Definition
For a multi-engine airplane with one engine inoperative, the single-engine service ceiling is the maximum density altitude at which the airplane can still maintain a steady climb of 50 feet per minute at the best single-engine rate-of-climb speed (VYSE), with the critical engine failed and feathered, the operating engine at maximum continuous power, and the airplane in a clean configuration at maximum certificated takeoff weight.
Plain English
The highest altitude a twin-engine airplane can still slowly climb after losing one engine. Above this altitude, the airplane can no longer climb on the remaining engine and will begin to drift down.
Context Anchor
Seen in multiengine performance charts and discussions of how much climb capability remains after an engine failure.
Derivation
Ceiling comes from the idea of an upper limit, like the top of a room. In aviation performance, it means the upper altitude limit where the airplane can still meet a stated climb rate. Single-engine points to the condition being measured: one engine is no longer helping.
Why Pilots Care
Sets the highest altitude a pilot can safely continue flight after losing an engine without descending.
Grounding Statement
At the single-engine service ceiling, the airplane can still climb, but only very slowly: 50 feet per minute.
Intuition Check
Do not read ceiling here as a cloud ceiling or a cockpit roof. It means a performance limit: the highest adjusted altitude where the airplane can still meet the required one-engine climb rate.
Example Sentence 1
Before departing for a flight across the mountains, the pilot checked the single-engine service ceiling and confirmed it was high enough to clear the ridges if one engine failed.
Example Sentence 2
With one engine shut down, the airplane could no longer climb above its single-engine service ceiling.