On September 11, 1993, at 0925 Pacific daylight time, a Culver LFA, N41729, operated by William Lawson, collided with a banner pickup line which had been strung across the northern portion of runway 16/34 at the Sonoma Valley, California, uncontrolled airport. The collision occurred as the airplane was taking off from runway 34. Visual meteorological conditions prevailed and no flight plan was filed. The airplane was substantially damaged. The private pilot and passenger received serious injuries. The flight was originating at the time of the mishap. The pilot reported that prior to his takeoff roll he did not observe any obstructions on the runway. The pilot stated that seconds before impact he observed the obstacle and attempted to avoid it by abruptly pulling up. The airplane's landing gear snagged the pick up wire, and the plane crashed into an adjacent open field. A witness reported that the banner pickup equipment had been placed across the north end of runway 34. The equipment consisted of, in part, two ten-foot tall poles which were marked with two flags and orange cones. The equipment was positioned on both sides of the runway. The operator of the banner tow company reported that prior to the accident he had a meeting with the airport manager and was told he could set up his tow equipment on runway 16/34. The operator also reported that runway 16/34 was marked with an "R." He said since he observed airplanes using runway 7/25, he believed runway 16/34 was not active. The banner operator further reported that he had been issued a FAA waiver permitting banner operations. Item number 17 on the waiver required, in pertinent part, that his banner pickup and drop area should be located at least 500 feet from any active runway, person, building, parked automobiles, and aircraft. The accident pilot reported that he based his airplane at the airport, and he was familiar with the use of all runways. The pilot had previously received permission to use the restricted runway.