Definition
A loss of lift on the horizontal tail (tailplane) caused when its angle of attack exceeds the critical angle, most commonly triggered by ice accumulation on the leading edge of the tail. Because the tail produces a downward force to keep the nose up, when the tail stalls that downward force is lost and the nose pitches sharply down. Tailplane stall is typically provoked by extending flaps, which increases the downwash striking the tail and increases the tail's angle of attack.
Plain English
The small wing at the back of the airplane stops working properly, usually because ice has built up on it. When that happens, the nose suddenly drops on its own, often right after the pilot lowers the flaps.
Context Anchor
Seen in discussions of aircraft icing, especially during approach or landing when flaps are being used after flight in icing conditions.
Derivation
“Tailplane” means the plane-like surface at the tail of the aircraft. “Stall” in aerodynamics means airflow has stopped following a lifting surface smoothly; it does not mean the engine has stopped.
Why Pilots Care
An ice-induced tailplane stall produces a violent, uncommanded nose-down pitch that can be difficult to recover from and has caused loss of control in icing conditions.
Grounding Statement
Picture ice on the horizontal tail during approach: when flaps are lowered, the tail may suddenly lose its smooth airflow and the nose may drop.
Intuition Check
Do not read “stall” here as an engine problem. A tailplane stall is an airflow problem on the tail, not an engine stoppage and not the same thing as a main wing stall.
Example Sentence 1
After picking up ice on the descent, the crew delayed full flap extension because of the risk of a tailplane stall on final approach.
Example Sentence 2
To recover from a tailplane stall the pilot reduced the flap setting and applied gentle nose-up pressure once airflow was restored over the tail.