On March 5, 1989, a Cessna 170B (registration N2766C) was involved in an aviation accident near Casa Grande, AZ. Investigators recorded the probable cause as: The collision between the experimental acrobatic biplane and the normal category airplane during formation flight maneuvers. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
An experimental acrobatic biplane overtook a Cessna during cruise flight and collided with it while maneuvering inverted, resulting in damage to both aircraft.
What happened
A private pilot operating an experimental category acrobatic biplane, N64WD, intended to conduct formation flying with a commercial pilot who was piloting a normal category aircraft, N2766C. Both pilots had equipped their respective aircraft with radio communication gear to facilitate coordination during the flight.
During the operation, the Cessna was established in cruise flight. The biplane approached from behind and successfully overtook the Cessna. Once alongside or slightly ahead, the pilot of the biplane initiated an inverted maneuver. During this phase of the flight, the two aircraft collided.
Probable cause
The collision between the experimental acrobatic biplane and the normal category airplane during formation flight maneuvers.