Definition
A required rate of altitude gain expressed as feet of climb per nautical mile of horizontal distance flown, used to ensure obstacle clearance during departure, missed approach, or when crossing a fix at or above a specified altitude. Climb gradients are published in feet per nautical mile (ft/NM) and must be converted to a feet-per-minute (ft/min) rate of climb based on the aircraft's groundspeed.
Plain English
A climb gradient tells a pilot how much altitude they must gain for every mile they travel forward. It is a slope, not a speed. The faster the airplane is moving over the ground, the higher the rate of climb in feet per minute needed to meet that same slope.
Context Anchor
Seen in instrument procedure discussions, departure instructions, and minimum crossing altitude planning, where the aircraft must reach a certain altitude by a certain point.
Derivation
Gradient comes from the Latin gradus, meaning 'a step' or 'degree of slope.' In aviation it keeps that sense of slope — how steeply the aircraft must climb across the ground.
Why Pilots Care
Meeting the published climb gradient guarantees obstacle clearance; falling short can result in terrain conflict even if the aircraft is climbing.
Analogy
Think of a climb gradient like the steepness of a hill on a road. The slope of the hill stays the same whether you drive fast or slow — but the faster you drive up it, the faster your altitude increases per minute.
Intuition Check
Do not treat climb gradient as the same thing as climb rate. Climb rate is how much altitude is gained per minute; climb gradient is how much altitude is gained over distance traveled.
Example Sentence 1
The departure procedure required a climb gradient of 250 feet per nautical mile until reaching 4,000 feet.
Example Sentence 2
During the missed approach, the pilot verified the aircraft could maintain the published climb gradient before turning.