Resources > Terminology

Aggressive air bags - those air bag systems that deploy too forcefully and therefore have a tendency to cause unnecessary injuries.

Air bag inflator - a device installed within an air bag module that generates the gas used to pressurize the fabric air bag.

Air bag sensors - electrical and/or electro-mechanical switches that determine whether a crash is severe enough to deploy the air bags.

Automatic seat belts - seat belts that automatically position themselves around a consumer without requiring the consumer to take any action, such as seat belts that slide in a track along the door; also known as passive seat belts.

Bag slap - a high speed whipping contact between a deploying air bag and an occupant that causes intense, localized injuries such as blindness or facial injuries.

Black box - an informal name given to a computer within the vehicle that can diagnose electrical faults within the air bag system, and record pre-crash or crash information.  A black box can also be known by an acronym such as EDR (Event Data Recorder), SDM (Sensing and Diagnostic Module), RCM (Restraints Control Module), ECU (Electronic Control Unit), DERM (Diagnostic and Energy Reserve Module), etc.

Clockspring - an electro-mechanical device mounted at the top of the steering column, beneath the steering wheel, that allows an electrical signal to be transmitted to the driver air bag module while permitting the steering wheel to turn.

Crash sensor - a sensor that detects the deceleration of the vehicle to determine whether and when to deploy the air bags.  These are often mounted inside the vehicle, but many better systems also sensors near the front of the vehicle.

Crashworthiness - the ability of a motor vehicle to reasonably protect its occupants when the vehicle is involved in an accident.

Deployment thresholds - the crash severity required for deployment of the air bags. The “no-fire” threshold is the crash severity at which the air bags should never deploy, the “all-fire” threshold is the crash severity at which the air bags should always deploy, and between them is the “gray zone” in which the air bags may or may not deploy.

Dual-stage inflators - air bag inflators that inflate the air bag with a lower level of pressure in lower speed accidents and a higher level of pressure in higher speed accidents; they were first used in production vehicles in 1973.

Energy management loops - loops of stitched seat belt webbing that are intended to tear open during a crash; they may lower certain injury numbers in very limited test circumstances, but they greatly reduce the protective effect of the seat belt in real-world accidents. They are also sometimes known as energy absorbing loops.

Enhanced injuries - the additional injuries suffered by consumers when a vehicle is not crashworthy, such as when the vehicle’s safety systems are defective.

False latching - occurs when a seat belt appears to be properly buckled when in fact it is not, allowing the seat belt to come loose during an accident.

Federal Motor Vehicle Safety Standards - regulations published by the U.S. National Highway Traffic Safety Administration relating to motor vehicle safety.

Inadvertent deployment - air bag deployments that are not justified, such as those occurring in very minor accidents or even when the vehicle is not involved in an accident.

Inadvertent unlatching - unintended unbuckling of the seat belt, so that it is no longer capable of providing reasonable protection to the consumer.

Inertial unlatching - unbuckling of the seat belt that occurs due to rapid localized acceleration such as that sometimes observed in side impacts.

Late deployment - air bag deployment that occurs late in the accident sequence, when the consumers are dangerously close to the air bags.

Multi-stage inflators - air bag inflators whose inflation pressure is adjustable depending on the severity of the accident.

Out-of-position - when a consumer is no longer in the standard seating position, but is close to the air bags.

Passive seat belts - seat belts that automatically position themselves around a consumer without requiring the consumer to take any action, such as seat belts that slide in a track along the door; also known as automatic seat belts.

Safety cage - the portion of the vehicle containing the passenger compartment; it is intended to strongly resist penetration during an accident so as to protect consumers.

Seat belt anchors - the end attachment points of the seat belt.

Seat ramp - a device installed under a seat that helps prevent a consumer’s pelvis from sliding under the lap belt portion of the seat belt system.

Submarining - occurs when a consumer slides beneath the lap belt portion of the seat belt system, allowing the lap belt to exert force against the abdomen, often causing devastating internal injuries.

Tethers - internal pieces of fabric that connect the front and back sides of the air bag on the inside; they guide the air bag while it is deploying (before the bag is filled), and help reduce injuries to consumers from the air bag.

Vehicle aggressivity - the imbalance that exists when a large, heavy vehicle strikes a smaller, lighter vehicle, often resulting in devastating injuries to consumers in the smaller vehicle.