FAA Instrument Rating Airplane (IRA)Navigation SystemsMedium
A pilot is planning an IFR flight and checks the NOTAMs for potential navigation aid outages. The NOTAM indicates that a VOR station along the route is '_UNRELIABLE BEYOND 25NM_'. What does this NOTAM imply for flight planning and execution?
- AThe VOR can be used for en route navigation but not for approaches.
- BThe VOR can only be used for navigation if the aircraft is within 25 NM of the station.
- CThe VOR is completely inoperative and cannot be used for any phase of flight.
- DThe VOR is operating normally, but its signal cannot be received beyond 25 NM due to terrain.
Show answer & explanationAnswer & explanation
Correct answer: B. The VOR can only be used for navigation if the aircraft is within 25 NM of the station.
A NOTAM indicating '_UNRELIABLE BEYOND 25NM_' means that the VOR station is not providing reliable service beyond that specified distance. Therefore, for flight planning and execution, the pilot should only rely on the VOR for navigation when the aircraft is within 25 NM of the station. This implies a reduction in its normal service volume.
Why the other options are wrong
- A. The limitation is based on distance, not specifically on the phase of flight (en route vs. approach), although it would impact both.
- C. The VOR is not completely inoperative; it's unreliable beyond a certain distance.
- D. While terrain could be a cause, the NOTAM simply states 'unreliable' beyond 25 NM, which is a statement of its operational limit, not necessarily the reason for it.
VOR Unreliable NOTAM
A NOTAM indicating a VOR is 'UNRELIABLE BEYOND XNM' means its signal integrity is compromised or cannot be guaranteed past that distance, limiting its usable range for navigation.
- Indicates a reduced service volume.
- Reliable only within the specified distance.
- Requires pilots to plan alternate navigation beyond that range.
Memory trick: Unreliable VOR: Use It Near, Lose It Far.