Dead reckoning

Posted by ESC February 24, 2000In reply to Dead reckoning posted by jeff waite on February 23, 2000

A phrase used in navigation when the pilot/captain is not using any navigation aids other than a map, clock, compass and speed indications, as compared to more modern devises like radio beacons or now GPS systems, etc.
Does any one know the origin?

"Dead" as an adverb means "absolutely, completely," according to The Barnhart Concise Dictionary of Etymology by Robert K. Barnhart. That's the only clue I could find.