What should be confirmed during the preflight check for the Heartsine AED?

The correct choice highlights the importance of ensuring that the HeartSine AED is operational before a flight. The presence of a green light that flashes indicates that the device is in good working order and ready to be used in the event of a medical emergency. This flashing light is a visual cue that confirms the AED has passed its self-check diagnostics, which is essential for the device's reliability when needed.

While confirming that the device is fully charged, ensuring preparedness for immediate use, and checking that all pads are intact are also important aspects of a preflight check, the flashing green light serves as the most immediate and critical indicator of the AED's operational status. A device without a flashing green light could suggest potential issues, making this step vital for safety and compliance in emergency readiness. Ensuring that this visual cue is checked can be the difference in timely response during an emergency situation aboard the aircraft.