It was a Saturday in June, in the middle of the afternoon, a clear day, in open country-a most perilous time and place. Three sport airplanes-a Pitts S-1, an Acro Sport and an RV-6-were on their way from an airshow at the Longmont Airport, on the north side of Denver, to Centennial Airport at Englewood, on the south side. Longmont and Centennial are only 30 nm apart as the crow flies, but the crow doesn't know about Class B airspace. Denver International lies between the two airports, and so to get from one to the other requires a knight's move to the west around the Denver TCA. Several complications dot this route; the first is the Boulder Airport, an uncontrolled field with considerable soaring activity, located about eight nautical miles south of Longmont.
The three airplanes left Longmont at about 2:45. The two biplanes flew together in echelon formation, while the RV-6, a two-seat tandem low-wing homebuilt occupied by its owner-builder and a passenger, trailed a little distance behind them. At about the same time a Burkhart Grob G103C Twin III Acro was airborne, in spite of being encumbered with the longest name ever given an airplane, near Boulder. The Grob is a two-seat tandem sailplane with a 60-foot wingspan.
The passenger in the Grob felt airsick, and the airplane was returning to land at Boulder. Runway 8 was active. They were approaching the airport from the south at 6,100 feet msl, about 800 feet above the surface, when the pilot, who was in the rear seat, observed a two-plane formation passing in the opposite direction off his right wing. He wondered why they were crossing the airport at pattern altitude. A moment later his passenger yelled that an airplane was directly in front of them. It was the RV-6.
The pilot raked the Grob over into a steep left bank, at the same time deploying the airbrakes. The right wingtip of the sailplane struck the propeller, lower cowling and right main wheel of the RV-6. Eighteen inches of the Grob's wing was sheared off, and the RV lost one propeller blade and its lower cowling.
The Grob, which was relatively lightly damaged, continued its left turn onto the downwind leg and landed safely on the glider runway, which is parallel to, and just to the north of, the one for powered aircraft. The RV turned sharply to the right and flew northwestward. Its pilot made a distress call on the unicom frequency. He then banked steeply to the left. According to witnesses, the airplane appeared to stall. It rolled inverted and crashed into a lake near the runway threshold.
