Definition
An angle of attack in which the chord line of the airfoil meets the relative wind from above rather than below, producing a downward (negative) lift force. On a typical wing this occurs when the nose is pitched well below the relative wind, such as in a steep pushover or certain dive entries. On a horizontal stabilizer it is the normal operating condition in level flight, since the tail is designed to produce a downward force.
Plain English
The wing or tail surface is meeting the oncoming air from above instead of below, so instead of pushing up it pushes down.
Context Anchor
Seen in icing discussions, especially when describing how the horizontal tail can operate differently from the main wing.
Derivation
Angle of attack means the angle between the wing's chord line and the oncoming air. 'Negative' here is a geometric sign, not a value judgment — it just means the air is hitting the surface from the opposite side compared to normal positive-lift flight.
Why Pilots Care
Ice can shift the range of angles where lift is produced, requiring pilots to recognize when negative values appear in performance data.
Grounding Statement
Picture the tail meeting the airflow with its front edge slightly lower than its back edge; that is the basic idea of negative AOA.
Intuition Check
Negative does not mean wrong, unsafe, or backward here. It means the angle is measured below zero angle of attack, on the opposite side from a positive AOA.
Example Sentence 1
The horizontal stabilizer normally operates at a negative AOA, producing a downward force that balances the airplane in pitch.
Example Sentence 2
The test data showed lift remained negative until AOA reached positive two degrees.