration, combined with the low altitude, led to a high sink rate. The aircraft entered a state of partial stall while in level flight. The glider struck the tops of several 20-meter-tall spruce trees before coming to a rest in a dense forest at an altitude of approximately 13 meters. The passenger sustained bruises to the back and knees, but no fatalities occurred.

The investigation

The investigation focused on the pilot's approach maneuvers, the configuration of the aircraft's flaps and airbrakes, and the environmental conditions at the landing site. Investigators examined the pilot's experience, noting that while the pilot had significant total glider experience, this was his first field landing in this specific aircraft type. The investigation also reviewed the aircraft's flight manual regarding flap settings and the impact of sink rates at various speeds.

Findings

The pilot did not execute a standard landing pattern, instead performing several 360-degree turns at an extremely low altitude.
The pilot misjudged both the altitude and the distance to the selected landing field.
The improper use of landing flaps and airbrakes contributed to an excessive sink rate.
The pilot failed to adequately account for the effects of the crosswind during the final approach.
The pilot's lack of experience with field landings in the Schleicher ASH 25 was a contributing factor.
The terrain, characterized by surrounding hills, complicated the approach.