Circumstances:
The pilot reported that he had obtained permission to use the Authorised Landing Area and had operated there on several occasions. He was assured that the strip was maintained and mown regularly. On arrival the previous day, he noted that the grass was unusually long. From the take-off weight chart, he calculated that in nil wind conditions the aircraft weight was less than the maximum allowable for the prevailing strip conditions. Several taxying runs were made up and down the strip to assess aircraft acceleration. The pilot then commenced a take-off run towards the west into an estimated five to eight knot headwind. Take-off safety speed was achieved, and the aircraft became airborne about sixty metres before the end of the strip but failed to climb. The airspeed began to decay, and the aural stall warning was heard. The pilot closed the throttle and landed in a paddock ahead. Because of the damp grass, braking was ineffective, and the aircraft collided with a fence. Although the strip elevation was 3350 feet, the pilot said that based on earlier advice from his instructors, and from his knowledge of the engine manufacturers recommendations, he did not consider leaning the fuel mixture for take-off. He also said that local pilots had suggested there was a wind tunnelling effect at the end of the strip due to the terrain.
