In a retreating-blade stall, however, only the retreating half of the helicopter's rotor disc experiences a stall. The advancing blade continues to generate lift, but the retreating blade enters a stall condition, usually resulting in an uncommanded increase in pitch of the nose and a roll in the direction of the retreating side of the rotor disc. In counter-clockwise rotating rotor systems (as in most American-made types) this is the left side. In clockwise rotating systems it is a roll to the right.