Definition
A VOR navigation procedure used to estimate the time and distance from the aircraft to a VOR station by measuring how long it takes a selected radial to drift across the Course Deviation Indicator (CDI) while flying a heading 90 degrees off that radial. The elapsed time between bearing changes, combined with the aircraft's groundspeed, is used in standard formulas to calculate minutes and nautical miles to the station.
Plain English
A simple in-flight method to figure out how far you are from a VOR station, and how long it will take to get there, by flying at a right angle to the station and timing how quickly your position relative to the station changes on the cockpit indicator.
Context Anchor
Used during VOR navigation when the airplane does not have equipment that directly displays distance from the station, or when the pilot wants to cross-check position using basic navigation instruments.
Why Pilots Care
Gives pilots without distance-measuring equipment a practical way to estimate arrival time and fuel requirements during instrument or cross-country flight.
Grounding Statement
A nearby station appears to move across the CDI faster than a faraway station, just as a nearby roadside sign seems to pass faster than a distant mountain.
Intuition Check
Station does not mean an airline gate or a person talking on the radio here; it means the ground radio navigation facility the CDI is referencing. The CDI does not directly show distance; the pilot estimates distance by timing how fast the CDI indication changes.
Example Sentence 1
With no DME on board, the pilot performed a time and distance check from a station using a CDI to estimate they were about 18 nautical miles from the VOR.
Example Sentence 2
After finishing the time and distance check from the station using a CDI, the crew adjusted their estimated time of arrival and fuel planning.