What would make the IRU fail so suddenly the autopilot would automatically disconnect (as per cappt's experience)? What would cause pitch angle to be extremely misleading?
Bad sensors? Icing on sensors? Sensors falling off in flight? Broken gyros? Is this a maintenance issue?
Right now the aircraft is pretty much frozen solid into the ice and snow in northern Sweden. Any investigation regarding instruments left up there would have to wait until spring.. that would be May at the earliest that far up north.