Definition
A standardized scheme that links each VHF navigation frequency (used by VOR or ILS receivers) to a specific UHF frequency used by the associated DME transponder, so that selecting the VHF frequency on the navigation radio automatically tunes the matched DME channel.
Plain English
A fixed pairing between navigation radio frequencies and DME frequencies. When the pilot tunes the VOR or ILS, the DME automatically tunes itself to the correct partner frequency without any extra action.
Context Anchor
Seen in DME equipment discussions, especially when explaining why tuning one navigation frequency can automatically select the correct DME channel.
Derivation
Pairing means joining two things together as a matched set. Plan here means a published, agreed-upon scheme. So a frequency pairing plan is simply the official chart that says which DME frequency goes with which VOR or ILS frequency.
Why Pilots Care
Reduces cockpit workload by eliminating the need to manually select a separate DME frequency.
Intuition Check
Do not think of this as two radios simply using the same frequency. In DME, the selected navigation frequency is matched to a separate DME channel that uses its own transmit and receive frequencies.
Example Sentence 1
Thanks to the frequency pairing plan, when the pilot tuned the VOR to 113.5, the DME automatically locked onto the matching station and began displaying distance.
Example Sentence 2
Because of the frequency pairing plan, selecting an ILS frequency also activates the associated DME for distance information.