An aircraft fuel management system providing accurate and comparable measurement and display of on-board fuel quantity, fuel rate and flight time remaining. This system utilizes capacitance method of fuel gaging and fuel mass flow rate derived from both volumetric flow measurement and capacitance density compensation. These separate measurements -- fuel gaging and mass flow rate -- are combined electronically to obtain "flight time remaining" under prevailing flight conditions.
A fill level measuring system for the liquid content of a tank, with a fill level sensor (10, 50) for generating a signal proportional to the height of a point of the liquid level, an additional volume flow sensor (14, 52, 56) for generating a signal proportional to the inflow or outflow, and an indicating instrument (28). To compensate for systematic errors with high-frequency portions, for example due to air turbulence in the case of an airplane, and low-frequency portions, for example due to position changes (climb/descent; upward run/downward run for a motor vehicle) it is proposed to direct the signal of the fill level sensor (10) through a low-pass filter (12) and the signal of the volume flow sensor (14) through a high-pass filter (18), and to sum up both signals before the indicating instrument (28).
