Accident Overview
Two identically painted American Champion 8KCAB airplanes, registration numbers N561ER and N562ER, collided in flight while performing a formation aerobatic hammerhead maneuver. The airport at which the accident occurred was hosting an airshow where the accident pilots were scheduled to perform a formation aerobatic routine.
Witness Observations
Witnesses reported observing the two airplanes practicing the routine on several different occasions during the previous months and had become familiar with it. According to witnesses, during the accident maneuver, a vertical climb was initiated with both airplanes side-by-side. At the apex of the maneuver, one or both airplanes moved out of their normal positions, resulting in them becoming stacked one on top of the other. Following the initial contact, witnesses observed several additional contacts as the airplanes fell to the ground.
Damage and Contact Evidence
Examination of the wreckage revealed color transfers, damage patterns, and witness marks indicating that the propeller of N561ER made multiple contacts with the engine compartment and cockpit of N562ER. Additionally, contact between the left lift strut of N562ER and the empennage of N561ER damaged and separated the vertical and horizontal stabilizers of N561ER.
Mechanical Examination
An airframe and engine examination of both airplanes revealed no mechanical discrepancies that would have precluded normal operation and control. No pre-existing faults were identified that could have contributed to the collision.