I just recently purchased my first two wheeler. After I bought it, I started looking for safety gear. While looking at riding jackets online I found a few airbag jackets.

The concept of a motorcycle airbag jacket (or vest) is fairly new. The only jackets that I found commercially available are:
Impact Jacket
HitAir
MotoAir
Airetronics

All four work on the same concept. The jackets contain an air bladder and CO2 cylinders. The jacket is tethered to the motorcycle. If the rider is ejected from the bike, the CO2 cartridges go off and fill up the air bladders. Hopefully cushioning your impact.

At first glance, they sounded like a great idea, but after I read a little more I began to have a few doubts. All four jackets are inflated when the tether to the bike is pulled. This means you have to actually separate from the motorcycle before the jacket will inflate. If the rider were to have a slide out (low side fall), the jacket would not begin to inflate until the rider had already hit the ground. Then after the rider separated from the bike, the jacket would be begin to inflate. So if you hit the ground while still being on the bike, the jacket won't inflate until after you have rolled away from the bike. This could help if you rolled on the ground and hit something after the initial impact. (curb, light post).

The second thing I noticed is the jackets are slow to inflate. The Motoair jacket takes up to 500 milliseconds to inflate. The others probably take a similar amount of time sense they all operate about the same way. This is relatively slow compared to a car air bag that inflates in about 170 milliseconds. Also, a car air bag triggers as soon as an impact is detected. With these jackets, you would have to crash and launch approximately two feet from the bike before the jacket would even start to inflate. That could be mean a significant amount of time passes between the bikes initial impact and when the air bag begins to inflate.

These shortcomings limit the scenarios that an airbag vest would be helpful.

Even with the drawbacks, there was a story in Pennsylvania of a rider being saved by his air bag jacket. Joseph McPhatter was wearing an "Impact Jacket" while riding on the interstate. He was hit by a car while travelling at free way speeds and reportedly went 100 feet through the air before hitting the ground. He walked away with only minor injures and no broken ribs. His accident seemed be the optimum scenario for an airbag jacket. He separated from the bike and went a good distance in the air before impact. This would have given the jacket plenty of time to inflate, so that when he did hit the ground, the jacket was fully inflated.

A more promising option, which is not yet for sale, is the the Dainese D-Air. Unlike the low tech jackets I previously mentioned, the D-Air is a very high tech jacket. It uses crash sensors instead of a mechanical tethering system. A small computer installed on the motorcycle uses a number of sensors to determine when you are crashing. When the computer senses a crash, it has the airbag inflate. So unlike with a tether, the jacket can inflate before you are ejected from the bike and even before your body has an impact.

In the above video, you can see that the jacket inflates before the rider hits the ground. The computer sensed that the bike was leaning too far and automatically inflated the jacket. If the rider had been wearing the Hitair, MotoAir or Impact Jackets, the jacket would not have begun to inflate until after the initial impact and probably wouldn't have finished inflating until after the rider rolled a few times.

The D-Air jacket is currently being used by some racers in Europe, but no plans have been announced for selling the jackets to the general public. If this jacket ever does come to market in the US, I may give it another look. Until then I will rely on my high vis FieldSheer Quatro jacket and the rider safety course I took.