What provides fuel low indication in an aircraft?

The presence of an optic sensor at 110 lbs on each side of the aircraft's fuel system is the most effective and reliable means of providing a low fuel indication. This type of sensor utilizes light to measure the fuel level, and it is calibrated to alert the pilot when the fuel drops to critical levels, specifically at or below 110 lbs. This ensures that the pilots are informed well in advance of running dangerously low on fuel, allowing for better planning and safer operation of the aircraft.

Optical sensors offer several advantages, including accuracy and the ability to reduce errors caused by fuel dynamic changes, such as fuel slosh during flight. This technology provides precise readings even under varying conditions, enhancing the pilot's ability to respond to fuel status effectively. In contrast, other options may not deliver as clear or timely indications of low fuel levels due to factors like sensor calibration limits or reliance on less direct measurement methods.