Climb Gradient Calculator

Climb Gradient converts a rate-of-climb figure into the ft/NM units departure procedures actually publish, using Gradient = (Rate of Climb / Ground Speed) x 60 -- a formula that involves only those two inputs, so Required Gradient never changes the Climb Gradient reading itself; it only sets the bar the calculated gradient is compared against. Because Ground Speed sits in the denominator, a faster climb speed at the same rate of climb actually produces a shallower gradient in ft/NM -- this is a common point of confusion for pilots used to thinking "faster is better," when in fact a slower Vy-speed climb at the same vertical rate covers less horizontal distance per foot gained and clears obstacles more steeply. ROC Needed for Requirement runs the same relationship in reverse: it answers what rate of climb, at your planned Ground Speed, would be needed to meet Required Gradient, and it depends only on those two inputs -- your actual Rate of Climb plays no role in that particular figure, since it describes a target rather than your current performance.

Obstacle Height and Obstacle Distance activate a separate clearance check only when both are entered above zero; left at their default of zero, the calculator treats the departure as having no specific charted obstacle to clear beyond the general climb-gradient requirement. The obstacle check applies a standard 35-foot clearance margin, matching the 35-foot screen height used in FAR Part 25/121 takeoff performance and obstacle-clearance calculations (a distinct concept from the FAA's sloped Part 77/TERPS obstacle identification surfaces), and assumes the aircraft flies the gradient exactly, with no wind-drift or turn-radius deviation from the runway centerline extended track.