The operation was to spray a sorghum crop in an approximately rectangular field aligned north-east/south-west. There were four isolated trees in the field and a single wire power line was located 80 feet outside and parallel to the north-east boundary. The wire was supported between two poles 890 feet apart and the height of the wire varied between 34 feet above the ground at the pole adjacent to the northern corner of the field and about 24 feet at the centre of the span. The field contained two crops of different ages on alternating contour strips and, as only the younger crop was to be sprayed, it was necessary for the pilot to turn the spray on and off four times on each run along the field which was approximately 3000 feet in length. Because of the curved contours the positions along each run at which the spray control was operated would vary. During the day there were four telephone contacts concerning the proposed operation between representatives of the operator and the farmer or his representative but the farmer did not have the opportunity to speak directly to the pilot and thus brief him regarding the power line. The pilot had not previously treated this particular field but he had operated over adjacent fields and properties. The farmer and a neighbour acted as markers and when the aircraft arrived overhead they moved into positions at either end of the field. The pilot made a brief aerial inspection and commenced operations running north-east and south-west alternately. On each of the first three runs in each direction the aircraft passed under the power line and the circumstances suggest that the pilot was aware of its presence. The seventh run was made towards the north-east and, at its completion, the aircraft commenced to pull in the vicinity of the boundary fence which was earlier than on previous runs. The aircraft then struck the power wire in a nose up, port wing down attitude. The wire became caught on a flood light which was mounted on the underside of the port wing. The aircraft veered sharply to the left before the wire wrenched out the light and the internal wing drag strut assembly on which the light was mounted. The aircraft continued rolling to the left as it climbed to a height of about 50 feet and it then dived into the ground in an inverted steep nose down attitude and burst into flames.