BP oil spill trial continues as demonstrators note upcoming 3-year anniversary of disaster

The automatic mode function of the drilling rig's blowout preventer is intended to seal the well without rig personnel intervening when hydraulics, electricity and communications are all lost.

http://www.nola.com/news/gulf-oil-spill/index.ssf/2013/04/bp_oil_spill_draws_demonstrato.html