2-32 Seats and Restraints
Seat-mounted side impact and
roof-rail airbags are intended to
inflate in moderate to severe side
crashes. In addition, these roof-rail
airbags are intended to inflate
during a rollover or in a severe
frontal impact. Seat-mounted side
impact and roof-rail airbags will
inflate if the crash severity is above
the system's designed threshold
level. The threshold level can vary
with specific vehicle design.
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.