[Question] Yasuo's Ult and Airborne Champions

Champion: Yasuo Enemy: Tristana {{champion:157}} Yasuo is level 6, with ult ready. {{champion:18}} Tristana launches herself into the air and attacks Yasuo. Question: Why can't Yasuo use his ultimate on Tristana when she herself made herself Airborne? Reason for Question: I recently tried this in NA servers, and I believe Tristana should be considered **AIRBORNE** when she launches herself in the air. However no marker shows that I can activate Yasuo's Ult. Possible Champions that can be considered Airborne: Corki, Ziggs, Tristana, Garen, Aatrox. EDIT: I am considering any champion that can be in mid-air, even for a split second.
Report as:
Offensive Spam Harassment Incorrect Board