The following outfits appear in Flying too High:
Beige dress of mannish cut, dusty pink cloche, taupe shoes
I'd imagine that Phryne's flying garb would be similar to Amelia Earhart's one in the picture although perhaps every so slightly more stylish!
Red coat with astrakhan collar , black felt hat, Russian leather boots
Black skirt, white dolman sleeve blouse, red jersey top, black driving hat - Phryne's outfit purchased by Dot in Queenscliff.
Black velvet Erte dress with lapin cuffs and collar 6 inch band of fur on hem, Russian boots - Phryne's outfit for dinner with Dr Fielding