FAA Instrument Rating Airplane (IRA)IFR Procedures and ChartsMedium
An en route low-altitude chart depicts a Victor airway between VOR Alpha and VOR Bravo, which are 40 NM apart. Instead of the changeover point (COP) being at the midpoint, the chart shows a COP marked '30/10' along the airway. What is the most likely reason for this nonstandard COP placement?
- AThe COP must always be placed nearer the higher-frequency VOR for interference avoidance
- BTerrain or antenna service volume limitations require the pilot to remain on VOR Alpha's signal longer for reliable reception
- CThe airway's MEA changes at that point, requiring a different altitude
- DATC uses the nonstandard COP solely for traffic sequencing purposes and it has no navigational significance
Show answer & explanationAnswer & explanation
Correct answer: B. Terrain or antenna service volume limitations require the pilot to remain on VOR Alpha's signal longer for reliable reception
A COP is normally at the midpoint between two NAVAIDs, but it may be relocated when needed for better reception based on signal strength, terrain shielding, or other reception issues. The numbers shown (30/10) represent mileage from each facility to the COP, here favoring VOR Alpha due to a reception limitation.
Why the other options are wrong
- A. Frequency has no bearing on COP placement rules.
- C. MEA changes are charted separately, not indicated by COP placement.
- D. COPs are navigational aids for pilots, not ATC sequencing tools.
Changeover Point (COP)
A point along an airway, typically the midpoint between two NAVAIDs, where a pilot changes navigation reference from the station behind to the station ahead.
- Standard COP is midpoint between NAVAIDs
- Nonstandard COPs charted with mileage figures when reception requires it
- Ensures reliable signal reception throughout the airway segment
- Depicted directly on the airway on en route charts
Memory trick: COP keeps you on the clearer signal, not just the closer half.