Definition
The standard minimum rate of altitude gain required on a published instrument departure procedure, expressed as 200 feet of climb for every nautical mile of horizontal distance flown over the ground. This gradient is the default obstacle clearance design assumption for instrument departures unless a higher gradient is published for a specific procedure.
Plain English
On a standard instrument departure, your aircraft must climb at least 200 feet for every nautical mile you travel forward. If you can't meet this rate of climb, you can't safely fly the procedure as designed.
Context Anchor
Seen in instrument departure procedure design, obstacle clearance discussions, and IFR departure planning.
Derivation
A 'gradient' comes from the Latin gradus, meaning 'step.' A climb gradient measures how steeply the aircraft 'steps up' through the air relative to the ground it covers — vertical feet gained per horizontal nautical mile traveled.
Why Pilots Care
Meeting this gradient ensures the aircraft clears all obstacles in the departure path even in instrument conditions.
Analogy
Think of it like the steepness of a road. The question is not just how fast you are going, but how much higher you get over a certain distance.
Grounding Statement
One nautical mile after the starting point, the aircraft should be at least 200 feet higher; two nautical miles later, at least 400 feet higher.
Intuition Check
Do not read this as a climb rate in feet per minute. It is a climb requirement based on distance traveled over the ground.
Example Sentence 1
The departure procedure required the standard minimum climb gradient of 200 ft/NM, so at our planned groundspeed of 120 knots we needed at least 400 feet per minute on the climb.
Example Sentence 2
If the aircraft cannot achieve the minimum climb gradient of 200 ft/NM, an alternate departure must be used.