The aircraft was conducting cattle spotting operations from an estimated height of between 90 and 150 metres above ground level. The pilot was relatively new to the task and was being guided by the passenger, who was in radio contact with the ground mustering party. The procedure was for the aircraft to spot and then fly directly over cattle as a guide to the ground party. Following the first flight of the day, the aircraft was refuelled from a newly opened 200 litre drum of aviation gasoline. The aircraft then took off normally and flew over one group of cattle before heading north-east towards another area. A short time later, a high revving engine noise was heard followed immediately by the sound of impact. The aircraft had impacted the ground 48 degrees nose down and slightly right wing low on a heading of 158 degrees Magnetic. The fuel tanks ruptured on impact and the wreckage caught fire. The extent of the fire damage was such that a thorough examination of the wreckage was not possible. However, of the components that were able to be checked, no fault was found which might have prevented normal operation of the aircraft. The engine was operating at impact and the flaps were at 15 degrees. The steep nose down attitude of the aircraft at impact is typical of what might be expected as a result of the aircraft stalling at low level and the pilot having insufficient height to effect recovery. While there is no proof of this occurring, there were circumstances existing which could have contributed to its development. These included the sun being on a Magnetic bearing of 40 degrees and an elevation of 25 degrees above the horizon at the time of the accident, indicating that the the pilot could have been affected by sun glare as the aircraft headed north-east. During the refuelling stop, the passenger remarked on the turbulent conditions at the operating height of the aircraft. If the aircraft was operating at comparatively low speed (and the flap setting probably indicates this), then the turbulent conditions could have upset the aircraft to the extent that it stalled, with the sunglare preventing the pilot detecting the upset. FACTOR The following factor was considered relevant to the development of the accident For reason(s) which could not be positively established, the pilot lost control of the aircraft at a height from which recovery to normal flight could not be effected.