You still have to trigger it when you get caught in the slide (pull cord like thing if I remember correctly).

In the end, (IMO), the first thing is to pay attention to terrain and avoid dangerous situations. Realizing that it is impossible to have 0 avalanche danger in slide prone terrain, you (and the people with you) better carry beacon/shovel/probe, and everybody needs to be johnny on the spot with them.

The airbag and avalung are nice, and will/have save lives, but they are not at all a replacement for the above.