The TSB's Finding that the Transat captain PF experienced somatogravic illusion is somewhat questionable. In 1.11.4 Somatogravic Illusion, they write:
(...) When the aircraft is accelerating, the sense organs of the inner ear of the pilot send a signal to the pilot’s brain that is interpreted as tilting backwards instead of accelerating forward. If the aircraft nose is simultaneously raised, the pilot has a very strong sensation of climbing. The illusion of false climb tends to lead the pilot to lower the nose and descend. The aircraft then accelerates and the illusion can intensify.
That is o.k., but doesn't describe what happened in the incident. The airplane attitude started to decrease at about 1440:32 EST, when the airspeed was actually decreasing. At about 1440:44 EST the airplane started to descend. Between about 1440:41 and 1440:48 the airspeed increased by about 33 kt IAS, 30 kt TAS in 7.3 seconds, an acceleration of 0.21 g. Yet their figure 10 shows a perceived attitude that is 35° greater than the real attitude, i.e. corresponding to an acceleration of 0.57 g. Difficult to understand.
