In more advanced aircraft, which instrument may be included in the air data system?

• A. Mach meter
• B. Attitude indicator
• C. Magnetic compass
• D. Tachometer

Answer: (A)

In more advanced aircraft, the air data system can include a Mach number readout because Mach tells you how fast you’re traveling relative to the local speed of sound, which matters a lot at high speeds and with changing altitude. The air data system collects pitot (dynamic) pressure, static pressure, and often a temperature input, then computes true airspeed and the speed of sound to derive Mach. This allows the Mach indicator to be displayed alongside other air data-derived instruments.

The other instruments listed aren’t part of the air data system: the attitude indicator relies on gyros to show orientation, the magnetic compass uses Earth’s magnetic field for heading, and the tachometer measures engine RPM. They serve different systems and don’t depend on pitot-static and temperature data.