Definition
A method of navigation that determines an aircraft's current position by calculating from a known starting point using the aircraft's heading, true airspeed, ground speed, wind, and elapsed time, without reference to external landmarks or radio aids.
Plain English
Working out where you are right now by starting from a known spot and tracking the direction you flew, how fast, for how long, and what the wind was doing.
Context Anchor
Used in cross-country planning, in-flight position checks, and backup navigation when outside references or electronic navigation are limited.
Derivation
Often thought to come from 'deduced reckoning' (shortened to 'ded. reckoning'), though that origin is disputed. 'Reckoning' simply means 'calculating' — so the term means navigating by calculation alone, without outside fixes to confirm position.
Why Pilots Care
It serves as the fundamental backup navigation method when GPS, VOR, or visual references are lost, allowing continued safe flight and position awareness.
Intuition Check
Dead reckoning does not mean guessing, and it does not mean the aircraft is lost. It means estimating position by calculation from a known starting point.
Example Sentence 1
After the GPS failed, the pilot used dead reckoning to estimate her position based on heading, airspeed, and time since the last checkpoint.
Example Sentence 2
During preflight planning the student laid out a dead reckoning track on the sectional chart using forecasted winds to predict time en route.