Occurrence
At approximately 1617 central standard time on the day of the accident, three United States-registered biplanes were performing a simulated dogfight display at Moose Jaw/Air Vice Marshal C.M. McEwen Airport as part of the Saskatchewan Air Show. The display team, The Masters of Disaster, consisted of a Waco UPF-7 (registration N2369Q), a Wolf-Samson (registration N985PW), and a Pitts Special (registration N99MF). A ground display featuring a jet-powered truck called Shockwave was also part of the act.
During the performance, the three biplanes were executing a series of crosses and chases. As the jet-powered truck moved into position on the 500-foot show line, the biplanes entered a maneuver in preparation for crosses centered on the truck. The Waco and the Wolf-Samson collided near show center at approximately the 1500-foot show line. Both biplanes caught fire and crashed between the 1500-foot show line and the outer runway. Both pilots were killed at impact, and both aircraft were destroyed. Debris fell away from the crowd toward the outer runway. Immediate implementation of emergency procedures kept spectators from moving toward the burning wreckage.
Display Team
The Masters of Disaster display team was formed in 2002. The display featured three biplanes performing simulated air combat maneuvers, or dogfights, with crosses that created the illusion of near collisions. The jet-powered truck was chased by the biplanes as it maneuvered on the ground. The crosses were planned to ensure safe separation through visual contact and an agreed set of rules called a "contract," which established how each pilot would fly the maneuver and who was responsible for visual separation, as well as how to disengage if the maneuver did not go as planned.
Aircraft
The Waco UPF-7 (N2369Q) was originally manufactured in 1940 and had been extensively modified and strengthened for displays. It was powered by a Pratt & Whitney R-985 and a General Electric J-85 jet engine mounted underneath the fuselage, with the cockpit moved aft. The Wolf-Samson (N985PW) was a replica of an original Wolf-Samson biplane, registered in 1993, powered by a Pratt & Whitney R-985 engine.
Maneuver
The maneuver being executed was a modified version of the "Dairy Turn." The original Dairy Turn had not caused problems because the Waco turned between the Wolf-Samson and the spectators, resulting in non-crossing flight paths and visual contact. The modified version resulted in flight paths that crossed twice, creating two points of possible collision. The first crossing was more dangerous because the tracks intersected at 90°, with both aircraft potentially banked away from each other. Timing was critical, requiring visual contact. The modified maneuver did not ensure safe execution unless at least one pilot had visual contact. Due to increased risk, the pilots should have ensured a clearly understood contract was in place.
Pilot Actions
The Wolf-Samson pilot initiated a climb that was not part of the planned maneuver. The climb was consistent with the pilot concluding that the Waco was late and that there was an imminent risk of collision. His action would have allowed the Waco to pass ahead and below, establishing altitude separation if his contract was to maintain separation, but it did not positively regain visual contact. The Waco pilot also climbed, consistent with concluding lateness created imminent risk. His subsequent left turn was consistent with trying to fly away from the potential collision. Both pilots' actions negated each other, and neither regained visual contact.
Weather and Radios
The wind blew smoke from the display away from the performers, providing a clear view of the airspace. However, the wind may have blown the Wolf-Samson during its turn, possibly causing the pilot to hold bank angle longer and increasing the period without visual contact. Although open cockpits interfered with radio intelligibility, a radio call might have ensured only one pilot climbed to achieve separation.
Public Safety
Immediate public address announcements by the air show commentator likely kept spectators from moving toward the crash site, increasing public safety. The debris field length indicated sufficient energy for debris to reach the spectator area if directed toward the show line. The Dairy Turn was not described in the sequential list provided to Transport Canada, preventing proper evaluation of energy management. The limited information for other maneuvers also precluded energy management assessment. The display was not used in annual SAC renewals, and no Transport Canada representative was present at the air show.
Findings
The Transportation Safety Board's investigation identified that the Dairy Turn maneuver had been modified such that a temporary loss of visual contact could occur immediately before the aircraft crossed flight paths. This made timing critical and added two potential points of collision. The maneuvers immediately before the collision indicated that the performers had not established a clearly understood contract for the revised maneuver, and the actions of each performer negated the actions of the other, with neither taking positive action to regain visual contact. Additionally, the timing of the maneuver was lost when the Waco turned late at show centre. The sequential maneuver information provided to Transport Canada was not detailed enough to allow a thorough review of energy management.