Mitsubishi LANCER Owner's Manual page 87

Seat and restraint systems
The side airbag and curtain airbag MAY NOT
DEPLOY when ...
In certain types of side collisions, the side airbag and curtain
airbag may not deploy, even if the deformation of the body
seems to be large, because the vehicle's body structure is
designed to absorb the impact and to deform in order to help
protect the occupants. Some typical situations where the side
airbag and curtain airbag may not deploy are shown in the
illustrations.
2
Because the side airbags and curtain airbags do not protect the
occupant in all types of side collisions, be sure to always wear
your seat belts properly.
2-56
Side impact in an area away from the passenger compartment
Motorcycle or other similar small vehicle collision with the
side of vehicle
Collision with a utility pole, tree or other narrow object