Long-Running Underwater Robot Lost At Sea
this_boat_is_real writes "Somewhere off the coast of Chile a pioneering underwater robot named Abe lies in a watery grave today. The Autonomous Benthic Explorer was one of the first truly independent research submersibles, being both unmanned and un-tethered to its launching ship. While on its 222nd research dive on Friday all contact with the craft was lost, the Woods Hole Oceanographic Institution has announced."
Actually AC, I did read both the linked pages and neither says anything about the failsafe mechanisms.
But, I suppose that's not really consequential as long as you think you might have a pretext to spout something vitriolic.
"Prefiero morir de pie que vivir siempre arrodillado!"