A ram air fan (RAF) assembly is provided and includes a ram air inlet, a heat exchanger disposed in the ram air inlet, an RAF disposed in the ram air inlet to drive airflow through the heat exchanger, a sensor disposed in the ram air inlet proximate to the RAF and a controller. The controller is operably coupled to the RAF and the sensor and is configured to drive rotations of the RAF to achieve a target RAF rotational speed in accordance with a determination that a reading generated by the sensor is indicative of a surge event.