Lightly spray a 8x4-inch (20x10 cm) loaf pan with no-stick cooking spray.
Grate the onion into a large mixing bowl, then add the other ingredients and mix together (using your hands or a stand mixer) until well blended.
Preheat air fryer to 350°F/ 175°C
Press meat mixture into the prepared loaf pan, and smooth the top.
Air fry meatloaf for 45 minutes, until the meatloaf reaches an internal temperature of 160°F/ 72°C [Note 1] and is no longer pink in the center. [Note 2]
Let stand 10 minutes before serving.
Notes
Meatloaf made with ground beef should be cooked to 160°F/ 72°C. Meatloaf made with chicken or turkey (or other poultry) needs to be cooked to 165°F/ 74°C.
Check the internal temperature in the center of the meatloaf in a few places to ensure it is cooked the whole way through.