Originally Posted by Dan64456

In this example - I usually fly an A321... If I'm cruising at constant flight level 360, and use mach .81 as the speed reference the bug on the speed tape would be for example 275kts... Sometimes I have to change from .81 to .80 to .81 again to "reset" the speed so it doesn't go overspeed on me... sometimes comes back with a number different than 275. Almost as if the plane doesn't constantly calculate mach speed until you change it again. Is it this way in real life or just flight sim x? And just so I understand right, mach speed depends on temp?

Thanks all... let me know if the question needs clarifying.