Jackets are an ideal garment for layering. Jackets do not take up much room and they protect your core. The core of your body is what all your blood circulates through, so keeping it warm is the most important thing you can do. Jackets work well when worn over most other clothing. You can wear them over sweaters, which can be worn over shirts, which can be worn over undershirts and thermals, so they're a perfect choice.
Navy flight jackets at LandingZone.com and other retailers are in many ways the best option for layering. Leather flight jackets preserve warmth very efficiently, and they're stylish, rather than fashionable. This means that they always look good, and they fit well with most other articles of clothing as long as you wear them well. This makes them a wonderful investment for any wardrobe, as they will complement whatever winter clothes you already have.