What type of warning system can prevent a fuel tank from being fully exhausted before switching to another tank?

The most effective system for preventing a fuel tank from being fully exhausted before switching to another tank is a fuel level indicator. This system provides real-time information regarding the amount of fuel remaining in each tank, allowing pilots to monitor fuel levels and make informed decisions about when to switch tanks. By showing the current fuel level, it helps ensure that a tank does not run dry, which could lead to engine failure or other operational issues.

In contrast, while a fuel flow measurement system might provide data about how much fuel is being consumed, it does not give a direct indication of how much fuel remains in the tank. A fuel pressure warning signal system alerts pilots if there is an issue with fuel pressure but does not provide information specifically related to the quantity of fuel left. A fuel temperature monitoring system helps manage the risks of fuel vaporization or icing but is not designed to indicate fuel levels. Thus, the fuel level indicator is the system that directly addresses the need to manage fuel usage effectively during flight operations.