Page 6 from 11
Since air bags inflate with considerable speed and force, you can be injured by an air bag,
especially if you are unbelted, out of position or too close to a deploying air bag. With
respect to front air bags, the proper seating position is as far away as possible from the
air bag (consistent with proper operation of vehicle controls for the d\
river) and with the
occupant’s back against the seat backrest, which should be in a nearly upright position.
With respect to door mounted side air bags, occupants should avoid leaning against the
vehicle’s door, and should never allow children to do so. Please see operator’s manual
and labels in the vehicle for further information about children and air bags and use of
Criteria for an ETD / air bag deployment.
In order to determine whether to deploy, an electronic control unit evaluates the intensity,
duration and direction of the vehicle deceleration or acceleration durin\
g the very earliest
phase of the collision. The deployment thresholds are variable and are adapted in
response to the intensity of the vehicle acceleration or deceleration rate sensed early in
the collision. To be able to protect occupants who begin moving during the early portion
of a crash sequence, the system’s determination whether to deploy an ETD(s) and / or air
bag(s) must be anticipatory since deployment has to happen very early in the collision.
Vehicle deceleration or acceleration
rate and impact force direction are
determined based on the force
distribution, the collision angle, the
deformation characteristics of the
vehicle and the state, mass and
deformability of the object with which
the vehicle collides.
Vehicle damage is neither a determinative factor for an ETD / air bag deployment nor an
indication that an ETD / air bag should have been deployed. This means \
that even if a
vehicle appears severely damaged in an accident, an ETD / air bag deployment threshold
is not necessarily met. An impact may be of a type that results in substantial damage to
the vehicle but does not involve stiff structural parts, thus resulting in a deceleration rate
below the system deployment threshold. Conversely, air bags can deploy even if the
vehicle damage in an accident is relatively slight. Thus, a lower speed collision involving
relatively stiff vehicle structures may reach the deceleration threshold for deploying an
ETD / air bag. Furthermore, the vehicle speed at the start of the collision and the injuries
suffered during a collision do not indicate whether an air bag should have deployed, since
the severity of the load to and physical injuries experienced by occupants often depend
on the type of collision, the deformation characteristics of the object involved in the
collision, and the overall severity of the collision.
Page 7 from 11
Front Supplemental Restraint System deployment logic.
If the seat belt is worn by a front seat occupant, only the emergency tensioning device for
that seat belt is deployed in an impact generating a frontal longitudinal deceleration rate
meeting the system’s first deployment threshold. The respective front air bag is only
deployed in addition to the ETD if a second, higher deployment threshold is met. If the
seat belt is not worn by a front seat occupant, then the risk of injury from a deploying air
bag is much greater than for a belted occupant. Never rely on the presen\
ce of an air bag
to avoid wearing your seat belt.
Driver and front passenger air bags.
The driver’s front air bag is located in the center of the steering wheel, and the front
passenger air bag is housed above the glove compartment (or in place of\
compartment in older models). They can be recognized by the "SRS" or "SRS AIRBAG" or
“AIRBAG” lettering. Driver and passenger front air bags are designed primarily to help
reduce the risk and/or severity of contact between the seat-belted driver’s and front
passenger’s head and chest and the interior components in front of th\
em. The driver
front air bag inflates in front of the steering wheel. The passenger front air bag inflates in
front of and above the glove compartment.
Driver and/or front passenger air bags are deployed in an accident gener\
longitudinal vehicle deceleration rate meeting the system’s deployment thresholds
sensed early in the collision. The front air bag deployment can differ depending on seat
In vehicles equipped with a BabySmart™ air bag deactivation system (recognized by the
BabySmart™ label on the right front door by the instrument panel), the front passenger
air bag is only enabled and thus capable of deploying if the PASSENGER AIR BAG OFF
indicator lamp is not lit. When the indicator lamp in these vehicles is off, the system
does not recognize that a BabySmart™ child seat is installed on the front passenger seat.
When the indicator lamp in these vehicles is lit, the system does recognize a
BabySmart™ child seat in use, and the passenger front air bag will not deploy. In
vehicles equipped with an occupancy sensor for the front passenger seat, the front
passenger air bag is only enabled and thus capable of deploying if the s\
ensor detects a
certain minimum weight on the seat, or if the seat belt buckle is fastened.
Note: Vehicles equipped with an occupant classification system are not equipped with
the BabySMART™ system.
Page 8 from 11
A front air bag will not be deployed in a lateral rollover unless the ro\
llover also generates
a longitudinal deceleration rate meeting the system’s deployment threshold sensed early
in the collision.
Special features of dual-stage front air bags.
If the vehicle is equipped with dual-stage front air bags, the front air bag is initially
inflated with a single inflator when a first activation threshold is reached. If a second
threshold is reached, within the few milliseconds in which the determination to deploy is
made, a second inflator provides additional inflation to increase the inflation rate of the
air bag to help address the higher deceleration rate sensed with respect to the accident.
If the vehicle is equipped with a front passenger weight classification system, the body
weight of the front passenger is taken into account along with the accident severity and
the seat belt status when calculating the air bag inflation rate.
Knee air bags supplement the function of the knee bolster in head-on collisions that
exceed the deployment threshold.
Special features of an Occupant Classification System.
