Definition
A climb gradient expressed as 1,000 feet of altitude gained for every nautical mile of distance flown over the ground. It is the standard climb performance reference used in instrument departure procedures when a higher-than-standard climb gradient is required for obstacle clearance.
Plain English
For every nautical mile you travel forward, the aircraft must climb 1,000 feet higher. It is a way of measuring how steeply the aircraft must climb during a departure.
Context Anchor
Seen on instrument procedure charts and in discussions of required climb or descent paths, especially where terrain or obstacles must be cleared.
Why Pilots Care
Meeting the gradient keeps the aircraft clear of terrain and obstacles during instrument departures and ensures proper path alignment on approaches.
Analogy
It is like describing a steep hill by how much it rises for each mile forward, except aviation uses nautical miles instead of regular road miles.
Grounding Statement
Picture the airplane moving one nautical mile across the ground and ending up 1,000 feet higher or lower than where it started.
Intuition Check
Do not read 1,000 ft/NM as feet per minute. It is altitude change per nautical mile of ground distance, not altitude change per minute of time.
Example Sentence 1
The departure procedure required a minimum climb gradient of 1,000 ft/NM until reaching 3,500 feet, so the pilot calculated a required climb rate of 1,500 feet per minute at the planned groundspeed.
Example Sentence 2
The approach chart shows a descent gradient of 1,000 ft/NM to maintain the published vertical path.