An aircraft flying below the tropopause descends at a constant True Airspeed, its Mach. No. will
- stays constant.
- rise.
- decrease.
Explanation from PART66Online
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.
S
Skap92 asked · 10 Jan 2013
why? If TAS is costant the Mach No. will be constant for me. Help?
Community Comments (3)
P
PART66Online
10 Jan 2013
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: lionels.orpheusweb.co.uk/Graphics/ATD...
S
Skap92
10 Jan 2013
Thank you!
O
onu93
24 Feb 2014
Thanks!
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