Definition
A unit expressing a required climb or descent gradient as the number of feet of altitude change for each nautical mile flown over the ground. Used on instrument departure and approach procedures to specify minimum climb gradients or descent paths independent of aircraft groundspeed.
Plain English
How many feet you must climb (or descend) for every nautical mile you travel forward. It describes the steepness of the path, not how fast you're flying.
Context Anchor
Seen in instrument departure procedures, especially where a published climb gradient is required after takeoff.
Why Pilots Care
Confirms the aircraft can meet the performance needed for safe obstacle clearance during departures in instrument conditions.
Analogy
Think of it like the steepness of a road. FPNM describes how much the path rises for each fixed distance forward.
Grounding Statement
A higher FPNM number means the airplane must climb more steeply over the same forward distance.
Intuition Check
Do not confuse FPNM with feet per minute. FPNM is based on distance traveled, not on elapsed time.
Example Sentence 1
The departure procedure required a minimum climb gradient of 250 FPNM until reaching 3,000 feet.
Example Sentence 2
At 90 knots groundspeed the pilot converted the 200 FPNM requirement into a required rate of climb.