I was a Navy pilot in single seat aircraft. Maybe my experience colors my opinion. I have flown on many single-piloted scheduled airline aircraft and felt them to be just as safe a two-persyn [sic] cockpit. I'm not even sure what the second aircrew member does on most flights. only one pilot flies each leg. Handel the radios? Fill in the flightlogs?

You could convince me that a second crew helps in an emergency, but cockpit recordings of emergency checklists can do the same thing. The captain always takes sole control, anyway. Can locomotives be any different?