On September 30, 1999, approximately 1130 mountain daylight time, a Piper PA-18-150, N3799Z, was substantially damaged when it collided with terrain during landing roll at Telluride Regional Airport, Telluride, Colorado. The private pilot and one passenger were not injured. Visual meteorological conditions prevailed, and no flight plan had been filed for the personal cross-country flight being conducted under Title 14 CFR Part 91. The aircraft departed Montrose Regional Airport, Montrose, Colorado, at 1100. According to the pilot, prior to takeoff from Montrose, he called Telluride airport and asked an airport employee what the weather conditions were. He was told that the wind was calm. Prior to entering the traffic pattern for landing at Telluride, he listened to the airport's Automated Surface Observation System (ASOS), and again the wind was reported as calm. He then confirmed that with the airport's windsock. The Federal Aviation Administration's Airport/Facility Directory (Southwest U.S.) states that all takeoffs at Telluride are recommended to be conducted on runway 27, and all landings should be performed on runway 09 to avoid populated areas. The pilot stated that touchdown and initial rollout on runway 09 were "normal." However, after the tail was lowered onto the runway, the aircraft encountered a tailwind gust and ground looped. The airplane sustained damage to the right wing and right landing gear. When the pilot exited the aircraft, he noted that the winds were out of the west. There is no manual weather observation facility at Telluride airport. The closest weather facility is located at Montrose, located 33.3 nm to the north. At 1053, the winds at Montrose were reported from 290 degrees at 6 knots. The next weather record was at 1353, with winds variable at 4 knots.