In post #710 I ok'd following quote from a TSB incident report:
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.
Thinking about it further, I felt I ought to correct that in the interest of an understanding of the flight mechanical aspects of the phenomenon.
Actually only the first sentence is entirely correct. The second sentence is sensorially correct during acceleration on the runway, although it is perhaps somewhat unlikely that it would cause a strong sensation of climbing in an experienced pilot. However, when the aircraft nose is raised in flight, the airplane will actually start climbing and the acceleration will reduce. The reduction of acceleration tilts the perceived attitude forward by the same amount as the real pitch change is nose-up. In other words, the somatogravic illusion is then that the pitch attitude has not changed. A similar argument applies in reverse when the nose is pitched down.