Anybody know what this is?

def atm(h):
    j = 2.25577e-5
    k = 5.25588
    p = 101325
    return p * (1 - j * h) ** k


Looks like calculating pressure at altitude h. See Pressure altitude - Wikipedia

1 Like

Good call! What was the first clue?

Next question, how does this relate to Mach at altitude?

Not to mention temperature variant. That just adds to the problem of figuring out the speed of sound. We’re all very happy with 20 degrees Celsius at sea level.

There is a logarithmic relationship in play here since the speed of sound nearly levels off at 1062 kph after 35000 ft altitude.