Originally Posted by GerardC
I agree with "BOAC", there WAS a turbulence increase but, since they only elected to reduce speed at 2h 08, the level of turbulence before that time must have been very benign ideed.
Just a point to consider, beyond agreeing with many that there is quite a bit of information lacking.
The conditions
previous to upset are not as important (in terms of understanding pilot response) as conditions during the period 2:10 to 2:14.
As we all know, conditions change in the vicinity of big buildups. Sometimes those changes are significant. The crew expected some change in conditions before the course correction of 12 degrees. There is no guarantee that their correction was sufficient, though it may have been. It also could have been insufficient, with a result of flying into turbulence that they'd expected to avoid by the course change.
One useful piece of non-evidence that we can work with is lack of evidence of an action taken: absence of further warning to the CC to secure the cabin for turbulence.
I do not feel it reasonable to rule out the possibility that
a change in condition was coincident to the other problems they encountered.
The well asked question is then: why no alert to the cabin crew? When things get rough, it is standard practice to have the CC secure the cabin.
Aviate, navigate, communicate is also standard. Crew got very focused on aviate, and were having sufficient trouble with aviate
to summon the Captain. That is a possible accounting for the non-call to the CC to secure the cabin.
Admittedly, this doesn't give an answer, it just raises another question. So be it, only so much information to work with.