So does mach increase or decrease with altitude? I thought that it decreased because if you are going mach 1 at 1000 feet you are going much faster than if you are going mach 1 at 36,000 feet. Why are the fellas on the gouge saying mach increases with altitude? TAS is greater with altitude and the speed of sound is lower so are they saying that mach NUMBER increases with altitude even though actual mach decreases?
I think they mean that for a given IAS your mach will increase with altitude. So if you maintain 320knots indicated at 1000 feet and 320knots indicated at 37,000 your mach will be higher.