In cruise planning, which airspeed is typically used and why?

• A. Indicated Airspeed is used for cruise planning.
• B. Calibrated Airspeed is used for cruise planning.
• C. True Airspeed is used for cruise planning because it reflects density and altitude effects.
• D. Equivalent Airspeed is used for cruise planning.

Answer: (C)

In cruise planning, you plan using True Airspeed because it is the actual speed of the aircraft through the surrounding air, and that speed changes with air density and altitude. True Airspeed corrects the instrument reading for how the air is behaving—as you climb, the air becomes thinner and often cooler, so the same indicated speed corresponds to a higher speed through the air. That speed through the air is what determines how much fuel you burn and how far you can travel in a given leg, especially once you account for winds, which then modify your ground speed. Instrument readings like Indicated Airspeed are just what the pilot sees, without correcting for density or altitude; Calibrated Airspeed fixes installation errors but still isn’t the speed through the air at altitude; Equivalent Airspeed relates to dynamic pressure for structural considerations, not planning metrics. So True Airspeed is the most appropriate value for planning the cruise phase.