Aviation Accident Summaries

Aviation Accident Summary SEA01LA153

Enumclaw, WA, USA

Aircraft #1

N82AS

LET Blanik L-13

Analysis

The glider pilot reported that the towline prematurely released from the tow plane (Piper PA-18). He reported that this occurred shortly after takeoff from runway 28, about 200 feet above ground level (AGL). After the unscheduled disconnect, the glider pilot initiated a turn to the right in an effort to reach the departure runway. He reported that during the turn, the glider "pitched down" and did not respond to control inputs. Shortly thereafter, the glider impacted trees and terrain. This was the second failed attempt to launch the glider; the first attempt resulted in an unscheduled release immediately following the initiation of the tow. Following the first unscheduled release, the "Field Manager" reconnected to towline to the PA-18, and the second tow was initiated. In both cases, the towline prematurely released from the release hook on the tow aircraft, but remained attached to the latching mechanism on the glider. The handle for the tow-hitch is located on the floorboard of the tow plane's forward cockpit. To open the hitch, the handle is moved from the forward position to the aft position. According to the tow plane pilot, the handle had not been actuated and was in the forward position when the unscheduled releases occurred. Postaccident examination and testing of the tow-hitch revealed no discrepancies or anomalies that would explain the unscheduled release. In a written statement, the glider pilot indicated that he had not been briefed on potential emergency landing sites near the departure field. Additionally, he stated that had he been briefed, he would have "...made the decision to fly to such a site given my altitude at release." The elevation at Bergseth Field is approximately 1,100 feet mean sea level (MSL). Runway 10/28 is a 2,100 by 60 foot turf runway, with rising terrain to the east and sloping terrain to the west The terrain to the west slopes down to an elevation of approximately 500 feet MSL.

Factual Information

On August 19, 2001, about 1235 Pacific daylight time, a LET Blanik L-13 glider, N82AS, sustained substantial damage during a forced landing at a private airstrip near Enumclaw, Washington. The glider is registered to Puget Sound Soaring Association, Kent, Washington, and was being operated as a visual flight rules (VFR) personal/pleasure flight under the provisions of Title 14, CFR Part 91. The private pilot sustained minor injuries and his passenger sustained serious injuries. Visual meteorological conditions prevailed, and no flight plan was filed for the local flight. The flight originated from Bergseth Field shortly before the accident. In a written statement dated September 4, 2001, the pilot of the glider reported that the towline prematurely released from the tow plane (Piper PA-18). The report indicated this occurred shortly after takeoff from runway 28, about 200 feet above ground level (AGL). After the unscheduled disconnect, the pilot initiated a turn to the right in an effort to reach the departure runway. He reported that during the turn, the glider "pitched down" and did not respond to control inputs. Shortly thereafter, the glider impacted trees and terrain. In his written statement, the pilot indicated that he had not been briefed on potential emergency landing sites near the departure field. Additionally, he stated that had he been briefed, he would have "...made the decision to fly to such a site given my altitude at release." This was the second failed attempt to launch the glider; the first attempt resulted in an unscheduled release immediately following the initiation of the tow. Following the first unscheduled release, the "Field Manager" reconnected the towline to the PA-18, and the second tow was initiated. In both cases, the towline prematurely disconnected from the release hook on the tow aircraft, but remained attached to the latching mechanism on the glider. The elevation at Bergseth Field is approximately 1,100 feet mean sea level (MSL). Runway 10/28 is a 2,100 by 60 foot turf runway, with rising terrain to the east and sloping terrain to the west. The terrain to the west slopes down to an elevation of approximately 500 feet MSL. The handle for the release hook is located on the floorboard of the tow plane's forward cockpit. To open the tow-hitch, the handle is moved from the forward position to the aft position. According to the tow plane pilot, the handle had not been actuated and was in the forward position when the unscheduled releases occurred. A review of the maintenance records indicated that the Schweizer Aircraft tow-hitch was installed on the tow airplane on September 4, 1999. A representative from the Puget Sound Soaring Association reported that between September 12, 1999, and September 19, 2001, approximately 705 tow cycles were completed without previous incidents. Postaccident examination and testing of the tow-hitch revealed no discrepancies or anomalies that would explain the unscheduled release.

Probable Cause and Findings

The premature release of the towline and the pilot's improper selection of a landing area following the release. Factors include improper preflight planning.

 

Source: NTSB Aviation Accident Database

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