Sequence of Events
A Cessna 150, registration N1766Q, was ahead of a Stearman, registration N89X, in a left traffic pattern at an uncontrolled airport. The Cessna pilot was heard making a call on downwind. The Stearman pilot reported observing traffic on downwind but then lost sight of it. When the Stearman pilot called on downwind, the Cessna was observed to be on base. Subsequently, the Stearman pilot was heard calling on base with traffic not in sight.
A witness observed both aircraft on final approach. The Stearman and the Cessna collided, with the Stearman positioned above the Cessna at the moment of impact. The collision caused the right aileron to separate from the Cessna, after which the aircraft descended to the ground. The Stearman pilot was able to continue the flight and landed at the airport.
Traffic Pattern Procedures
According to the Airman's Information Manual (AIM), at uncontrolled airports, traffic calls should be made on downwind, base, and final. Additionally, the AIM advises pilots to monitor the frequency and exchange traffic information.