Which formula is used to calculate circling minima from MDA?

Which formula is used to calculate circling minima from MDA?

• A. MDA/100 x 3
• B. MDA + 100 x 3
• C. MDA x 3
• D. MDA - 100 x 3

Answer: (A)

Circling minima must include extra clearance for maneuvering from the approach to a landing, so the published MDA is raised by a fixed amount to form the circling minimum altitude. The standard method is to add 300 feet to the MDA (that’s MDA plus 100 feet times 3). This 300 ft margin accounts for potential altitude deviations during the circling turn, bank angle, and the need to establish the runway visually with enough obstacle clearance. So the circling minimum altitude is MDA + 300 ft, then rounded as required by chart conventions. The other ways of combining the numbers—dividing MDA, tripling it, or subtracting 300 ft—do not provide the necessary additional clearance for the circling maneuver.

Circling minima must include extra clearance for maneuvering from the approach to a landing, so the published MDA is raised by a fixed amount to form the circling minimum altitude. The standard method is to add 300 feet to the MDA (that’s MDA plus 100 feet times 3). This 300 ft margin accounts for potential altitude deviations during the circling turn, bank angle, and the need to establish the runway visually with enough obstacle clearance.

So the circling minimum altitude is MDA + 300 ft, then rounded as required by chart conventions. The other ways of combining the numbers—dividing MDA, tripling it, or subtracting 300 ft—do not provide the necessary additional clearance for the circling maneuver.