Definition
A navigation procedure used to estimate the time and distance to a VOR or NDB station by flying a known heading perpendicular to the bearing to the station and timing how long it takes the bearing to change by a specified number of degrees. The result gives the pilot a usable estimate of minutes to the station and nautical miles to the station, based on groundspeed.
Plain English
A simple in-flight calculation that tells the pilot roughly how many minutes and how many miles they are from a navigation station, by turning to fly across the line to the station and timing how fast the bearing changes.
Context Anchor
Seen in radio-navigation work with an RMI when the pilot needs distance information from a ground station without a direct distance readout.
Why Pilots Care
Gives a reliable backup method to determine position and arrival time when distance measuring equipment is unavailable or to cross-check other instruments.
Grounding Statement
If the station pointer changes direction quickly, the airplane is relatively close to the station; if it changes slowly, the airplane is farther away.
Intuition Check
A time and distance check is not just checking the clock and checking mileage. In this FAA context, it means timing a change in the station pointer and using that timing to estimate distance from the station.
Example Sentence 1
With no DME on board, the pilot used a time and distance check from the VOR to estimate they were about 18 minutes from the station.
Example Sentence 2
After completing the time and distance check, the pilot adjusted the estimated arrival time based on the calculated distance.