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Which information must be known to use dead reckoning accurately?
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navigation
Officers on a passenger ship using charts for navigation.
To use dead reckoning accurately, a navigator must determine their position based on several key pieces of information. The process requires knowing the following data points:
- Known starting point: A reliable initial position from which all subsequent calculations begin.12
- Course: The direction in which the ship or aircraft is steered or headed.12
- Distance or velocity: The distance traveled, which is estimated based on the craft's speed through the water or air.12
- Drift: The estimated or known effect of external forces—such as wind, ocean currents, or tidal streams—that push the craft off its intended path.12
Because errors in these measurements accumulate over time, dead reckoning is often supplemented by celestial navigation or other fixes to reinitialize the starting point. In modern applications, these calculations are frequently handled by dead-reckoning computers or inertial guidance systems, which may mathematically combine multiple navigation solutions to provide the most accurate estimate of position and velocity.12