Narrative:

At approximately Y:00 pm on 6/mon/91, we impacted the ground at a high rate of descent in a left skid at fantasy haven airport, tehachapi, ca. The CFI was the PIC and was flying from the rear seat. The student pilot was flying from the front seat. This instructional flight departed normally at approximately Y:00 pm with an aeronautical tow to 2000' AGL. The student pilot handled the controls throughout the first part of the flight as he flew in the shear-line to maintain altitude. As the lift started to diminish, he arrived about one mi west of the initial point of entry established by the fixed base operator for entering the glider pattern. The CFI told him to turn toward the initial point of entry, as he was getting too low. As the aircraft proceeded toward the initial point of entry, the CFI noticed a sudden increase in sink rate, with the variometer showing 1000 FPM down. The CFI told the student pilot that he was taking control because the aircraft was getting into a dangerous situation due the high rate of sink. The CFI flew the aircraft directly onto a close, right downwind leg. The variometer remained at 1000 FPM down on the downwind leg. At just above 200' AGL, the CFI initiated a tight 180 degree turn to the right for final approach to the runway. It quickly became apparent that the turn could not be completed in time due to the continued rapid rate of descent. Just above the surface the CFI leveled the aircraft and slowed the approach speed from an estimated 55 mph to an estimated 45 mph. The glider landed hard on the main wheel in a left skid. Additional parameters: the WX was clear, visibility estimated at 40 mi and the surface wind was approximately 270 degrees magnetic at 15 KTS. The runway in use was 27R. The T/D site was level dirt west/O obstructions within the airport boundary. The spoilers were retracted throughout the evolution. The glider had been assembled with the CFI's help earlier in the day, and given a thorough preflight inspection by him with no discrepancies noted. The CFI had flown the glider on several other flts that day, and had encountered no problems with the aircraft. Causes: high sink due to meteorological conditions; pilot's failure to take best corrective action. Prevention: should have chosen an off field landing instead of trying to make it to the runway in a high sink rate condition. Did not qualify as accident or incident under NTSB 830.

Google
 

Original NASA ASRS Text

Title: OFF ARPT LNDG MADE IN SAILPLANE ACTIVITY TRAINING FLT WHEN HIGH SINK RATE IS OBSERVED AND UNCONTROLLED.

Narrative: AT APPROX Y:00 PM ON 6/MON/91, WE IMPACTED THE GND AT A HIGH RATE OF DSNT IN A L SKID AT FANTASY HAVEN ARPT, TEHACHAPI, CA. THE CFI WAS THE PIC AND WAS FLYING FROM THE REAR SEAT. THE STUDENT PLT WAS FLYING FROM THE FRONT SEAT. THIS INSTRUCTIONAL FLT DEPARTED NORMALLY AT APPROX Y:00 PM WITH AN AERO TOW TO 2000' AGL. THE STUDENT PLT HANDLED THE CTLS THROUGHOUT THE FIRST PART OF THE FLT AS HE FLEW IN THE SHEAR-LINE TO MAINTAIN ALT. AS THE LIFT STARTED TO DIMINISH, HE ARRIVED ABOUT ONE MI W OF THE INITIAL POINT OF ENTRY ESTABLISHED BY THE FIXED BASE OPERATOR FOR ENTERING THE GLIDER PATTERN. THE CFI TOLD HIM TO TURN TOWARD THE INITIAL POINT OF ENTRY, AS HE WAS GETTING TOO LOW. AS THE ACFT PROCEEDED TOWARD THE INITIAL POINT OF ENTRY, THE CFI NOTICED A SUDDEN INCREASE IN SINK RATE, WITH THE VARIOMETER SHOWING 1000 FPM DOWN. THE CFI TOLD THE STUDENT PLT THAT HE WAS TAKING CTL BECAUSE THE ACFT WAS GETTING INTO A DANGEROUS SITUATION DUE THE HIGH RATE OF SINK. THE CFI FLEW THE ACFT DIRECTLY ONTO A CLOSE, R DOWNWIND LEG. THE VARIOMETER REMAINED AT 1000 FPM DOWN ON THE DOWNWIND LEG. AT JUST ABOVE 200' AGL, THE CFI INITIATED A TIGHT 180 DEG TURN TO THE R FOR FINAL APCH TO THE RWY. IT QUICKLY BECAME APPARENT THAT THE TURN COULD NOT BE COMPLETED IN TIME DUE TO THE CONTINUED RAPID RATE OF DSNT. JUST ABOVE THE SURFACE THE CFI LEVELED THE ACFT AND SLOWED THE APCH SPD FROM AN ESTIMATED 55 MPH TO AN ESTIMATED 45 MPH. THE GLIDER LANDED HARD ON THE MAIN WHEEL IN A L SKID. ADDITIONAL PARAMETERS: THE WX WAS CLR, VISIBILITY ESTIMATED AT 40 MI AND THE SURFACE WIND WAS APPROX 270 DEGS MAGNETIC AT 15 KTS. THE RWY IN USE WAS 27R. THE T/D SITE WAS LEVEL DIRT W/O OBSTRUCTIONS WITHIN THE ARPT BOUNDARY. THE SPOILERS WERE RETRACTED THROUGHOUT THE EVOLUTION. THE GLIDER HAD BEEN ASSEMBLED WITH THE CFI'S HELP EARLIER IN THE DAY, AND GIVEN A THOROUGH PREFLT INSPECTION BY HIM WITH NO DISCREPANCIES NOTED. THE CFI HAD FLOWN THE GLIDER ON SEVERAL OTHER FLTS THAT DAY, AND HAD ENCOUNTERED NO PROBS WITH THE ACFT. CAUSES: HIGH SINK DUE TO METEOROLOGICAL CONDITIONS; PLT'S FAILURE TO TAKE BEST CORRECTIVE ACTION. PREVENTION: SHOULD HAVE CHOSEN AN OFF FIELD LNDG INSTEAD OF TRYING TO MAKE IT TO THE RWY IN A HIGH SINK RATE CONDITION. DID NOT QUALIFY AS ACCIDENT OR INCIDENT UNDER NTSB 830.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.