I took a close look at my little toaster oven this evening (it sounds like these air fryer devices are simply smaller convection ovens). I baked chicken thighs on the low rack but wanted to brown them a bit on top so switched to broiler and realized the oven only runs the fan during the bake operation. When broiling I think the fan running would mean less chance of scorching if you're not careful. If that is the way the air fryer operates I can see why they are popular.