Definition
An electronic instrument that calculates and displays fuel quantity data by integrating fuel flow over time. It typically shows fuel remaining, fuel used, and (when paired with GPS or airspeed inputs) time and distance the aircraft can fly on the fuel onboard. The totalizer is initialized by the pilot entering the fuel quantity at start-up, and it then subtracts fuel as it is burned.
Plain English
A digital device in the cockpit that keeps a running tally of how much fuel has been burned, how much is left, and how long the aircraft can keep flying. The pilot tells it how much fuel is onboard at the start, and it counts down from there based on actual fuel flow.
Context Anchor
Seen on cockpit fuel management displays, engine monitors, and some flight planning equipment.
Derivation
From 'totalize,' meaning to add up or sum. The instrument totals fuel flow over time, hence 'totalizer.'
Why Pilots Care
It provides a running total of fuel used, allowing pilots to cross-check against planned burn and tank gauges to avoid unexpected fuel exhaustion.
Analogy
It works like the meter on a gas pump in reverse: instead of adding up fuel going into a tank, it adds up fuel being used by the aircraft.
Intuition Check
Do not assume a fuel totalizer is the same as a fuel tank gauge. A tank gauge senses fuel in the tank; a fuel totalizer usually calculates fuel used and fuel remaining from fuel flow.
Example Sentence 1
After fueling to the tabs, the pilot updated the fuel totalizer to 50 gallons before engine start.
Example Sentence 2
After the flight the mechanic downloaded the fuel totalizer logs to compare actual consumption against the flight plan.