On July 1, 1997, at 1715 hours Pacific daylight time, an Aviat Aircraft A-1 Husky, N13HU, veered off the right side of runway 31 while landing at Gnoss Field, Novato, California. The aircraft encountered a drainage ditch and subsequently nosed over. Visual meteorological conditions prevailed at the time and included winds from 210 degrees at 15 knots. The aircraft sustained substantial damage. The private pilot and one passenger were not injured. The flight originated at Logan, Utah, on the day of the accident at 1345 mountain standard time as a personal cross-country flight to Novato. The pilot did not respond to requests from the Safety Board for information regarding this accident. In a report to his insurance company, the pilot stated that he was landing on runway 31 and encountered a crosswind gust. The aircraft then veered off the right side of the runway and ran into a drainage ditch as the pilot had slowed to nearly a stop. When the aircraft contacted the bottom of the ditch, it nosed over onto its back. Federal Aviation Administration inspectors from the Oakland, California, Flight Standards District Office examined the aircraft, the runway, and the drainage canal. The aircraft sustained damage to both wing spars and the vertical stabilizer. No mechanical discrepancies were observed by the inspectors. Examination of runway 31 revealed two parallel 30-foot-long skid marks which began near the right side of the runway at 1,934 feet from the approach end. A right side only skid mark about 30 feet long and near the right side of the pavement was observed starting at 2,003 feet from the runway end. Two additional right side only skid marks were observed starting at 2,038 and 2,083 feet, respectively. At a distance of 2,110 feet, the tire tracks departed the right side of the runway and continued 120 feet until terminating at the drainage ditch. The 25-foot-wide by 6-foot-deep drainage canal parallels the runway and is 45 feet from the runway edge.