FAA Instrument Flight Instructor (FII)IFR Procedures and ApproachesHard
A pilot is planning an ILS approach to an airport where the published localizer frequency is 110.30 MHz. The pilot notices that the approach plate also indicates a DME channel. How does the DME channel relate to the localizer frequency for this approach?
- AThe DME channel is only used for RNAV approaches, not ILS.
- BThe DME channel provides a backup in case the localizer fails.
- CThe DME channel is automatically tuned when the localizer frequency is selected.
- DThe DME channel is a separate frequency that must be tuned manually.
Show answer & explanationAnswer & explanation
Correct answer: C. The DME channel is automatically tuned when the localizer frequency is selected.
ILS localizer frequencies are paired with specific DME (Distance Measuring Equipment) channels. When a pilot tunes the localizer frequency (e.g., 110.30 MHz) on their navigation radio, the associated DME channel is automatically tuned by the aircraft's avionics. This allows the DME to provide distance information relative to the localizer antenna without requiring a separate manual tuning action.
Why the other options are wrong
- A. DME can be used with both VOR and ILS approaches, as well as with RNAV procedures for cross-checking.
- B. DME provides distance information, not a backup for the localizer's course guidance.
- D. DME channels are paired with VOR/ILS frequencies and are typically automatically tuned, not manually.
ILS Frequency Pairing (DME)
ILS localizer frequencies are paired with specific DME (Distance Measuring Equipment) channels, enabling automatic tuning of the DME when the localizer frequency is selected.
- Localizer frequencies are VHF, DME channels are UHF.
- The pairing allows DME to provide distance to the localizer (or VOR) facility.
- Automatic tuning simplifies pilot workload.
Memory trick: Tune the Localizer, DME Joins the Party.