On June 24, 1999, approximately 1230 mountain daylight time, a Cessna A188B, N4788Q, collided with a power line during a CFR Part 137 aerial application flight about 25 miles south of Big Sandy, Montana. The commercial pilot received minor injuries, and the aircraft, which was owned and operated by Big Sandy Spraying Service, sustained substantial damage. The aircraft, which was being operated in visual meteorological conditions, had been airborne for about 20 minutes. No flight plan had been filed, and there was no report of an ELT activation. According to local authorities, and the pilot's written statement, the pilot was pulling up from the end of an application run when the aircraft flew into the wire. The pilot said that he knew the aircraft was approaching the wire, but just as he initiated his pull-up to clear it, the aircraft encountered a downdraft. He was unable to overcome the effects of the downdraft in time to avoid contact with the wire.