What is the purpose of an "airspeed indicator" in flight?

The purpose of an airspeed indicator is to measure the speed of the aircraft relative to the surrounding air. This is crucial for pilots as it helps determine the aircraft's performance during various stages of flight, including takeoff, cruising, and landing. Understanding airspeed allows pilots to make informed decisions regarding their flight path, ensuring safe operation and adherence to aerodynamic principles.

For instance, knowing the stall speed is vital for maintaining safe flight, and having the correct approach speed during landing improves control and safety. The airspeed indicator presents this information visually, enabling pilots to monitor their speed in real-time against performance charts and guidelines.

Altitude changes, fuel efficiency, and engine temperature, while important metrics in flight operations, do not relate to the primary function of the airspeed indicator. These functions are measured by different instruments: altimeters assess altitude, fuel flow indicators track fuel efficiency, and engine temperature gauges monitor engine performance.