Peel and cut the onion crosswise into 3/4 inch slices, then separate into rings.
Set up for dredging: Place flour in a shallow dish. Combine beaten eggs and water in a second shallow dish. Place breadcrumbs in a third shallow dish. Divide the garlic salt, seasoned salt and cayenne evenly across the 3 bowls and stir each to combine.
Dredge onions as follows: 1) egg mixture, 2) flour mixture, 3) egg mixture, 4) flour mixture, 5) egg mixture, 6) breadcrumbs, pressing crumbs firmly on all sides.
(Optional for easier handling) Place coated onions in a shallow tray and place in the freezer for 30 minutes.
Place the cooking tray on the bottom of the air fry basket. Using the display panel, select AIR FRY, then adjust the temperature to 400°F and the time to 10 minutes, then touch START.
When the display indicates “Add Food” place onion rings in a single layer on the cooking tray (you may need to work in batches).
When the display indicates “Turn Food” turn the onion rings over.
When the Air Fry program is complete, remove the onion rings. Serve hot.