A system and method includes a heat exchanger, a ram inlet actuator, and a controller. The ram inlet actuator is configured to control ram air flow from a ram air inlet to the heat exchanger, and the heat exchanger is configured to provide cooling for a bleed air flow. The controller is configured to determine a predicted ram flow based on a bleed air temperature drop across the heat exchanger, a flow rate of the bleed air flow, and a ram air temperature at the ram air inlet. The controller is configured to control the ram inlet actuator based on the predicted ram flow.