Wind Correction

 

FAA and ICAO ,JCAB circling approach protection areas

The circling maneuver area for aircraft is defined by the FAA, ICAO, and Japan’s aviation regulations based on aircraft approach category.

 Below is a comparison of the circling approach protection areas for each:

1. FAA (U.S. – TERPS) Circling Radii

According to FAA TERPS (Terminal Instrument Procedures), the circling maneuvering area is based on approach category and a fixed radius around the runway threshold. The radii are measured from the runway thresholds, assuming a standard height of 1,000 feet AGL.

Aircraft Category	Circling Radius (NM)
A (≤ 90 knots)	1.3 NM
B (91–120 knots)	1.5 NM
C (121–140 knots)	1.7 NM
D (141–165 knots)	2.3 NM
E (166+ knots, military only)	4.5 NM

• The FAA assumes constant wind conditions and does not consider altitude in determining the radius.

2. ICAO (PANS-OPS) Circling Radii

ICAO defines circling areas using a gradient-based method, meaning the required area increases with altitude. The standard radii are:

Aircraft Category	Circling Radius (NM) at 1,000 ft AGL
A (≤ 90 knots)	1.68 NM
B (91–120 knots)	2.66 NM
C (121–140 knots)	4.20 NM
D (141–165 knots)	5.28 NM
E (166+ knots)	6.94 NM

• ICAO PANS-OPS uses a gradient of 20% per 1,000 feet increase in height above the airport. This means circling radii increase with altitude.

• ICAO circling areas are generally larger than FAA’s, accounting for wind and altitude effects.

3. Japan (JCAB - Japanese Civil Aviation Bureau)

Japan follows ICAO PANS-OPS standards for circling approaches. However, Japanese charts may show slight variations based on local conditions or specific procedural requirements.

• In general, JCAB circling areas mirror ICAO radii, including altitude-dependent expansions.

• Japanese approach charts often provide detailed circling restrictions near terrain, similar to ICAO PANS-OPS.

Key Differences Between FAA & ICAO (Japan Follows ICAO)

1. Fixed vs. Variable Radii

• FAA uses fixed-radius circling based on approach category.

• ICAO (and Japan) uses altitude-dependent variable radii, which increase at higher altitudes.

2. Circling Area Size

• ICAO/Japan circling areas are generally larger than FAA’s, especially at high-altitude airports.

3. Wind & Terrain Considerations

• ICAO accounts for wind and altitude effects, while FAA assumes a more simplified model.

 FAA (TERPS) divides circling approach areas into two categories:

1. Standard Circling Area – Used in most cases.

2. Expanded Circling Area – Introduced in 2012 to provide larger maneuvering space, especially for higher-altitude airports.

---

1. FAA Standard Circling Area (Legacy)

• The original circling radii used before the expanded areas were introduced.

• Circling radii were fixed and based solely on the aircraft approach category.

Aircraft Category	Circling Radius (NM)
A (≤ 90 knots)	1.3 NM
B (91–120 knots)	1.5 NM
C (121–140 knots)	1.7 NM
D (141–165 knots)	2.3 NM
E (166+ knots, military only)	4.5 NM

---

2. FAA Expanded Circling Area (Extended)

• Introduced to provide additional safety margins, especially at higher elevations.

• Circling radii increase with airport altitude (similar to ICAO’s method).

• Designed to account for the increased turn radius and descent gradient required at high altitudes.

Aircraft Category	Circling Radius (NM) at Sea Level	Circling Radius (NM) at 5,000 ft MSL	Circling Radius (NM) at 10,000 ft MSL
A (≤ 90 knots)	1.3 NM	1.5 NM	1.8 NM
B (91–120 knots)	1.8 NM	2.0 NM	2.3 NM
C (121–140 knots)	2.8 NM	3.3 NM	3.6 NM
D (141–165 knots)	4.0 NM	4.5 NM	4.8 NM
E (166+ knots)	5.0 NM	5.5 NM	6.0 NM

---

Key Differences Between Standard and Expanded Circling Areas

Factor	Standard Circling	Expanded Circling
Radius Type	Fixed for all airports	Increases with altitude
Introduced	Original TERPS standard	2012 FAA update
Consideration of Altitude	No (same for all altitudes)	Yes (radius increases with elevation)
Wind & Maneuverability	Basic turn radius	Accounts for turn radius at higher altitudes

The expanded circling areas are now commonly used for new instrument approach procedures. However, older approach charts may still use the standard circling areas unless updated.

Would you like a specific example from an approach plate?

Would you like details on specific circling restrictions in Japan or a particular airport example?