Subelement K: K – Aircraft— Topic 68: Distance Measuring Equipment
Question 3-68K5
Element 3 (GROL)What radio navigation aid determines the distance from an aircraft to a selected VORTAC station by measuring the length of time the radio signal takes to travel to and from the station?
Explanation
Distance Measuring Equipment (DME) is the correct radio navigation aid. It operates on the principle of a radio transponder system. The aircraft's DME interrogator transmits a pulse-pair signal to a ground-based DME transponder, typically co-located with a VORTAC (VHF Omnidirectional Range/Tactical Air Navigation) station. The ground station receives the signal and replies with its own pulse-pair on a different frequency after a precise delay. The aircraft's DME receiver measures the total time elapsed between sending the interrogation and receiving the reply. Knowing the speed of radio waves and accounting for the fixed transponder delay, the equipment calculates the slant range distance to the ground station.
RADAR is a broader term for Radio Detection And Ranging, not the specific system for measuring distance to a VORTAC. Loran C was a hyperbolic navigation system that measured time differences between signals from multiple synchronized ground stations, not a direct distance measurement to a single VORTAC. "Distance Marking (DM)" is not a recognized aviation radio navigation aid.
Related Questions
3-68K3 The Distance Measuring Equipment (DME) ground station has a built-in delay between reception of an interrogation and transmission of the reply to allow:3-68K4 What is the main underlying operating principle of an aircraft’s Distance Measuring Equipment (DME)?3-68K6 The majority of airborne Distance Measuring Equipment systems automatically tune their transmitter and receiver frequencies to the paired __ / __ channel.3-69K1 All directions associated with a VOR station are related to:3-69K2 The rate that the transmitted VOR variable signal rotates is equivalent to how many revolutions per second?