What distinguishes Fuel Quantity (FQ) from Fuel Reference (FR)?

Fuel Quantity (FQ) refers specifically to the actual amount of fuel present in the aircraft, which is provided by the Data Acquisition Unit. This system utilizes sensors and physical measurements to determine the real-time fuel levels in the tanks. The FQ is essential for the flight crew to know how much fuel is available for flight planning, ensuring that they can operate safely within the aircraft's limits.

On the other hand, Fuel Reference (FR) is derived from calculations made by the Flight Management System (FMS). This figure typically represents the estimated fuel required for a flight, accounting for variables such as flight plan, weather conditions, and operational parameters. FR aids in strategic planning and helps in making informed decisions regarding fuel usage and reserves.

Understanding the distinction between FQ and FR is crucial for pilots, as it allows them to interpret their fuel resources correctly—using FQ for immediate fuel status while relying on FR for projected fuel consumption based on flight data.