GMC 2008 Acadia - Manual (Page 72)

Seat-mounted side impact airbags are not intended to
inflate in frontal impacts, near-frontal impacts, rollovers,
or rear impacts. Roof-rail airbags are not intended to
inflate in rear impacts. A seat-mounted side impact
airbag is intended to deploy on the side of the vehicle
that is struck. Both roof-rail airbags will deploy when
either side of the vehicle is struck, or if the sensing
system predicts that the vehicle is about to roll over, or
in a severe frontal impact.
In any particular crash, no one can say whether an
airbag should have inflated simply because of the
damage to a vehicle or because of what the repair costs
were. For frontal airbags, inflation is determined by
what the vehicle hits, the angle of the impact, and how
quickly the vehicle slows down. For seat-mounted
side impact and roof-rail airbags, deployment is
determined by the location and severity of the side
impact. In a rollover event, roof-rail airbag deployment is
determined by the direction of the roll.
What Makes an Airbag Inflate?
In a deployment event, the sensing system sends an
electrical signal triggering a release of gas from
the inflator. Gas from the inflator fills the airbag causing
the bag to break out of the cover and deploy. The
inflator, the airbag, and related hardware are all part of
the airbag module.
Frontal airbag modules are located inside the steering
wheel and instrument panel. For vehicles with
seat-mounted side impact airbags, there are airbag
modules in the side of the front seatbacks closest to the
door. For vehicles with roof-rail airbags, there are
airbag modules in the ceiling of the vehicle, near the
side windows that have occupant seating positions.
How Does an Airbag Restrain?
In moderate to severe frontal or near frontal collisions,
even belted occupants can contact the steering wheel or
the instrument panel. In moderate to severe side
collisions, even belted occupants can contact the inside
of the vehicle.
Airbags supplement the protection provided by safety
belts.
Frontal airbags distribute the force of the impact more
evenly over the occupant’s upper body, stopping
the occupant more gradually. Seat-mounted side impact
and roof-rail airbags distribute the force of the impact
more evenly over the occupant’s upper body.
Rollover capable roof-rail airbags are designed to help
contain the head and chest of occupants in the
outboard seating positions in the first, second, and third
rows. The rollover capable roof-rail airbags are
designed to help reduce the risk of full or partial ejection
in rollover events, although no system can prevent all
such ejections.
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