If you are building a simulator, do you mean you are deriving the aerodynamic data from flight test - in which case you need a way to measure or deduce angle of attack - or are you building the simulation code (equations of motion, etc.) and have a defined aerodynamic data set.
If the former you are going to have a problem with the data you have because you don't know what the local wind is. Therefore you have two parameters measured relative to the air mass (airspeed and vertical airspeed) and one in the earth axis reference (pitch attitude). If you can't relate the air mass to the earth (wind) then you will have to guess and that will cause potentially large errors.
If you are building equations of motion then you're asking a different question. But again the attention to detail of the reference frames is vital - you can easily make the aircraft unstable/unflyable without careful maintenance of the references.
Let us know which it is...