What is the difference between Angle of Incidence (AoI) and Angle of Attack (AoA)? Following discussion here, I am still confused about the difference between AoI and AoA. As I read in many references and watched in many YouTube videos especially this one:
1). AoI is tje angle between the longitudinal axis and the chordline as per design/manufacture. It says normally AoI designed/manufactured is six degrees. AoI remains constant as it is fixed relative to the fuselage.
2). AoA is the angle between the chordline and the RELATIVE AIRFLOW. AoA changes in flight.


My confusion is with the meaning of the RELATIVE AIRFLOW. This phrase confuses me. In my opinion, airflow produced by the propeller or the turbines flows parallel to the longitudinal axis, or at least it has fixed angle, also as per designed too.

To avoid a repetitive question, I want to give this situation.
1). During take off of an airplane, from the airplane start moving until it left the ground, what is the RELATIVE AIRFLOW?
2). After the airplane takes off and during climb, what is the RELATIVE AIRFLOW?
3). During level flight (cruise with constant altitude), what is the RELATIVE AIRFLOW?
4). During approach to land until touching ground, what is the RELATIVE AIRFLOW?

What is actually that AIRFLOW?

I apologize if there are too many questions. It is actually just one. Just to make sure that you will not confuse to read and I will not get confused to read your explanation as product of unclear question.

Before I post this question, I have search if someone have posted previously. But I didn't find the same question.
Angle of Incidence is fixed by the designer of the aircraft. It does not change in flight.

Angle of Attack is the angle between the chordline of the wing and relative airflow during flight.



That is definitely something that changes during operation of the aircraft in flight. Consider slow flight, for example. You reduce power and raise the nose to reduce airspeed. The direction of the airflow remains the same, but the angle between the airflow and the wing chordline, the Angle of Attack, increases. Raise the nose too much (and hence increase the AoA), and the airflow will separate from the top of the wing and you will stall.

On aircraft like Cessna trainers, the stall warning is a very basic indicator of Angle of Attack, to warn you when you are about to stall.



More advanced Angle of Attack indicator systems use a vane to measure the angle of the relative airflow, and give you more information about AoA.