Operation

In advanced frontal air bag systems, the electronic control unit utilizes additional data input to determine with what level of power, and even IF, the driver frontal air bag or passenger frontal air bag will inflate.

Advanced air bag deployment determinations are based on the system's design and sensor inputs, which typically include:

• Size or weight of an occupant
• Whether the occupant is wearing a seat belt
• How far back the occupant's seat track is set
• Severity of the crash

Please see Frontal Air Bags - Cautions for more on advanced frontal air bags.

As of 2008, advanced frontal air bag systems in the U.S. vehicle fleet include systems that use:

• All-suppression strategies
• A combination of suppression and low-risk deployment strategies
• All low-risk deployment strategies

Systems using suppression strategies are tested for air bag activation using a dummy that weighs approximately 108 lbs. However, consumers should be aware that specific weight settings for suppression-based air bag systems may vary.

It's also important for consumers to keep in mind that proper operation of some advanced frontal air bag systems is highly dependent on the pressure (also known as "loading") placed on the seat bottom by the occupant - and that a number of situations can result in occupant misclassification. For more on this subject, see: What should I do when the "PASS AIR BAG OFF" indicator light does not give me the expected result? )

Additional technologies are becoming available to help advanced frontal air bag systems more accurately classify vehicle occupants. These include pattern recognition, optical, infrared, ultrasonic, and electric field sensor technologies.

Background

All passenger cars and light trucks produced after September 1, 2006, are required to have advanced frontal air bags. The advanced air bag rule (as part of Federal Motor Vehicle Safety Standard No. 208) applies to all classes of vehicles - passenger cars and light trucks, such as pickups, SUVs and vans - that have a gross vehicle weight rating (GVWR)* of 8,500 pounds or less and an unloaded vehicle weight of 5,500 pounds or less.

• First generation frontal air bags saved thousands of lives, but were also responsible for injuring or killing some vehicle occupants (especially infants and children) who were unrestrained or positioned too close to air bags as they were inflating. "Too close" can occur when an occupant, typically unbelted or leaning out of position, slides forward just before the crash impact (the period known as pre-crash braking) to within a few inches of - or directly on top of - a rapidly inflating air bag.
• Second generation or "depowered" air bags were designed to help prevent these air bag-related injuries and deaths, generally by inflating with less energy or power and volume.
• Third generation or "advanced" frontal air bags utilize sophisticated sensing devices to be even more effective than depowered air bags in saving lives - while at the same time reducing the potential of causing an air bag-induced serious injury or death to a child or small-stature adult.

The GVWR is the weight of the empty vehicle plus the maximum weight of cargo and passengers that can be safely loaded in the vehicle, as specified by the manufacturer. The label indicating GVWR is usually located on the driver's door jamb or door.

Safety Benefits

Like first and second generation frontal air bags, third generation advanced frontal air bags inflate in a fraction of a second to prevent occupants from striking the interior of the vehicle during a moderate to severe crash.

However, in a lower-speed frontal crash, where full-force air bag deployment would not be necessary or could cause injury to smaller occupants, an advanced air bag system provides the appropriate level of protection by:

• Inflating a frontal air bag with less force (referred to as low-risk deployment), or
• Shutting off a frontal air bag entirely (referred to as suppression.)

Cautions

Advanced frontal air bags can help lessen the risk of air bag-related injuries and fatalities. However, even if your vehicle is equipped with this type of air bag restraint system, NHTSA still recommends that you:

• Always wear your seat belt. Advanced frontal air bags are a supplemental restraint system, just like earlier generation air bags, and must be used in combination with a seat belt. All occupants should wear a seat belt or be seated in an appropriate child safety restraint system - every trip, every time.
• Place children under 13 in the rear seat. Parents and caregivers should always place children under 13 in the rear seat in an appropriate child safety restraint system. The rear seat is the safest place for children. For additional information on child safety restraint systems, see 4 Steps for Kids.
• Read your vehicle owner's manual. No air bags - even advanced frontal air bags - can be designed to handle every situation. Air bags can still cause serious injury or death to occupants who are not properly restrained and in the proper seating position. Read your owner's manual to understand the operation of your vehicle's air bag system, and take all precautions necessary to ensure you maximize air bag protection while minimizing risks.

Consumer info Requirements

Vehicles with advanced frontal air bags are required to have warning labels with the phrase "EVEN WITH ADVANCED AIR BAGS" on the sun visors for both the driver and passenger seating positions.

Vehicles with advanced frontal air bags that are designed to suppress the air bags (not deploy them) are also required to have a "PASS AIR BAG OFF" (or PASSENGER AIR BAG OFF) indicator light. Although not required by law, some manufacturers may also provide a “PASS AIR BAG ON” indicator light next to the "PASS AIR BAG OFF" indicator light for greater status recognition.

When illuminated, the purpose of the "PASS AIR BAG OFF" indicator light is to inform you that the passenger frontal air bag has been automatically turned off (suppressed) by the advanced frontal air bag system and therefore will not deploy. This can happen if sensors detect a small-stature passenger, such as an infant or child, in the right front passenger seating position.

The location of the "PASS AIR BAG OFF" indicator light will vary depending on the design of the individual vehicle. Manufacturers are required to place this indicator light in a position that is both visible and recognizable to the driver and right front passenger under all driving conditions, typically on the dashboard center or on the rearview mirror.

Note: The "PASS AIR BAG OFF" indicator light is different than the "air bag readiness indicator light" located in the driver's side instrumental panel. The air bag readiness indicator light illuminates or flashes when the air bag diagnostic system detects a fault in your vehicle's air bag system, such as a component failure, informing you that service is immediately required.

Vehicle manufacturers are also required to provide detailed information in the owner's manual about the features of a vehicle's advanced frontal air bag system and how it operates.