NTSB Identification: CEN09CA269
14 CFR Part 91: General Aviation
Accident occurred Sunday, April 26, 2009 in Adrian, MI
Probable Cause Approval Date: 07/14/2009
Aircraft: LET L-23 Super Blanik, registration: N238SB
Injuries: 2 Uninjured.

NTSB investigators used data provided by various entities, including, but not limited to, the Federal Aviation Administration and/or the operator and did not travel in support of this investigation to prepare this aircraft accident report.

Before the accident flight, the glider flight instructor observed adverse weather approaching the airport from the south. He wanted to demonstrate a crosswind landing to his student before ceasing glider operations due to the adverse weather. The glider released from the tow airplane around 1,000 feet above ground level and then proceeded on downwind for runway 29. While on final approach, the flight instructor had difficulty maintaining proper runway alignment due to a strong, gusting crosswind. As a result, he elected to land the glider in a grassy area immediately north of the runway. He noted that his forward visibility was limited by heavy rain. The glider impacted a taxiway sign during the landing, substantially damaging the left wing. Weather radar and surface observations indicated that the airport was affected by a thunderstorm shortly after the glider departed on the local area flight. The thunderstorm produced heavy rain, lightning, and strong winds. During the accident flight, the airport's automated surface observing system recorded a peak wind from 220 degrees magnetic at 42 knots. The glider's maximum demonstrated crosswind component for safe approach, landing and aerotow launching was 16 knots.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

The flight instructor's inadequate compensation for the strong, gusting crosswind during landing. Contributing to the accident was the flight instructor's decision to attempt flight with known adverse weather approaching the airport.

Full narrative available

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