This paper presents a new approach to the problem of handling a vehicle under emergency conditions, showing that the parameter plane method gives a clearer insight into the handling characteristics of vehicles under emergency braking conditions. The value of this method lies in the selection of the two independent parameters. For the particular problem considered, cornering stiffness at the front wheel may be taken as one independent parameter and cornering stiffness at the rear wheel is taken as the other. In other problems, suitable choice of the parameters may be made in order to obtain the necessary information. An illustrative example is included.The effect of wheel locking on the handling characteristics of the vehicle is studied; the degree of instability is redefined as a nondimensional number, and its utility is indicated. If a specified degree of stability is to be achieved, the roots of the characteristic equation of the system must lie within specified boundaries of the complex s-plane. These boundaries may be mapped on the parameter plane. An adaptive brake control system may be designed to confine the movement of the operating point to the region thus specified.