How can a pilot determine if DME is available on an ILS/LOC?

The method of verifying the DME/TACAN channel in the LOC frequency box is the most effective way for a pilot to determine if Distance Measuring Equipment (DME) is available on an Instrument Landing System (ILS) or Localizer (LOC) approach.

When a pilot sets up for an ILS approach, the frequencies used for the LOC often have associated DME capabilities. This information is typically indicated in the navigation data available on the aircraft's avionics systems. By checking the frequency box for the LOC, the pilot can confirm whether a corresponding DME/TACAN channel is included. If it is, that means DME service is on the frequency, which helps in providing distance information to the pilot during the approach.

This option is rooted in the specific navigational aids and their integration into approach procedures, highlighting the importance of reviewing both ILS and DME capabilities before initiating an approach.