Subaru 2005 Legacy Owner's Manual page 119

Seat, seatbelt and SRS airbags
There are many types of collisions which might not
necessarily require SRS side airbag and SRS curtain
airbag deployment. In the event of accidents like those
illustrated, the SRS side airbag and SRS curtain air-
bag may not deploy depending on the level of accident
forces involved.
1-88
" Examples of the types of accidents in which the
SRS side airbag and SRS curtain airbag will ba-
sically not deploy.
A) The vehicle is involved in frontal collision with another
vehicle (moving or stationary).