What is indicated airspeed (IAS) primarily used for?

Indicated airspeed (IAS) is primarily used to measure the speed at which an aircraft is flying through the air. This measurement is crucial for pilots, as it directly affects aircraft performance, including lift generation, stall speed, and the operational limits of the aircraft. IAS is derived from the aircraft's pitot-static system, which measures the dynamic pressure of the air as the aircraft moves forward.

When flying, maintaining the correct IAS helps pilots ensure that the aircraft remains within safe operating conditions. For instance, knowing the IAS is essential for executing maneuvers, navigating through different phases of flight, and understanding the amount of lift being generated. Thus, IAS serves as a key reference for flight safety and performance, making it an indispensable aspect of aviating.

In contrast, the other options relate to different measurements or operational parameters. Fuel consumption depends on various factors, including engine performance and efficiency and is not calculated directly from IAS. Altitude above sea level is determined using barometric pressure and is not directly associated with IAS. Wind velocity assessment relies on different instruments and calculations, such as groundspeed and wind direction, rather than IAS directly.