A formation in which the defensive backs crowd the line of scrimmage, creating the appearance of 6 linebackers. The defence got its name from the "46" jersey number of Chicago Bears safety Doug Plank, who was a starter when Bears defensive coordinator Buddy Ryan developed the defence in the first half of the 1980s. It is also known as the "Bear" defence because Ryan popularised it with the Bears, and took it with him to future NFL head coaching positions.