Does this web page really correctly depict the most common usage of the term "incidence" in the French language in the aviation context, in the context of speaking of an entire aircraft and not just an isolated part such as a wing section in a wind tunnel? Is the label "incidence" really attached to the correct angle?
I am referring specifically to the second airplane diagram, i.e. the first diagram that shows an airliner. Note that the text above the diagram uses the phrase "en croisière" which is a reference "cruising", presumably horizontal, flight. The line x-x' appears to represent the longitudinal axis of the aircraft, so it appears that the angle labeled "incidence" represents the angle between the flight path/ relative wind and the longitudinal axis of the fuselage, not the angle between the flight path/ relative wind and the chord line of the wing, which would clearly be a larger angle.
In fact the text above the diagram explicitly states "L'incidence est définie par rapport à l'axe de l'aéronef et non de la voilure.", which translates to something like "The incidence is defined relative to the axis of the aircraft and not of the wing."
Shouldn't the angle labeled "incidence" be the angle between the flight path/ relative wind and the chord line of the wing rather than the angle between the flight path/ relative wind and the fuselage?
Or is it just a matter of arbitrary convention, meaning that either usage would be equally appropriate?
(One way to concisely answer this question might be "The correct usage of 'angle d'incidence' in the French aviation context is exactly identical to the English-language usage of 'angle of attack' (or replace with other appropriate angle as needed) as noted in this ASE answer (give link)." Not all ASE answers have given the same perspective on the most correct usage of this term.)
Note that the angle labeled "angle de calage" is the angle that is called "incidence" in American aviation usage and some or most (but not all) British aviation usage-- the angle between the chord line of the wing and the longitudinal axis of the fuselage. This question is not about whether or not the diagram uses "angle de calage" correctly in the context of French aviation terminology-- it clearly does.
Bonus question-- in the French aviation context, is the term "angle d'attaque" used to mean something different than "angle d'incidence"?