Originally Posted by takata
Added to that both Airbus/Air France recommended turbulence penetration mode is Autothrottles OFF while AF447 A/T was kicked OFF by systems at 02.10, consequently, she was certainly not in turbulence penetration mode/speed until this point. Moreover, at 02.10, more than half of the CB system was already crossed, they were not just penetrating it.
Actually, in that perpetual push to make maximum use of automatism, it is not written anywhere in the Airbus documentation to pre-emptively disconnect the A/THR before entering a suspected area of turbulence, maybe it is in the AF documentation ?
The Airbus recommendation to disconnect A/THR applies if severe turbulence is already encountered and only when thrust changes become excessive as per QRH.
Originally Posted by mm43
Which explains why they stated the turbulence penetration speed was M0.78 instead of M0.80 in the A330.
Just to clarify, the recommended speed for severe turbulence for a A330-200 at FL350 is
260 knots IAS which is for reference slightly below Mach.78
But the BBC program mention of Mach.76 is effectively also inexact.