Unintended car movement is uncontrolled travel of the car away from a landing with the doors open, caused for example by brake failure or a rope or traction loss. Since EN 81-20 every lift must have a UCM protection means that detects the movement and stops the car within defined distances, typically before the door sill gap exceeds safe limits. The protection is usually realised by a rope brake, a second safety gear or brake monitoring on the traction machine, and must be type-examined.