NTSB Identification: WPR10FA068A
14 CFR Part 91: General Aviation
Accident occurred Saturday, November 28, 2009 in Middletown, CA
Probable Cause Approval Date: 12/20/2010
Aircraft: SCHLEICHER ASW-27, registration: N127AL
Injuries: 2 Fatal.
NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.
The airplane departed the airport with the glider in tow. Gusting crosswind conditions existed at the time of the takeoff and witnesses reported that the glider appeared to be encountering turbulence during the climb out. The glider released from the tow plane a short time later, maneuvered in the vicinity of the release, and then simultaneously returned to the airport at the same time as the airplane. Both aircraft entered downwind legs on each side of the same runway, with the glider on the right downwind and the airplane on the left downwind. They continued on downwind, and turned onto their respective base legs about the same time. As both aircraft turned onto final, they collided. Paint transfer marks, Global Positioning System (GPS) flight track data, and a photograph taken just after the collision indicated that the airplane's right wing and right main landing gear struck the empennage of the glider just aft of the cabin. The glider's flight track back to the airport, and the use of the right-hand traffic pattern likely indicated that the pilot encountered unfavorable weather conditions that necessitated use of the non-standard pattern. Additionally, GPS flight track data indicated that the glider overshot the runway centerline during the turn from base to final, indicative of him encountering a crosswind. The airplane was not equipped with a radio transceiver, and the left-hand traffic pattern was considered standard for the private airstrip. The seating positions of both pilots, and the relative distance between the aircraft would have given both pilots an unobstructed view of the opposing aircraft during the downwind and base legs of the arrival. 14 CFR 91.113(d)(2) and (3)(e) specifies general right of way rules and rules for traffic pattern operations. In part, a glider has the right-of-way over an airship, powered parachute, weight-shift-control aircraft, airplane, or rotorcraft. For traffic pattern operations when aircraft are approaching each other head-on, or nearly so, each pilot of each aircraft shall alter course to the right.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The failure of both pilots to see and avoid the other airplane. Contributing to the accident was the pilot flying a non-standard approach to the private airstrip. Full narrative available
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