What is one of the main functions of an aircraft's Vertical Speed Indicator?

• A. Calculating fuel consumption
• B. Displaying rate of altitude change
• C. Indicating engine temperature
• D. Monitoring external temperature

Answer: (B)

The main function of an aircraft's Vertical Speed Indicator (VSI) is to display the rate of altitude change. This instrument provides pilots with critical information about whether the aircraft is climbing, descending, or maintaining level flight. The VSI measures the rate of change in altitude in feet per minute (fpm) and helps pilots make informed decisions related to ascent and descent during flight phases. By understanding the vertical speed, pilots can ensure a smooth approach for landing or a safe climb away from the ground, contributing to overall flight safety and efficiency.

Other options listed do not align with the primary purpose of a VSI. For instance, fuel consumption, engine temperature, and external temperature are monitored by different gauges and instruments, each serving specific operational needs that do not relate to vertical movement or altitude change.