The term "ded reckoning" (or "dead reckoning," if you prefer) first appeared in the 1600s.
Pilots often get nervous with ded reckoning. To do it correctly, we must use a plotter and measure our true course on a chart.
We (the photographer and me) decided to plan a flight that would be at least an hour in length, would not depend to any great extent on electronic navigation, and would allow us to exercise both our ded reckoning and pilotage skills.
Winds and temperatures aloft are the elixir we need to really perform the ded reckoning magic.