Definition
In a multiengine airplane, the highest altitude at which the airplane can maintain level flight with one engine inoperative and the operative engine(s) producing maximum available power. At this altitude, the rate of climb is zero, and the airplane cannot climb any higher on the remaining engine(s).
Plain English
If a multiengine airplane loses an engine, this is the highest altitude it can still hold level on the engine that is still working. Above this altitude, it will slowly drift down no matter what the pilot does.
Context Anchor
Seen in multiengine airplane performance planning, especially when considering engine failure after takeoff, high terrain, hot weather, or heavy loading.
Derivation
‘Absolute’ here comes from the Latin absolutus, meaning ‘complete’ or ‘final.’ In aviation it points to a hard ceiling — the final altitude the airplane can reach in a given configuration. Paired with ‘single engine,’ it means the final altitude reachable when only one engine is producing power.
Why Pilots Care
Determines the practical upper limit of the aircraft's operating envelope and affects route and altitude decisions.
Intuition Check
Do not read “absolute” as “perfect” or “exact.” Here it means the highest possible limit. Do not read “ceiling” as a cloud layer or a room ceiling. Here it means the airplane’s upper performance limit on one engine.
Example Sentence 1
Before crossing the mountains, she checked the single engine absolute ceiling to make sure the airplane could still clear the ridges if one engine failed.
Example Sentence 2
Performance data showed the single engine absolute ceiling was 13,500 feet under standard conditions.