FAA Airline Transport Pilot (ATM)Navigation, Air Traffic Control and ProceduresHard
A VOR federal airway (Victor airway) is protected for 4 nautical miles on each side of the centerline near the defining VOR stations. Based on the standard 4.5-degree divergence angle used to define the airway boundaries, at what distance from the VOR does the protected width begin to expand beyond 4 NM on each side?
- A25 nautical miles
- B100 nautical miles
- C51 nautical miles
- D70 nautical miles
Show answer & explanationAnswer & explanation
Correct answer: C. 51 nautical miles
Federal (Victor) airways are protected for 4 NM on each side of the centerline out to 51 NM from the VOR, based on the 4.5-degree splay angle from the station (tan 4.5° × 51 NM ≈ 4 NM). Beyond 51 NM, the protected width widens because the angular divergence continues to increase with distance.
Why the other options are wrong
- A. 25 NM is well within the 4 NM constant-width zone.
- B. 100 NM is far beyond the transition point and well into the expanded-width zone.
- D. 70 NM already lies within the widened portion of the airway.
Federal Airway (Victor Airway) Width
VOR-based federal airways are protected for 4 NM on each side of the centerline near the VOR, widening based on a 4.5-degree angle beyond 51 NM from the station.
- Standard protected width: 4 NM each side of centerline (8 NM total)
- Width is constant out to 51 NM from the defining VOR
- Beyond 51 NM, width increases per a 4.5° divergence angle
- Airways are typically 8 NM wide near navaids used to define them
Memory trick: '51 is the split point' — width holds at 4 NM until 51 NM, then spreads