As a long time Baltimorean, we woke up to some tragic news this morning. The Francis Scott Key bridge, which spans the only way in and out of the Port of Baltimore was struck by a container ship and collapsed. It will take awhile to sort out the ramifications of this incident, but we already know of lost lives, port closure, and serious gnarling of road traffic. I have always been fascinated to read commercial captains' posts on ScubaBoard, so I'm wondering what are the possible scenarios where something like this could happen? Aren't large container vessels of this type equipped with multiple redundant navigation systems that prevent collision with known fixed obstacles? Can these even be overridden manually? There's a good summary of the accident here: Baltimore Francis Scott Key Bridge collapse: What we know about ship and bridge . The article seems to suggest the vessel left port, lost power, and drifted into the bridge support structures. Does this seem like a feasible scenario? I'm looking forward to hearing from people who actually know something about how large shipping vessels operate.