Question

Given a standard day, at what altitude is the true airspeed of an aircraft approximately twice of what the airspeed indicator reads

Answer 1

40000ftMSL

Explanation:

We know that airspeed is measured using a pilot tube

And the air pressure is a function of density given as

Pressure= 1/2 xdensityx V²

So at 40,000ftMSL

Is this is replaced for V in the equation then the density of air will be 1/4 that of sea level

So since we are deriving velocity from pressure and pressure is 1/4 so the velocity Will be half of its pressure since velocity is squared from The equation above