In a large bowl, combine 1 1/2 pounds lean ground turkey, 2/3 cup breadcrumbs, 1/2 medium yellow onion, minced, 1 clove garlic, minced, 1/2 cup milk, 1 large egg, 2 teaspoons ketchup, 2 teaspoons Worchestershire sauce, 1/2 teaspoon Kosher salt, and 1/2 teaspoon ground black pepper. Mix until all the ingredients are evenly distributed.
Form the mixture into a loaf about 6 inches long, 3-4 inches wide, and 2 inches tall. Add the 3 Tablespoons light packed brown sugar to the bottom of the loaf. Prepare the air fryer basket with a piece of parchment paper and place the formed meatloaf onto the parchment paper.
Air fry the turkey meatloaf at 350°F (177°C) for 20 minutes. While the meatloaf is cooking, prepare the glaze by mixing 2/3 cup ketchup, 2 Tablespoons light packed brown sugar, and 1 teaspon Worchestershire sauce in a bowl.
After the first 20 minutes of cooking, brush the meatloaf with half of the glaze, then return to the air fryer for another 5 minutes at 350°F (177°C).
Once done, glaze the meatloaf with the remaining mixture and let it rest for 10 minutes before slicing.