8.circling-approach. Circling Approach
A circling approach is the visual phase of an instrument approach used to align the aircraft with a runway when a straight-in landing from an instrument approach is not possible or desirable. Circling is published when the final approach course is more than 30° offset from the runway centerline (15° for GPS approaches in some cases), when the descent gradient for a straight-in is excessive, or when the landing runway is different from the one served by the final approach course.
When Circling Is Required
- The approach procedure is titled with only a circling line of minima (e.g., "VOR-A" or "RNAV (GPS)-B"). The letter suffix instead of a runway number indicates circling-only minimums.
- Wind, runway length, or operational considerations dictate landing on a runway other than the one aligned with the final approach course.
- ATC assigns a circling approach.
Circling Minimums and Protected Airspace
Circling MDA and visibility are listed separately on the approach chart. The circling area is protected airspace within which obstacle clearance of at least 300 feet is guaranteed, provided the aircraft remains within the prescribed radius from the runway thresholds.
Two standards exist for defining circling protected airspace:
- Standard (pre-2012) circling areas use fixed radii based solely on aircraft approach category:
- Category A: 1.3 NM
- Category B: 1.5 NM
- Category C: 1.7 NM
- Category D: 2.3 NM
- Category E: 4.5 NM
- Expanded (TERPS) circling areas account for true airspeed at higher airport elevations and use larger radii. Charts using the expanded area are marked with a negative C in a black box symbol next to the circling minimums.
Aircraft approach category is determined by 1.3 × VSO at maximum certificated landing weight (VREF):
- Category A: less than 91 knots
- Category B: 91 to 120 knots
- Category C: 121 to 140 knots
- Category D: 141 to 165 knots
- Category E: 166 knots or more
If a higher speed is flown during the circling maneuver, the pilot must use the minimums for the higher category.
Executing the Circling Maneuver
Upon completing the instrument portion of the approach and acquiring the required visual references, the pilot maneuvers the aircraft visually at or above the circling MDA until in a position to descend for a normal landing. Key procedural points:
- Do not descend below circling MDA until in a position from which a normal descent to landing using normal maneuvers can be made, and the runway environment is in sight.
- Maintain the circling MDA precisely; even small altitude losses can compromise the 300 ft obstacle clearance.
- Keep the airport or runway environment in sight at all times. If visual reference is lost while circling, immediately execute the missed approach.
- Stay within the protected circling radius for your category.
- Use shallow bank angles (typically 20-30°) appropriate for the airspeed and visibility.
Common Circling Patterns
The specific ground track depends on the relationship between the final approach course and the landing runway. Typical maneuvers include:
- Crossing midfield and entering a downwind on the appropriate side.
- Flying parallel to the landing runway on a teardrop, then turning base and final.
- A direct turn to base when the geometry permits.
The pilot should brief the intended pattern before beginning the approach, including the direction of turns, descent point from MDA, and missed approach procedure.
Missed Approach From Circling
If visual contact with the runway environment is lost while circling, the AIM and TERPS prescribe a specific procedure: make an initial climbing turn toward the landing runway and continue the turn until established on the published missed approach course. This ensures the aircraft remains within the circling protected area while transitioning to the missed approach segment. Once established on the missed approach course, fly the published procedure.
Restrictions and Cautions
- Some approach charts prohibit circling in certain sectors (e.g., "Circling NA east of Runway 18-36") due to obstacles or terrain. These restrictions are mandatory.
- Circling at night, especially in marginal weather, is one of the highest-risk maneuvers in instrument flying. Many operators and Part 121/135 operations prohibit night circling or require higher minimums.
- Wind, low ceilings, and reduced visibility shrink the margin between the protected area and obstacles. Pilots should add personal minimums when conditions are marginal.
- Single-pilot IFR circling at minimums in IMC requires precise altitude control, situational awareness, and immediate willingness to execute the missed approach.
Example
Flying a VOR-A approach into a non-towered field with circling-only minimums of 1240-1 (Cat B), the pilot levels at 1240 ft MSL, identifies the runway visually, and maneuvers to enter a left downwind for Runway 27. Maintaining 1240 ft until abeam the threshold, the pilot turns base, descends, and lands. Throughout the maneuver the aircraft remains within 1.5 NM of the runway threshold, satisfying Cat B circling protection.