Radio Navigation and Instrument Procedures
Radio Navigation and Instrument Procedures tests VOR, NDB, ILS, GNSS and RNAV use, holding entries, approach clearance and instrument procedure interpretation.
Radio aids
- VOR: selected radial is from the station; CDI centred with TO means tracking to the station. Reverse sensing occurs when tracking away with a TO indication.
- NDB: ADF points to the station; relative bearing plus heading gives magnetic bearing.
- ILS: localizer gives lateral guidance, glideslope gives vertical guidance. A 3° glideslope is about 318 ft per nautical mile.
- GNSS/RNAV: check RAIM, database validity and desired course; RNAV does not remove terrain responsibility.
Procedures
- Holding: standard right turns, inbound leg timing or distance as published. Enter according to the bearing to the fix.
- Approach clearance: fly the published procedure, brief the missed approach, and do not descend below minima without the required visual reference.
Worked example
On a 3° ILS glideslope at 4 NM from the threshold, the nominal height is 4 × 318 ≈ 1,272 ft above threshold. At 2 NM it is about 636 ft. If the aircraft is below the glideslope, do not chase it aggressively; fly the correct vertical path and go around if unstable.
Traps
Reverse sensing on a VOR or NDB; using a false glideslope at high angles; forgetting the missed approach before starting the approach; descending below minima without visual reference; ignoring NOTAM changes to a procedure.