Many years ago a Convair 580 flew into the sea within seconds of lifting off from Auckland airport. Both pilots died in the accident. It was a dark night and once airborne the crew would have been on instruments. I don't know if the investigators considered they both could have been affected simultneously by somatogravic illusions.
But the investigators did find out that the copilot who was conducting the take off was on her first flight as handling pilot. Also in several previous flights the copilot's artificial horizon instrument was defective in that it displayed erroneous indications in roll and pitch attitudes. Not only that, but the instrument was left in place while awaiting a replacement. The situation had been like that for a few weeks.
The investigators asked other company pilots about their experiences of flying with the captain who was also the chief pilot. Take off's in the Convair required the use of take-off flap. Retraction of flap after take off was normally done above 500 feet due to the significant nose down pitching moment that was a characteristic as the flaps came in. Notwithstanding this characteristic, the captain was well known for his habit of selecting flaps up almost immediately after the gear was selected up and this was as low as 100 ft.
The investigation concluded that although the copilot had never flown the Convair - apart from observation flights - this was her first flight actually handling the controls. It was a night IMC departure with a known defective artificial horizon on her side. The action of the captain in selecting flaps up soon after lift off, would have caused a nose down change of pitch that may not have been noticed by the copilot faced with a faulty artificial horizon. To a new copilot this would have been an impossible task to pick the problem. The captain was at fault for putting her in a situation that would have taxed even a highly experienced instrument pilot.
The Convair 580 was a powerful aircraft with excellent acceleration during take off. Maybe somatogravic illusion was a contributory factor in the accident. But in this particular accident there were more compelling facts that came to light. Take your pick...