Airspeed Calculator
250 knots CAS at 10,000 ft is a true airspeed of 288.702 kn, about 15 % faster because the air is thinner.
288.702315539368 kn
Full answer, then cut to fewer decimals (not rounded):
- 288.702315539368 kn
- 288.70231553936 kn
- 288.7023155393 kn
- 288.702315539 kn
- 288.70231553 kn
- 288.7023155 kn
- 288.702315 kn
- 288.70231 kn
- 288.7023 kn
- 288.702 kn
- 288.70 kn
- 288.7 kn
- Calibrated airspeed CAS
- 250 kn
- Equivalent airspeed EAS
- 248.0957762 kn
- Mach number
- 0.4522751173
- TAS
- 534.6766884 km/h
- Impact pressure q_c
- 10498.22305 Pa
- Dynamic pressure ½ρV²
- 9977.501541 Pa
Step-by-step solution
- At 3048 m: p = 69681.64162 Pa, ρ = 0.9046369066 kg/m³, a = 328.3870738 m/s
- q_c = p[(1 + 0.2M²)^3.5 − 1]; CAS = a₀√(5[(q_c/p₀ + 1)^(2/7) − 1])
- M = 0.4522751173 → TAS = M a = 148.5213023 m/s; EAS = TAS√σ = 127.6314937 m/s
Airspeed Formula
EAS = TAS √(ρ/ρ₀), q_c = p[(1 + 0.2M²)^3.5 − 1]
CAS = a₀√(5[(q_c/p₀ + 1)^(2/7) − 1]); a₀ = 340.294 m/s, p₀ = 101325 Pa
Worked Example
250 knots calibrated airspeed at 10,000 ft pressure altitude:
- At 3048 m: p = 69681.64162 Pa, ρ = 0.9046369066 kg/m³, a = 328.3870738 m/s
- q_c = p[(1 + 0.2M²)^3.5 − 1]; CAS = a₀√(5[(q_c/p₀ + 1)^(2/7) − 1])
- M = 0.4522751173 → TAS = M a = 148.5213023 m/s; EAS = TAS√σ = 127.6314937 m/s
Equivalent airspeed EAS: 248.0957762 kn · Mach number: 0.4522751173 · TAS: 534.6766884 km/h · Impact pressure q_c: 10498.22305 Pa · Dynamic pressure ½ρV²: 9977.501541 Pa
GATE tip
For incompressible questions, EAS = TAS√σ with σ = ρ/ρ₀. A rule of thumb: TAS exceeds CAS by about 2 % per 1000 ft of altitude at moderate speeds.
More Atmosphere and Airspeed Calculators
-
Standard Atmosphere Calculator
T = 288.15 − 0.0065h, p = 101325 (T/288.15)^5.2559
troposphere to 11 km; isothermal 216.65 K from 11 to 20 km; ρ = p/(RT), a = √(γRT)
Example: The standard atmosphere at 5000 m: Temperature T = 255.65 K.
-
Mach Number Calculator
M = V / a, a = √(γRT)
γ = 1.4 and R = 287.05 J/(kg·K) for air; T in kelvin
Example: An aircraft at 250 m/s true airspeed at 11 km: Mach number M = 0.847258.
Frequently asked questions
What is the difference between CAS and EAS?
CAS assumes sea-level compressibility; EAS corrects for compressibility at the actual altitude. They are almost equal at low speed and altitude, and EAS is a little lower at high speed.
Why do pilots fly by indicated airspeed?
The wing responds to dynamic pressure, which IAS/CAS tracks, so stall and limit speeds stay the same at every altitude in CAS while TAS rises.
Sources
- The International System of Units (SI), 9th edition (SI Brochure), Bureau International des Poids et Mesures .
Last reviewed: . Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.
Cite this page
APA
Scientific Converters. (2026, October 15). Airspeed Calculator. Retrieved October 25, 2026, from https://scientificconverters.com/calculators/airspeed-calculator/
IEEE
Scientific Converters, "Airspeed Calculator," scientificconverters.com. Accessed: Oct. 25, 2026. [Online]. Available: https://scientificconverters.com/calculators/airspeed-calculator/