Both pattern and IMAC involve flying aerobatics, the schedules and type of model required to fly at a top level are quite different. Pattern requires models of less than 2 meters wingspan and length, weighing less than 5kg. These typically do not look like full size aircraft, with the designs optimized over the years to perform the maneuvers required with great precision. IMAC on the other hand is best flown with a larger model, which must resemble a full size aerobatic aircraft – except for basic (the introductory class) where any model goes!