The amount of fuel in the tanks of a Boeing 767 is computed by the Fuel Quantity Indication System (FQIS) and displayed in the cockpit. The FQIS on the aircraft was a dual-processor channel, each independently calculating the fuel load and cross-checking with the other. In the event of one failing, the other could still operate alone, but in that case, the indicated quantity was required to be cross-checked against a floatstick measurement before departure. In the event of both channels failing, there would be no fuel display in the cockpit, and the aircraft would be considered non-serviceable and not authorized to fly.