Physics

True Airspeed Calculator

Estimate true airspeed from indicated airspeed and altitude.

Calculated Output

True airspeed (kn) 174

Formula: TAS ≈ IAS × (1 + 0.02 × altitude/1000)

Step-by-Step Breakdown

1. Values used:

2. Indicated airspeed = 150 kn

3. Altitude = 8,000

5. True airspeed = 174kn

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The math behind it

A common rule of thumb adds about 2% per 1000 ft to the indicated airspeed.

150 kn indicated at 8000 ft → about 174 kn true.

Why does the airspeed indicator read low?

It measures dynamic pressure, which falls as air density drops.