IPA: /ˈɛərwərd/
KK: /ˈɛrˌwɔrd/
In a direction toward the sky or upward.
The bird flew airward, soaring high above the trees.
Airward is formed from "air" (from Old English "aer", meaning the atmosphere or sky) and "-ward" (meaning in the direction of). The word "airward" means in the direction of the air or sky.
Think of moving 'in the direction of' ('-ward') the 'atmosphere' ('air') — that's why airward means towards the air.