Frontal air bags have come a long way since they first appeared in the 1980s. Although those older air bags saved thousands of lives, they deployed the same way for every occupant, causing injury and in some rare cases even death to children, small adults, and any unbelted occupants who were positioned too close to the air bag as it deployed. Today's advanced frontal air bags, which first came out in some 2004 models, are better able to protect drivers and front seat passengers by using sophisticated sensing systems to determine whether, when and how much to deploy.
But here's the catch: Even though air bags have come a long way, advanced frontal air bags cannot take the place of wearing your seat belt. This is why air bags are called a "supplemental restraint system." They are your second line of protection AFTER the seat belt - one of many reasons it's important to understand how advanced air bags function and why they work the way they do.
TRAFFIC SAFETY FACT: From 1987 to 2012, there were an estimated 39,976 lives saved by frontal air bags.
Advanced frontal air bags use sophisticated sensing devices to provide the right level of protection to drivers and front seat passengers in the event of a crash. The "brain" of the air bag is its electronic control unit (ECU), which receives signals from various sensors and then decides if, when and how each air bag should deploy. The ECU will decide what deployment level is best, depending on the occupant's weight, seating position, seat track position and seat belt use, as well as the severity of the crash. When appropriate, it may signal the frontal air bag(s) to shut off entirely (referred to as "suppression").
Your advanced frontal air bag is not intended to deploy in all crashes - even frontal crashes - especially when deployment may cause more harm than good or if the seat belts will provide enough protection on their own. The way an advanced frontal air bag deploys in a crash depends not only on the occupant factors mentioned above, but on several other key factors, such as your vehicle's speed, the type of impact, impact direction, the air bag system's particular design strategy, and the crash sensor locations.
During moderate-to-severe frontal crashes, an advanced frontal air bag fully inflates in a fraction of a second to prevent you from hitting the interior of your vehicle. However, in lower-speed frontal crashes, where full-force air bag deployment would be unnecessary or could cause injury to smaller occupants, an advanced frontal air bag system inflates at less than 100% to provide optimum protection or deployment is suppressed altogether. In the event of a rollover, side-impact, or rear-end crash, advanced frontal air bags are typically not designed to offer protection and may not even deploy.
Advanced frontal air bags are smart when it comes to sensing your weight, seat position and other factors but, again, they are intended to enhance—not replace—the protection of your seat belt! The same goes for front seat passengers. Seat belts are your first line of defense during a crash, whereas air bags are a supplemental restraint system. Remember, it takes two: First your seat belt, then your air bag. Always buckle up before turning on the ignition, and make sure your front passenger is buckled up, too. Read more about how air bags function in general.