When smoke is present on any corridor, the relevant Smoke Detector (D) sends a signal to the Control Panel (A).
The panel then sends a signal to the respective AOV on the 'fire' floor, and this opens within 60 seconds to allow smoke to vent out through the building.
At the same time that the shaft vent is opened, the Control Panel sends a signal to the Stirling head-of-stair vent (S) to open, thereby allowing the ingress of replacement cooler air.
As escaping occupants leave the corridor, this replacement air is naturally drawn into the corridor, which in turn aids the flow of smoke out through the AOV.