Definition
A climb gradient expressed as a required altitude gain of 500 feet for every nautical mile flown over the ground. It is the standard minimum climb gradient assumed for instrument departure procedures unless a higher value is published.
Plain English
For every nautical mile you travel forward, you must climb at least 500 feet. Fly one mile, gain 500 feet of altitude — that is the standard climb performance instrument departures are designed around.
Context Anchor
Seen in instrument departure and approach procedure discussions where a required climb or descent path is described.
Why Pilots Care
It defines the minimum aircraft performance needed to clear terrain and obstacles when following an instrument procedure.
Analogy
Think of it like a hill: for each nautical mile forward, the airplane has to be 500 feet higher.
Grounding Statement
At 500 ft/NM, after 2 nautical miles the aircraft should be about 1,000 feet higher than where it started.
Intuition Check
Do not read 500 ft/NM as 500 feet per minute. It is based on distance traveled, not time elapsed.
Example Sentence 1
Before departure, the pilot calculated that the aircraft could meet the 500 ft/NM standard climb gradient at the current weight and temperature.
Example Sentence 2
If your aircraft cannot sustain 500 ft/NM, select an alternate departure route or delay until conditions improve.