The main point is that you will be surprised … fundamentally surprised
The main point is that you will be surprised in severe turbulence … fundamentally surprised - something which you have difficulty in comprehending, believing, far from any expectations based on text or simulation.
Based on about 30sec experience from a preplanned, fully instrumented transit of a 'small' tropical cb in a 2nd gen commercial aircraft, the co-Captain described his experiences as similar to being shot at in a helicopter in 'Nam'.
From trimmed rough airspeed, the aircraft experienced sudden, rapid, and large pitch excursions, with speed and attitude changes ranging from stick-shake / push to overspeed alerting, both nose up and down, within a few seconds. n.b. unseen alpha changes, but recorded; very high rates of change. Normal accelerations (g) were up to but not exceeding the aircraft limits
The brief was to fly attitude - and nothing else. Nothing else would, could have been conceived due to mental freeze due to the severity of surprise, even after the briefed expectation and experience of 'mild' but 'severe' turbulence transits over the tops of cbs.
The most notable effect was the very high stick forces required to recover attitude - the maintain attitude task was essentially pitch upset recovery in both directions. The stick forces and displacement required were those associated with being out of trim between Vra and stall, and opposite at Vmo; very high forces - max manual effort, and large displacements, akin to full range checks.
It is assumed that in modern FBW aircraft the magnitude of force to some extent would be less, but the need for large control inputs might remain.
Then there was roll - at least the aircraft had roll stability vs the need, ability, for control input - judged similarly to be large like pitch, but not made.
The cb just spat the aircraft out of the side of the cloud into 'calm air'.
The safety concept is that the crew will be able to detect and avoid the most severe conditions, but those undetected or not avoided then …
Be prepared to be surprised, unbelievably surprised; fly attitude, do not trim.
Don't think of changing speed to Vra during an event; you will probably be incapable of thought, and any target or reference speed is meaningless. Fly constant attitude - know what these are.
The atmosphere does not read text books, it can throw events at you far in excess of theory.
Fly Vra after exit, be prepared for the next encounter.
As above:- "Severe turbulence causes large and abrupt changes in altitude and/or attitude and, usually, large variations in indicated airspeed. The airplane may momentarily be out of control. Occupants of the airplane will be forced violently against their seat belts."
+ The pilots might be momentarily out-of-control due to the effects of surprise.