Originally Posted by
busTRE
Henra
At the limit of the envelope the margin can be as little as 30kts TAS from Vls to Mmo. MAch and GS have nothing whatsoever to do with it.
The reference was at FL350 @ ~200t and for the Mach assuming still air to show how wide the difference is regarding TAS.
at FL380 it was probably indeed down to 30kts but going there was not a good idea in the first place. The idea of peplum to go to a lower altitude where the margin is wider and to go to a reasonable GS is better than what happened here, even though not perfect. It is not a good strategy to fly the plane by GS but it could be used to check plausibility of one's own assumptions about what is going on. GS can't be trumped and if GS says 110kts, you get a clear pitcure about what's wrong.
@Zorin_75:
No contradiction:
For flying it's IAS that counts.
Inertia (i.e. Decelleration/accceleration) happens based on TAS. (Rho/2 * V_TAS ^2).