Preheat the air fryer to 350°F (175°C). In a large bowl, combine the ground turkey, crushed saltine crackers, minced onion, diced green bell pepper, minced garlic, milk, egg, 2 teaspoons ketchup, 2 teaspoons Worcestershire sauce, and ground black pepper. Mix just until combined to avoid toughness.
Form the mixture into a loaf roughly 6 inches long, 3–4 inches wide, and 2 inches tall. Sprinkle 3 tablespoons of brown sugar evenly on the bottom of the meatloaf.
Line the air fryer basket with parchment paper. Carefully place the loaf into the basket, sugar-side down. Air fry at 350°F (175°C) for 20 minutes.
While the meatloaf cooks, prepare the glaze: In a small bowl, whisk together 3 tablespoons ketchup, 3 tablespoons brown sugar, and 1 teaspoon Worcestershire sauce.
After 20 minutes, carefully remove the basket and brush the top and sides of the meatloaf with half of the prepared glaze. Return to the air fryer and cook for 5 more minutes.
Remove the meatloaf from the air fryer and brush with the remaining glaze. Let the meatloaf rest for 10 minutes before slicing to allow the juices to redistribute for maximum juiciness.