Available transfer capability (ATC) quantifies the viable increase in real power transfer from one point to another in a power system. ATC calculation has predominantly focused on steady-state viability. Point-to-point transfer can be increased until equilibrium point quantities, given by a power flow, reach security limits. Generally the equilibria are evaluated for a number of contingencies. Security limits typically include voltage thresholds, and limits associated with feeder thermal capacity and generator reactive power output. In many power systems, however, point-to-point transfer is not restricted by steady-state limits, but by undesirable dynamic behaviour following large disturbances. The post-disturbance operating point certainly must be viable; but it is also important to ensure that the system can safely make the transition from the pre- to the post-disturbance operating point. Here, the authors describe dynamic ATC, which is concerned with calculating the maximum increase in point-to-point transfer such that the transient response remains stable and viable.