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This tool applies a standard formula from the relevant domain. The computation is deterministic — given the same inputs, the result is always identical. The formula accounts for the primary variables that determine the output.
FAR 91.155: Class E ≥500 ft below, 1000 ft above, 2000 ft horizontalThe calculation requires: Distance Below Cloud, Distance Above Cloud, Horizontal Distance. Each parameter contributes to the final result according to the formula above. Accuracy depends on the precision of your input measurements.
Updated: July 2026
A typical use case demonstrating the calculator with representative values.
→ Calculated result based on the formula and provided inputs
Enter your own values to get a personalized result for your specific situation.
→ Result calculated from your specific input values
Check the expected unit for each input field (shown as suffix). Converting between imperial and metric units before entering values prevents calculation errors.
When a formula combines multiple measurements, all inputs must use compatible units. Convert everything to the same system (metric or imperial) before calculating.
Check minimum VFR cloud clearance distances for Class E airspace below 10,000 ft. Free vfr cloud clearance tool for vfr, cloud, and more. It applies the calculation formula (FAR 91.155: Class E ≥500 ft below, 1000 ft above, 2000 ft horizontal). For example: 400 below, 800 above, 1500 horizontal — A typical use case demonstrating the calculator with representative values.