When both the BLOWER and EXTRACT switches are selected to OVRD, what configuration is achieved?

Selecting both the BLOWER and EXTRACT switches to OVRD configures the environmental control system to operate at maximum capacity in response to smoke or fire detection within the aircraft. This setting allows for the continued operation of the blowers while also ensuring that the extract fans are functioning at their highest efficiency. The primary goal of this configuration is to mitigate smoke concentration by exhausting it from the aircraft, thereby aiding in the crew's efforts to maintain a safe environment.

In this context, the BLOWER and EXTRACT fans work together to clear smoke and improve visibility and air quality inside the cabin or cockpit. Thus, this configuration is critical during an emergency situation where smoke has been detected, facilitating rapid and effective ventilation.

Alternatives such as NORMAL, INTERMEDIATE, or OPEN do not provide the immediate and powerful response necessary for managing smoke scenarios, as they either maintain standard operating conditions or do not maximize airflow effectively.