What information does a mach meter present?

A mach meter provides the ratio of the aircraft's true airspeed to the speed of sound in the surrounding air. This is important for pilots and engineers because it allows them to assess how close the aircraft is to the speed of sound, which can affect aerodynamic performance and safety. As an aircraft approaches Mach 1, changes in control and stability characteristics can occur due to compressibility effects, which are crucial factors in high-speed flight.

The other options refer to different measurements that are not related to the function of a mach meter. The altitude of the aircraft is typically indicated by an altimeter, while air temperature at cruising altitude is shown by a temperature gauge. The fuel consumption rate is tracked by a fuel flow meter or gauge, which monitors how much fuel the engines are using over time. Each of these readings serves a different purpose and is vital for various aspects of aircraft operation, but they are distinct from the information provided by a mach meter.