Climb Gradient to Rate of Climb

Reconciles a departure's climb GRADIENT (feet per nautical mile, the obstacle-clearance slope) with the cockpit rate of climb (feet per minute) through the ground speed: ROC = gradient x ground speed / 60. A 300 ft/nm gradient at 120 kt needs 600 ft/min; the gradient as a percent is ft/nm over 6076.12 (the 200 ft/nm default is ~3.3%). The trap: because it scales with GROUND speed, flying faster or a tailwind demands a HIGHER rate of climb for the same gradient, and a heavy, high-density-altitude departure may not make a steep gradient at all -- the takeoff go/no-go. A planning aid; the departure procedure and performance charts govern.

roc_fpm = climb_gradient_ft_per_nm x ground_speed_kt / 60; gradient_percent = climb_gradient_ft_per_nm / 6076.12 x 100; gradient_deg = atan(climb_gradient_ft_per_nm / 6076.12).

Climb gradient to rate of climb (FAA TERPS / AIM departure procedures), by name; the departure procedure and aircraft performance charts govern.

The gradient-to-rate conversion is first-principles; the required gradient comes from the departure procedure and the ground speed from the flight instruments.

Estimate. AHJ and licensed professional govern.

Field names used by the API: climb_gradient_ft_per_nm, ground_speed_kt, roc_fpm, gradient_percent

• Ground speed drives it the required rate of climb scales with ground speed for a fixed gradientFAA TERPS
• Standard default the standard obstacle departure gradient is 200 ft/nm (~3.3%) unless a steeper one is publishedFAA AIM