Originally Posted by Minorite invisible
How would American pilots feel, if say French had been the international ATC language and US pilots flying in US Domestic Airspace were forced to learn French in order to fly aircraft inside their own country?
I think you just answered the real issue this all revolves around.
It's mostly about pride and feelings, 2 things IMHO that shouldn't enter the equation.
The other official languages can be perfectly used in communication with ATC but it should be done conditionally.
If in heavily used ,like around commercial
international traffic airports or in continuously busy airspace, English should be the norm.
Nobody cares what language is used between traffic and tower as long as there is no commercial international traffic involved.