Climb Gradient Calculations – SID Charts

The climb gradient is the rate of climb expressed as a percentage of altitude gain per unit of horizontal distance traveled (typically expressed in feet per nautical mile). It represents the minimum rate of climb required to safely clear obstacles and terrain during departure.

To calculate climb gradient, you divide the altitude gain required (in feet) by the horizontal distance traveled (in feet) and then multiply the result by 100 to convert it to a percentage.

For example, if you need to climb 300 feet in 1 nautical mile, the climb gradient would be (300 / 1*6076) * 100 = 4.9% approx.

1 NM = 6076 feet

 

Vertical speed (or climb rate) is the rate at which an aircraft gains altitude, typically expressed in feet per minute (ft/min). It is calculated based on the desired climb gradient and groundspeed.

Vertical Speed (ft/min) = Climb Gradient (%) * Groundspeed (knots)/60 

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