What is the main purpose of the fuel gauge?

The primary function of the fuel gauge in an aircraft like the Cessna 172 is to indicate the amount of usable fuel remaining in the tanks. This vital information helps the pilot manage fuel consumption and maintain awareness of how much fuel is available for flight operations. Reliable fuel quantity readings are essential for flight planning, ensuring the aircraft has adequate fuel for the duration of the flight and for any potential diversions.

While fuel pressure measurement is important for the operation of the fuel system, it is not the purpose of the fuel gauge. Checking for fuel leaks is also crucial for safety but does not relate to the fuel gauge's function. Lastly, calculating the fuel burn rate involves more complex monitoring and requires additional instruments rather than just the fuel gauge itself. Thus, the fuel gauge's primary responsibility is to inform the pilot of the remaining usable fuel, making it essential for safe flight operations.