Definition
The highest rate of descent, in feet per minute, that a pilot may use on the final approach segment of an instrument approach without going below the published vertical path or descent profile. These rates are tied to the aircraft's groundspeed and the descent angle of the approach, and they are tabulated on instrument approach charts so the pilot can confirm a safe rate of descent for the speed being flown.
Plain English
The fastest you are allowed to descend on final approach so you stay on the correct glide path. The faster you are flying over the ground, the steeper the descent in feet per minute needs to be to stay on profile -- but the chart gives you a ceiling you should not exceed.
Context Anchor
Seen in instrument approach planning and descent discussions, especially when checking whether an approach can be flown at a safe, manageable rate of descent.
Why Pilots Care
Exceeding these rates can cause loss of required obstacle clearance, leading to unsafe flight paths or CFIT risk.
Grounding Statement
A descent rate that looks fine on paper may become unacceptable if the airplane must lose too much altitude in too little time.
Intuition Check
Do not read “acceptable” as “comfortable” or “preferred.” Here it means a descent rate that is still considered suitable for safely flying the published procedure.
Example Sentence 1
During the approach briefing, the captain noted the maximum acceptable descent rate of 750 feet per minute for their groundspeed of 90 knots on the 3-degree glide path.
Example Sentence 2
Reviewing the maximum acceptable descent rates before starting the approach helped the crew plan a stable descent profile.