Takata
I agree I have overstated the BEA proven case so far with regard to control authority, however, if you had ever flown an aircraft like the A-4 Skyhawk (which was a wonderful and fun flying machine by the way) you would understand the limitations of nose down elevator against a large THS in (nearly) full nose up trim. As I stated earlier, the elevator is more like a trim tab in comparison of actual relative control authority.
The reason the crew did not understand what they were looking at was this:
This illustration come from Davies excellent book: "Handling the Big Jets."
The crew is trying to figure out if they are seeing a pinball show from hell caused by crazy computers or the real thing.
The attitude is probably fairly stable in pitch by the time the Captain re-enters the cockpit and the likely lateral imbalance problem probably seems not much worse than it was initially.
The only big clue should have been the rapidly unwinding altimeter. BTW, I don't remember at the moment but:
The standby altimeter. Is it the old fashioned kind with the pointer that goes around for every 1000 feet lost, or is it just another digital display with rapidly changing digits?
Under stress, the old fashioned kind is far better for drawing attention to itself. Sometimes digital is not better for absorbing information.
Are you able to answer the question about having to fly the aircraft laterally while staying off the pitch axis that I asked earlier?
I get the feeling that this aircraft needed almost continuous lateral input to fly wings level, and that the forces required on the stick were higher than just fingertip level. With the RH seat flying and a heavy right wing, the tendency might be to cup the stick with the palm, and in this mode, it would be very easy to make aft stick inputs as well.
Why right wing heavy? Who knows (Maybe a change in rudder trim as they switched rudder control modes), but if you will note, all turns made after the initial loss of control were to the right.