Subaru 2001 Impreza Owner's Manual page 93

n Examples of the types of accidents in which the SRS airbag
will basically not deploy.
The SRS airbag is basically not designed to deploy if the vehicle is
struck from side or from behind, or if it rolls onto its side or roof, or if it
is involved in a low-speed frontal collision.
The vehicle is struck from
behind.
In an accident where the vehicle is impacted more than once, the
SRS airbag deploys only once on the first impact.
Example: In the case of a double collision, first with another vehicle,
then against a concrete wall in immediate succession, the SRS airbag
is activated on the first impact but not on the second.
2-36
The vehicle is struck from
the side.
HG0291
The vehicle rolls onto its
side or roof.
HG0292 HG0293
HB1070BB