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Word of the Month - Total Block Fuel Consumption

By Ian Brown, Editor - Bits and Pieces, EAA 657159

In reading the information available about the electric green taxiing system, the author mentions 4 percent savings in "total block fuel consumption". It's unclear whether definitions like this are significant for GA, but digging into the term resulted in discovering the following information.

Block fuel is the total fuel onboard prior to taxiing. Therefore, the total block fuel consumption refers to the total amount of fuel consumed during taxiing at both ends of the flight, and the flight itself, so a reduction of 4 percent is an overall savings of that amount on the fuel used.

There are many other terms used by pilots of heavier aircraft. When they switch from one aircraft to another for a living, it is really important to have a common language. Burn-off fuel refers to the fuel for taxiing and the planned fuel burn en route. You could argue that "total burn-off fuel consumption" might be a better term. Perhaps one of our readers could comment on whether burn-off fuel includes taxiing fuel required at the destination.

The term ballast fuel is interesting but really irrelevant to light aircraft since it refers to fuel that is used purely for ballast and may not be used or jettisoned during flight. It is used purely to keep the aircraft inside the flight envelope. One assumes that it can also be recirculated for use when other loading conditions prevail. It is the same as ballast bags which have been loaded on one passenger flight the author experienced. You wouldn't jettison those, either. One wonders whether ballast fuel is ever needed in light aircraft, perhaps with a full baggage compartment and a lightweight solo pilot.

Reserve fuel is an important term for every pilot. It refers to fuel kept as a safety margin throughout the flight for diversions, holds, and simply so that you know you have a certain flight time in reserve after the worst-case planned arrival time.

Trip fuel is the amount of fuel you expect to use between takeoff and landing, i.e. excluding amounts required for taxiing.


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