My understanding is that attitude is only a reasonable approximation of Angle of attack (assuming winds are parallel to the ground) if you are in level flight.

My understanding is that attitude is only a reasonable approximation of Angle of attack (assuming winds are parallel to the ground) if you are in level flight. My understanding is that with still air, AOA is basically the difference between the attitude and the vertical direction of travel. (i.e. in still air you are climbing at an angle of 5 degrees with the nose pointed up at 10 degrees, your AOA would be 5). So in my possibly flawed understanding the better way to approximate real angle of attack when the wind is parallel to the ground would probably be to take airspeed and rate of climb data, perform trig to get the angle of climb or descent as seen from the air reference frame (cf. airspeed vs groundspeed). Then subtract that from the gyro indicated attitude, and you get an angle of attack approximation that assumes no up or downdrafts. That combination might yield something better to compare against the AOA sensors than just the attitude value. (Although I would agree that if it changing the trim causes the attitude to change but not the AOA sensor output, something is probably wrong.)