What is a Flak Jacket?

Mary McMahon
Mary McMahon

A flak jacket is a protective garment designed to worn over the torso, keeping the delicate internal organs and ribcage safe from harm on the battlefield. When well maintained, a flak jacket can protect the wearer from bullets, shrapnel, and other projectiles, except at very close range. An alternate spelling for the garment is flack jacket, with both spellings technically being considered correct. Flak jackets have largely been replaced by lightweight body armor, but they played a very important role in warfare for a portion of the twentieth century.

Kevlar® fabric, which is used to make flak jackets.
Kevlar® fabric, which is used to make flak jackets.

The garment was originally developed for members of the Royal Airforce by the Wilkinson Sword Company. Airmen were at risk of severe injury and death from Fliegerabwehrkanone, exploding shells fired from German anti-aircraft guns operated by ground-based military personnel. The shells were colloquially known as “flak,” and they could do severe damage to the unprotected torsos of pilots and crew as well as their aircraft.

A flak jacket.
A flak jacket.

Many people are familiar with the slang term “taking a lot of flak,” which is directly related to the German shells. On nights of heavy shelling, flak could make flying virtually impossible and highly dangerous. The sense of being overwhelmed by people from all sides firing shells transferred into the civilian world by way of many veterans. Unfortunately, a flak jacket to protect from metaphorical flak has not yet been developed.

To address the issue of literal flak, the Wilkinson Sword Company developed the flak jacket, a garment made from heavyweight material lined with metal plates. A flak jacket could also take the form of a flak vest, leaving the arms free for a better range of motion. The jackets proved to be useful, but extremely bulky. Other Allied troops adopted flak jackets for the crews of their aircraft, and ground based soldiers used them as protective wear as well. Many soldiers were saved from death and serious injury by their flak jackets during the Second World War, along with conflicts around the world afterwards. For many nations, a flak jacket was standard issue for soldiers, along with other basic supplies.

The widespread adoption of Kevlar® and more lightweight protective plate materials led to the production of sturdy but much lighter body armor. The term “flak jacket” is sometimes used to refer to modern body armor, which is made by an assortment of companies. The steel plates and bulky materials of the old fashioned flak jacket, however, are not in use on the modern battlefield, although many veterans saved their flak jackets to commemorate their experiences.

Flak jackets may be used to provide protection from bullets.
Flak jackets may be used to provide protection from bullets.
Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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Discussion Comments


@pleats: Oakley Flaks are called that because of the lenses are strong enough to protect the eyes from high velocity impacts and not just in the flak line, but all their lenses. I use my flaks for shooting, plus I have several friends deployed in the sandbox who wear them.


So explain this to me -- I saw some Oakley flak jacket sunglasses, and I wasn't sure what a flak jacket was, so I looked it up here.

But now I'm even more confused. What do the sunglasses have to do with a flak jacket? They're not even military-style sunglasses, as far as I know.

Is it just a marketing thing, a cool name, or is there some reason that the Oakley sunglasses are being marketed as "flak jacket" sunglasses? I am so curious about this now!


Do you know how effective those jackets are? I'm interested in how well both the Kevlar flak jackets and the old military flak jackets worked.

I had heard somewhere that a lot of the stuff that you see in the military movies -- people being shot point blank and surviving because of a flak jacket or vest, etc. -- are really exaggerated. So how well do those things actually work?

I'm sure they have to be pretty OK since the military still uses them, but I was just curious about what kinds of things it could stand up to. Bullets, shrapnel, mine fragments, that kind of thing.

Does anybody have any idea?


My dad has an old military flak jacket that he keeps from his time in the service. One thing that you never realize is how heavy those things are!

Of course, his is back from before the Kevlar flak jackets were invented, so I don't know if they're still that heavy, but it just really makes you think about how hard all the little things about being a soldier can be.

I mean, having to drag that thing around plus your pack and gun and whatever else you have to carry as a soldier -- I guess it just gives me a new respect for all the things that soldiers go through.

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