Which component typically alerts pilots to low fuel levels?

The component that typically alerts pilots to low fuel levels is the fuel quantity warning light. This system is specifically designed to provide a visual warning to pilots when fuel levels drop below a predetermined threshold, indicating a potential issue with fuel management. The functionality of this warning system plays a crucial role in ensuring flight safety, as it allows pilots to take corrective action before the fuel levels become critically low.

In contrast, while the fuel gauge gives an indication of the current fuel quantity, it does not provide a specific alert for low fuel conditions. The pitch trim indicator is used to show the position of the trim tabs and does not relate to fuel levels at all. The autopilot system primarily manages the aircraft's flight controls and does not monitor fuel levels directly. Therefore, the fuel quantity warning light is key for alerting pilots to low fuel scenarios, making it the correct choice in this context.