Grease a loaf pan with cooking spray. Set aside.
In a bowl, mix together the flour and bicarbonate of soda.
In another bowl, add the butter and sugar and beat until pale and fluffy.
Add the eggs, one at a time along with a little flour and mix well.
Stir in the remaining flour and walnuts.
Now add the bananas and mix until well combined.
Place the mixture into the prepared loaf pan evenly.
Slide the Air Fryer Basket inside and adjust the temperature to 355 °F to preheat for 5 minutes.
After preheating, arrange the loaf pan into the Air Fryer Basket.
Slide the basket into Air Fryer and set the time for 10 minutes.
After 10 minutes of cooking, adjust the temperature to 340 °F for 15 minutes or until a toothpick inserted in the center comes out clean.
After cooking time is finished, remove the cake pan from Air Fryer and place onto a wire rack for about 10 minutes.
Carefully remove the bread from pan and place onto the wire rack to cool completely before slicing.
Cut the bread into desired-sizes slices and serve.