Flight Crew Commercial; Flight Crew Instrument
Flight Crew Last 90 Days 51.2; Flight Crew Total 355; Flight Crew Type 30
Communication Breakdown; Situational Awareness; Training / Qualification
Conflict NMAC; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Took Evasive Action
Human Factors
Our aircraft had just landed at ZZZ when a single-seat aerobatic biplane began to do low-level aerobatics (hammerheads and rolls) opposite normal traffic in the pattern. A Cessna 150 entered left downwind Runway XX; well spaced from the biplane; which was in a modified right downwind/base; when the biplane crossed the field and entered a midfield left crosswind-to-downwind behind the 150. The 150 continued downwind; turned base then final; when the biplane banked hard from downwind directly to final abeam the 150 and approximately 25 feet above. The 150 initiated a go-around and the biplane did the same; nearly colliding which each other. The 150 eventually landed on a second go-around while the biplane continued to execute high speed low passes over the runway at about 50 feet AGL. The problem likely arose because the biplane; which was NORDO; was engaged in a low level acrobatics display for a group of onlookers in the tiedown area and was not scanning for conflicting traffic. The 150 likely saw the biplane traffic near the airport; but the biplane's erratic behavior and rapid altitude and direction changes would have complicated efforts to maintain separation. The conflict could have been resolved if the biplane pilot refrained from low-level aerobatics in the vicinity of the traffic pattern; was visually scanning for traffic; and vacated the traffic pattern area when other traffic was inbound to land.
Pilot observer reported a near mid air collision between two airplanes in airport traffic pattern.