What happens when the altimeter setting is changed during climb?

• A. The airspeed indication changes.
• B. The altitude indication changes to reflect the new pressure reference.
• C. The vertical speed indicator resets to zero.
• D. The Mach number changes.

Answer: (B)

The main idea is that the altimeter uses a pressure reference to convert ambient pressure into an altitude reading. When you change the altimeter setting, you’re changing that reference pressure, so the altimeter recalculates and displays a different altitude even though your actual altitude hasn’t changed.

During a climb, adjusting the setting will cause the altitude indication to shift up or down depending on the new reference. If you raise the pressure setting, the readout tends to go lower; if you lower the setting, the readout tends to go higher. The other instruments—airspeed indicator, vertical speed indicator, and Mach number—aren’t directly affected by changing the altimeter setting, since they rely on the pitot-static system and speed of sound rather than the altitude reference.