An airbag assembly employs tape sensors to monitor the rate at which an airbag is deployed. The airbag is part of an airbag module that incorporates a vent that can be actuated if it is determined by logic associated with the airbag that the airbag has prematurely collided with an object. To better determine the dynamics of the airbag deployment, a sensor is positioned across a tear seam in the cover through which the airbag breaks. The sensor provides a direct indicator that the tear seam has opened, which is used as the starting time for monitoring the rate of airbag deployment. The tear seam sensor could also be used in conjunction with any airbag electronics to control a function of an airbag.