Mach

[Mystere IV A]

Why do airliners or militaries use the Mach as a speed measure, when, how, and where does it comes from ?

Fly High :windsock:
:pilot_2:

[Docent75]

The Mach Number is the ratio of the aircraft's speed to the speed of sound at the current conditions. At the speed of sound it is going M 1.0. The speed of sound varies with temperature and altitude. At sea level on a standard day it is about 760 mph, and drops to the mid 600s at 30,000 feet. As an aircraft approaches the speed of sound it enters the transonic region, roughly M 0.8 to M 1.2. The speed where this effects flight is the aircraft's critical mach number. So if ATC wants to hurry the traffic along Mach number is more important thane speed. As I learned in the Hanger Talk Forum, it is used above FL 240.

Ernst Mach was an Austrian physicist in the late 19th Century who studied the speed for sound. He is also one of founders of Gestalt psychology.

[Mystere IV A]

Congrats Docent75, there couldnt be a more precise answer !

Fly High :windsock:
:pilot_2:

[traveler]

:laugh: who needs pilot anyway !

(good on you).

[Mystere IV A]

Is there a pilot in the aircraft ? :grin: :grin:

Come on Trav, even if some decades ago Flight Deck Crew were 5 and now reduced to 2, time has not come yet when we'll get rid of you pilots ..... :cool_2:

Fly High :windsock:
:pilot_2: