Circling Approach Calculator

Circling approaches carry their own minimums separate from the straight-in approach, and those minimums depend on which TERPS approach category your aircraft falls into. This calculator derives category from your Vref (or 1.3 times stall speed in landing configuration) using the standard FAA breakpoints — under 91 knots is Category A, up through 121, 141, and 166 knots for B, C, and D, with anything faster landing in Category E — and looks up that category's protected circling radius (1.3 NM for A up to 4.5 NM for E) and minimum required flight visibility (1.0 statute mile for A/B up to 2.0 for D/E) from the legacy standard circling radius table published in FAA Order 8260.3, United States Standard for Terminal Instrument Procedures (TERPS). Note that TERPS has published an expanded, altitude-dependent circling radius table since 2012 that many newer or recently-amended approach charts now use in place of the fixed legacy radii shown here — always check the specific radius printed on your approach plate rather than assuming the fixed table applies.

The circling minimum descent altitude is then the higher of the published straight-in MDA or airport elevation plus the highest obstacle in the circling area plus the required 300 feet of obstacle clearance — TERPS' baseline circling protection margin, unchanged across both the legacy and expanded radius tables. The calculator separately reports whether reported visibility actually meets your category's minimum, plus the headwind and crosswind components for the landing runway using standard trigonometry, the bank angle needed for a standard-rate (3°/second) turn at your approach speed, the resulting turn radius, and a rough time estimate for the circling maneuver (approximated as a semicircle plus final segment). These are planning-grade estimates built from generic TERPS criteria, not a substitute for the actual published approach plate — always fly the minimums, radius, and visibility requirement printed on the chart for your specific airport and approach, since site-specific obstacles can require higher minimums than the generic category table implies.