8.approach-categories. Aircraft Approach Categories
Aircraft approach categories are groupings of aircraft based on a reference landing speed (V_REF), or if V_REF is not specified, 1.3 times the stall speed in the landing configuration at the maximum certificated landing weight (1.3 V_SO). The categories determine which line of approach minimums a pilot uses on an Instrument Approach Procedure (IAP) chart and the protected obstacle clearance areas around the procedure. They are defined in 14 CFR Part 97 and used throughout the U.S. Terminal Procedures Publication (TPP).
The five approach categories are:
- Category A: Speed less than 91 knots.
- Category B: Speed 91 knots or more but less than 121 knots.
- Category C: Speed 121 knots or more but less than 141 knots.
- Category D: Speed 141 knots or more but less than 166 knots.
- Category E: Speed 166 knots or more.
Approach minimums on an IAP chart are published by category. The MDA/DA, visibility, and missed approach obstacle clearance areas all expand as category increases because faster aircraft need more room to maneuver, particularly during a circling approach.
Determining the correct category. An aircraft is certificated in a single category based on its V_REF or 1.3 V_SO at maximum landing weight. For most light general aviation airplanes (Cessna 172, Piper Cherokee, Cirrus SR22) this places them in Category A. A King Air or light jet typically falls into Category B or C. The category in the Aircraft Flight Manual (AFM) is the baseline.
However, the regulations recognize that real-world approach speeds may be higher than V_REF. If a pilot chooses to fly an approach faster than the upper limit of the aircraft's certificated category, the higher category minimums must be used. This commonly happens during circling approaches in gusty wind conditions, when ice has accumulated, or when a higher-than-normal final approach speed is flown for stability or company procedure.
Example: A Category B airplane with a V_REF of 100 knots is flown at 125 knots on the approach due to a gust additive and operational considerations. The pilot must use Category C minimums for that approach, including any higher MDA/DA, visibility, and the larger circling protected area.
Why this matters — circling approach areas. The obstacle clearance area for the circling maneuver is the most safety-critical application of categories. Under the older TERPS criteria, circling radii were:
- Cat A: 1.3 NM
- Cat B: 1.5 NM
- Cat C: 1.7 NM
- Cat D: 2.3 NM
- Cat E: 4.5 NM
Under the newer expanded circling approach radii (indicated by an inverse-C symbol, a black "C" inside a white box, on the chart), the radii are larger and vary with airport elevation to account for true airspeed. For example, at sea level the expanded Cat C radius is 2.7 NM, increasing further at higher field elevations. If the inverse-C symbol is present on the IAP, the pilot must remain within the new, larger radius from the runway threshold(s) for the appropriate category.
Reading the minimums section. On a U.S. IAP chart, the MINIMUMS box is divided into columns labeled CATEGORY A, B, C, D (and E if applicable). Within each column the chart lists the straight-in minimums (S-ILS, S-LOC, S-LNAV, etc.), the CIRCLING minimums, and the required visibility, often with HAT (Height Above Touchdown) or HAA (Height Above Airport) noted. If two categories share the same minimums, they may be combined (e.g., "A/B").
Practical procedures for the pilot:
- Before the approach, identify the certificated category from the AFM or POH.
- Determine the actual approach speed to be flown, including any gust factor or icing additive.
- If the actual speed exceeds the upper limit of the certificated category, use the next higher category's minimums.
- Brief the correct line of minimums (DA/MDA and visibility), the missed approach point, and circling protected radius.
- For circling, check whether the inverse-C symbol is published; if so, use the expanded radii table from the front of the TPP.
Common errors:
- Using Category A minimums for a circling approach flown at 110 knots (which is Category B speed).
- Forgetting to switch categories when adding a 10–20 knot gust factor.
- Confusing aircraft category with aircraft class (single-engine land vs. multi-engine land); category here refers strictly to approach speed.
Understanding categories is fundamental: they are the bridge between the airplane's actual landing performance and the protected airspace TERPS designers built into the procedure. Using the wrong category can place an aircraft outside the obstacle clearance area without the pilot ever realizing it.