RAD NAV: MANUAL PRIORITY, AUTOMATIC TUNING AND ILS VALIDATION
The RADIO NAV page allows inspection and, where appropriate, manual tuning of navigation aids. In the cited standard, a manually tuned selection has priority over automatic tuning until cleared. That is useful for deliberate monitoring and hazardous when forgotten after a route or runway change. Inspect how the receiver was selected as well as the identifier currently printed beside it. [66, PDF pp. 469-480,495]
1. Establish the intended aid. Compare the charted aid and its role with the actual route or monitoring task. Enter either the supported identifier or frequency form. The source explicitly rejects simultaneous identifier/frequency entry as FORMAT ERROR for its tuning operation. Do not infer entry grammar from the combined ident/frequency value subsequently displayed after a valid single input. [66, PDF pp. 469-480,495]
2. Resolve identity after frequency entry. A frequency can be used by more than one installation. The source describes a nearest associated identifier being displayed, so frequency acceptance alone is not a complete identification check. Compare the actual received identification, geographical context and chart. Raw signal reception and database-based selection answer related but separate questions. [66, PDF pp. 469-480,495]
3. Review the ILS and course. For the actual selected departure or arrival, compare identifier, frequency and front-course reference with the current chart. A course is not a heading instruction. Back-beam options in the guide are configuration-dependent; do not create a generic back-course procedure from their presence. A manual override remaining from the earlier runway may require explicit clearance even after the approach selection changes. [66, PDF pp. 469-480,495]
4. Return to automatic tuning deliberately. Use CLR on the manually entered selection when it is no longer required, then inspect the result. The documented receiver returns to automatic tuning or brackets if nothing suitable is auto-tuned. Only manually entered courses have the described clearing behaviour. Verify the subsequent actual selection rather than assuming a cleared field means the receiver stopped receiving or selected the new runway correctly. [66, PDF pp. 469-480,495]
5. Cross-check before use. Read the selected/received aid with raw deviations, aircraft position and current approach, especially after vectors or a late runway change. A correct flight-plan line does not prove correct radio tuning, and a centred radio indication is not proof that the intended procedure was selected. Keep those independent checks in the approach review and read the actual FMA when arming/capturing guidance. [66, PDF pp. 469-480,495]