E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Air ones opinions (To).
To state opinions without having firmly based them on proper data. To let them fly loose, like a caged bird.
To ventilate an opinion means to suggest for the purpose of having it duly tested. A conceited man airs his opinions, a discreet one ventilates them, as corn when it is winnowed, and the chaff is blown off.