Originally Posted by
deltajuliet
It's true your AOA increases with altitude, but in the context of this question... May be underthinking this, but would your angle of attack decrease in speed mode so as to maintain the same speed in the climbout? That's why you occasionally need to reduce the speed or go to VS as you near your level-off - to get the nose back up.
Not sure I quite get what you are asking, but I'll attempt an answer.
The thing that governs climb rate in an aircraft is excess thrust available over that is required for level flight at a given speed.
The reason you may have to reduce speed in a climb up to altitude is that the thrust available is insufficient to maintain your desired climb rate, altitude, and airspeed at the same time.