Question

Equivalent Air Speed (EAS) is

• A. Indicated airspeed corrected for installation and instrument errors
• B. The speed of the aircraft relative to the ground
• C. The actual speed of the aircraft through the air mass
• D. Calibrated airspeed corrected for adiabatic compressible flow at a particular altitude

Hint:

Important airspeed definitions: \[ \boxed{ \begin{aligned} \text{IAS} &\rightarrow \text{Indicated Air Speed} \text{CAS} &\rightarrow \text{IAS corrected for instrument and position errors} \text{EAS} &\rightarrow \text{CAS corrected for compressibility} \text{TAS} &\rightarrow \text{EAS corrected for air density} \end{aligned} } \]

Answer 1

The Correct Option is D

Step 1: Recall the definition of Equivalent Air Speed (EAS). Equivalent Air Speed (EAS) is defined as \[ \boxed{\text{Calibrated Air Speed (CAS) corrected for compressibility effects}.} \] It represents the airspeed at sea-level standard density that would produce the same dynamic pressure as the aircraft experiences at its actual altitude.

Step 2: Analyze the given options.
• Indicated Air Speed corrected for instrument and position errors gives Calibrated Air Speed (CAS).
• Speed relative to the ground is Ground Speed (GS).
• Actual speed through the air mass is True Air Speed (TAS).
• Calibrated Air Speed corrected for compressibility effects gives Equivalent Air Speed (EAS). Therefore, \[ \boxed{\text{Calibrated airspeed corrected for adiabatic compressible flow at a particular altitude}} \] is the correct answer. Thus, \[ \boxed{(D)} \] is the correct answer.