Nothing beats the rugged look of a well-worn leather flight jacket. It normally takes years to make a new flight jacket into a soft, worn, scuffed jacket. You can speed up this process by several years over the course of a few weeks by deliberately wearing down the leather. For the best results, select a jacket that is made of cowhide or goatskin rather than lambskin leather. Lambskin is very delicate compared to other leathers and doesn't wear as well over time.
Compare your jacket to similar, older jackets that have become worn naturally. Jackets don't get worn evenly over time. Pay attention to the pockets, collar and cuffs to see the effect of human oils and daily handling. Look under the sleeves to see the effects of friction on the jacket. Note which areas have been worn more than others.
Walk in the rain while wearing your jacket. Don't stay in the rain too long, as you do not want to soak the jacket. The aim is to to get the outside of the leather moist. While it's still wet, bend your arms, bend over and move your arms in all directions. Wear your jack until it dries. The moisture will cause the leather to become more pliable, stretching in some places, shrinking in others, depending on the shape of your body and movement. If you can't wait for the rain, lightly mist your jacket with a spray bottle.
Rub the leather gently with steel wool to create wear in places like the cuffs, elbows and pockets. Rubbing it too little is always better than rubbing it too much. Use short strokes and do not create wear too evenly.
Roll up your jacket into a ball and toss it around to create a tough and tumble look. Sit on it while watching television. Put it under your mattress while sleeping. Any kind of stress or pressure will increase the wear of your flight jacket.
Put on your jacket as much as possible. There's no better way to create wear in your flight jacket than by constantly being dressed in it. Wearing a flight jacket 12 hours every day for two weeks is the equivalent amount of wear that the same jacket would get if worn only for a few hours every weekend for a whole year.