If your vehicle is equipped with an Occupant Classification System (OCS), it automatically
turns the passenger front air bag on or off based on the classified occupant size category,
determined by weight sensor readings from the front passenger seat.
The system is not designed to deactivate a side impact air bag or window curtain air bag.
If OCS classified the occupant sitting in the front passenger seat as an adult, the
passenger front air bag will be enabled and deploy in an accident meetin\
g the respective
air bag deployment criteria. If OCS classified the front passenger seat occupant as a small
occupant, depending on weight, the passenger front air bag may or may not be enabled.
The passenger front air bag will be disabled and the PASS AIR BAGOFF ind\
icator lamp is
lit, if the system:
• classified the front passenger seat occupant as child-sized at a certain weight level or
• classified the front passenger seat as empty.
In order for OCS to classify the front seat passenger as it is intended to operate, the front
passenger seat occupant must always be seated and belted properly (seat\
upright, back against the seatback and feet on the floor). In addition, any circumstance
that results in the system misreading the passenger seat occupant’s correct weight
category must be avoided (for example transferring the passenger weight to the armrest
by leaning on it, attaching objects to the seatback or putting items under, on or around
the seat or seat back). You need to make sure that the passenger front seat has clearance
in all directions at all times. Otherwise the OCS may not be able to properly approximate
Page 9 from 11
the occupant’s size category, which could cause the system to activate the passenger
front air bag even though it should have been deactivated, or vice versa.
Use the PASS AIR BAG OFF indicator lamp to determine whether the passenger front air
bag is deactivated. The PASS AIR BAG OFF indicator lamp will illuminate after the
ignition is turned on. It will continue to illuminate if the front passenger seat is
On vehicles equipped with OCS, deactivation of the passenger front air bag can occur as a
result of various factors, such as an empty seat or an occupant who does not meet a
certain minimum weight, or foreign objects interfering with the system.
Demonstration of available airbags in the M-Class (W 163). The accident-specific
circumstances determine which airbag(s), if any, will deploy.
Side impact air bags.
A side impact air bag is designed to help further protect the thorax(that is, upper body,
but not the head, neck or arms) of the occupant sitting on the impacted side of the vehicle
in a collision generating a lateral (sideways) vehicle acceleration / deceleration rate
meeting the system’s deployment threshold sensed early in the collision. In such cases,
the side impact air bag deploys in the area of the door below the side w\
mounted side impact air bag) or directly next to the affected seat (seat backrest mounted
side air bag). Side impact air bag installation positions vary depending on the vehicle
model. See the operator’s manual for further details.
The lateral acceleration / deceleration rate required to deploy the side impact air bag
must be sensed by the system even earlier in the accident sequence for side-impact
collisions than for frontal collisions, as the distance between the occu\
pant and the object
involved is much smaller in the side-impact collisions. Side impact air bags are designed
Page 10 from 11
• in an accident generating a lateral (that is, sideways) vehicle deceleration /
acceleration rate meeting the system’s deployment threshold sensed early in the
• on the side of the vehicle receiving the impact;
• independent of the deployment of front air bags or ETDs (if also deploy\
ed as a result
of the forces generated by the accident).
In vehicles equipped with an occupancy sensor for the front passenger se\
at, the front
passenger side impact air bag is only enabled, and thus capable of deploying, if the
occupancy sensor detects a certain minimum weight in the seat or if the seat belt buckle
is fastened. However, the side impact air bag on the passenger side will still deploy in
circumstances calling for deployment even if the PASSENGER AIR BAG OFF indicator
lamp is lit. Side impact air bags will not deploy in lateral rollovers unless and until the
rollover generates a lateral vehicle deceleration or acceleration rate meeting the system’s
Head protection systems.
Your vehicle may be equipped with either window curtain air bags(installed in the roof
frame in sedans, station wagons and light trucks)or head-thorax side air bags (with a
larger air bag area than the side impact air bag and designed to reach the occupant’s
head) installed in the seat backs of convertibles.
Window curtain air bags.
Your Mercedes-Benz vehicle may be equipped with window curtain air bags (as optional
or standard equipment, typically in sedans or coupes but not in convertibles) that are
designed to help increase head protection for the occupant sitting on the impacted side of
the vehicle where the system’s deployment threshold has been met. The window curtain
air bag deploys in the area of the side windows. Window curtain air bags are deployed:
• in an accident generating a lateral vehicle deceleration / acceleration rate meeting the
system’s deployment threshold sensed early in the collision,
• on the side of the vehicle receiving the impact,
• independently of the deployment of front air bags or ETDs (if also acti\
vated as a result
of the forces generated by the accident).
In vehicles with a BabySmart™ air bag deactivation system (recognized by the
BabySmart™ label on the right front door by the instrument panel), the window curtain
air bag on the passenger side will remain enabled and thus capable of de\
circumstances calling for deployment even if the PASSENGER AIR BAG OFF indicator
lamp is lit due to the proper installation of a BabySmart™ child seat. Similarly, in vehicles
equipped with OCS, the system does not disable the window curtain air bags when it
disables the passenger front air bag.
In vehicles with rollover sensors, window curtain air bags are designed to deploy in
lateral rollovers meeting certain pre-set parameters. In that circumstance, window curtain
air bags will be activated on both sides of the vehicle.