For the last time, please! AA is American Airlines!
Air Asia is AK.
Even though AAX is loosely used for Air Asia Express, it is not official, unsanctioned. M'sia boleh crap. I take the liberty of assigning Express for X in AAX since it is a " carry on " from FlyAsianXpress, as express in " modern aviation lingo " means " low cost "
The three letter code AAX is for Araxa airport in Brazil. Comprende?