For automatic spoiler extension to occur during a rejected takeoff with the spoilers armed, what must happen?

In the context of the A320 system, for automatic spoiler extension to be triggered during a rejected takeoff with the spoilers armed, wheel speed must exceed a specific threshold while the thrust levers are positioned at forward idle.

When the wheel speed reaches greater than 72 knots, the aircraft recognizes the condition of a rejected takeoff and prepares to deploy the spoilers to aid in deceleration and improve braking effectiveness. This deployment mechanism is critical for safety, as it helps to maintain control of the aircraft and assists in a rapid stop on the runway, particularly in emergency situations.

The specified wheel speed ensures that the aircraft is in a realistic scenario where the control systems can actively respond to a need for stopping. If the speed is below this threshold, the system is still in an initial phase of takeoff, and spoiler deployment would not be deemed necessary or appropriate.

Therefore, the requirement for the thrust levers to be at forward idle ensures that the engines are not actively providing thrust during the rejected takeoff. This setup enables the automatic spoiler extension feature to function accurately, contributing to a safe and controlled deceleration process.