Aero Fact: EAS vs CAS vs TAS
Equivalent, Calibrated and True Airspeed differ by compressibility and instrument/position errors; each has proper use.
By AircoreDynamics •
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1 min read
Definition: CAS: IAS corrected for calibration; EAS: CAS corrected for compressibility; TAS: true airspeed.
Physics insight: EAS ∝ √q_dyn; at higher Mach, CAS–EAS divergence increases.
Example: Using EAS in test cards improves comparability.
TAS ≈ EAS √(ρ0/ρ)
Rules of thumb: Use the right speed metric for the task; stay consistent with performance tables.
Common pitfalls: Jumping from IAS to TAS without corrections; ignoring instrument/position errors.
References: Instrumentation references