What device measures fuel flow in an aircraft?

The device that measures fuel flow in an aircraft is indeed the fuel flow transmitter. This instrument is specifically designed to monitor the rate at which fuel is flowing through the aircraft's fuel system. It typically converts the mechanical movement or pressure of the fuel into an electrical signal, which can then be processed and displayed on the cockpit instruments for the pilots to monitor.

Fuel flow transmitters are essential for providing real-time data regarding fuel consumption, which is crucial for flight planning, fuel efficiency calculations, and ensuring that the aircraft has sufficient fuel for its operation. This information aids pilots in managing fuel reserves and optimizing performance.

In contrast, other options serve different purposes. A fuel flow valve regulates the flow of fuel but does not measure it; a fuel pressure gauge indicates the pressure within the fuel system, which is not a direct measurement of flow rate; and a fuel quantity sensor measures the amount of fuel in the tanks, not the flow rate. The unique functionality of the fuel flow transmitter makes it the correct choice in this context.