What should be considered when investigating an abnormal fuel quantity indication?

• A. Rely on captain's memory and skip checks
• B. Cross-check with other indicators, validate with the fuel schedule, and consider gauge or wiring faults and tank isolation
• C. Reroute to the nearest alternate airport without checks
• D. Increase cargo load to balance CG

Answer: (B)

When something looks off with fuel quantity, you validate the reading with multiple sources and the flight plan. Start by cross-checking with other indicators: compare the reading against other fuel gauges, the fuel flow/totalizer, and the indications from other tanks (left, right, and center as applicable) to see if the anomaly is isolated or widespread. Then verify against the fuel schedule (the planned onboard quantity) to determine if the display is reasonable for the expected fuel state. If a discrepancy remains, consider that the issue may lie with the measurement system itself—gauge or wiring faults, calibration drift, or probes unlikely to read correctly. Tank isolation can also cause readings to misrepresent actual fuel if a tank is not being monitored properly, so confirm valve positions and isolation status. This approach helps distinguish between an actual fuel state and instrument or system faults, supporting safe decision-making and appropriate follow-up actions.