Instrument Rating – Helicopter › V. Navigation Systems › Task A. Intercepting and Tracking Navigational Systems and DME Arcs

IH.V.A.S6

Skill

Apply proper correction to maintain a course, allowing no more than ¾-scale deflection of the course deviation indicator (CDI). If a distance measuring equipment (DME) arc is selected, maintain that arc ±1 nautical mile.

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Study note

Get a short, cited explanation of this element written from the FAA handbooks: the core idea, the numbers that matter, common test traps, and a quick self-check.

From the FAA library

Instrument Flying Handbook p. 9-17
Chapter 9: Navigation Systems › Traditional Navigation Systems › DME Arc
This is useful when you make an ILS approach at a facility that has no collocated DME, but there is a VOR/DME nearby. Altitude Some DMEs correct for slant-range error. Function of DME A DME is used for determining ... distance from a ground DME transmitter. Compared to other VHF/UHF NAVAIDs, a DME is very accurate. The distance information can be used to determine the aircraft position or flying a track that is a constant distance from the station. This…
Pilot's Handbook of Aeronautical Knowledge p. 16-27
Chapter 16: Navigation › Angle of Intercept › Distance Measuring Equipment (DME)
Distance Measuring Equipment (DME) Distance measuring equipment (DME) consists of an ultra high frequency (UHF) navigational aid with VOR/DMEs and VORTACs. It measures, in NM, the slant range distance of an aircraft from a VOR/DME or VORTAC (both hereafter referred ... VORTAC). Although DME equipment is very popular, not all aircraft are DME equipped. To utilize DME, the pilot should select, tune, and identify a VORTAC, as previously described. The DME receiver, utilizing what is called a “paired frequency” concept, automatically…
Aeronautical Information Manual p. 1-1-5
Chapter 1. Air Navigation › Section 1. Navigation Aids › 1-1-7. Distance Measuring Equipment (DME)
Distance Measuring Equipment (DME) a. In the operation of DME, paired pulses at a specific spacing are sent out from the aircraft (this is the interrogation) and are received at the ground station. The ground station (transponder) then transmits paired ... pulse spacing but on a different frequency. The time required for the round trip of this signal exchange is measured in the airborne DME unit and is translated into distance (nautical miles) from the aircraft to the ground station…
Instrument Procedures Handbook p. 4-42
Chapter 4: Approaches › DME Arcs
These routes are initial approach segments because they begin at the IAF. Like feeder routes, they are depicted with course, minimum altitude, and distance to the IF. Essentially, these routes accomplish the same thing as feeder routes but they originate ... whereas feeder routes terminate at an IAF. [Figure 4-30 ] DME Arcs DME arcs also provide transitions to the approach course, but DME arcs are actually approach segments while feeder routes, by definition, are not. When established on a DME…
Instrument Flying Handbook p. 9-17
Chapter 9: Navigation Systems › Traditional Navigation Systems › DME Components
DME Components VOR/DME, VORTAC, ILS/DME, and LOC/DME navigation facilities established by the FAA provide course and distance information from collocated components under a frequency pairing plan. DME operates on frequencies in the UHF spectrum between ... Aircraft receiving equipment that provides for automatic DME selection assures reception of azimuth and distance information from a common source when designated VOR/ DME, VORTAC, ILS/DME, and LOC/DME are selected. Some aircraft have separate VOR and DME receivers, each…