An aircraft flying below the tropopause descends at a constant True Airspeed, its Mach. No. will
- stays constant.
- rise.
- decrease.
Explanation
Below the tropopause temperature rises during a descent, which increases the local speed of sound. Since Mach number is true airspeed divided by that local sonic speed, holding TAS constant while the denominator grows means the Mach number must decrease.
Skap92 asking:
why? If TAS is costant the Mach No. will be constant for me. Help?
Community Comments (3)
D
dimky Posts: 514 10.01.2013 / 11:29
TAS is constant but temperature below the tropopause not constant. Speed of sound depends on temperature, therefore Mach number depends on temperature, so it will decrease. Check this table: http://lionels.orpheusweb.co.uk/Graphics/ATDataL.gif
S
Skap92 Posts: 1 10.01.2013 / 11:33
Thank you!
O
onu93 Posts: 2 24.02.2014 / 17:50
Thanks!
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