Whisk together the brown sugar, onion powder, garlic powder, chili powder, smoked paprika, ground cayenne, salt and pepper in a small bowl.
Pat the salmon fillets dry with paper towels and drizzle each fillet with a paper towel. Season the fish with the seasoning mixture and set aside.
Arrange the salmon in the basket of an air fryer and air fry for 7-9 minutes depending on the thickness of the salmon (cooking times may vary depending on the model of your air fryer.)
Open the air fryer and check for doneness with either an instant read thermometer or a fork. The fish will flake easily with a fork when done.
Cook for an additional 1-2 minutes, if necessary.
Serve the salmon with tartar sauce or garlic butter sauce, if desired.