Definition
A condition in which an aircraft, after being disturbed from its trimmed state, neither returns to its original condition nor diverges further from it, but instead remains in the new condition produced by the disturbance.
Plain English
If something nudges the aircraft off its setting, it just stays where the nudge left it. It does not drift back on its own, and it does not keep wandering further away.
Context Anchor
Seen in instrument flying discussions of speed stability, especially when describing how an airplane behaves after a pitch or airspeed change.
Derivation
From Latin neutralis, 'neither one nor the other,' and stabilis, 'standing firm.' The aircraft's response is neither restoring nor diverging, so its stability is 'neither' positive nor negative.
Why Pilots Care
Recognizing neutral stability prevents over-correction during minor speed or attitude changes and supports smooth instrument flight.
Analogy
Think of a ball resting on a flat table. Push it a little and it stops in a new spot. It does not roll back, and it does not roll away.
Grounding Statement
In neutral stability, the airplane accepts the new condition instead of naturally returning to the old one.
Intuition Check
Neutral does not mean automatically safe or well-controlled here. It means the airplane has no natural tendency either to return to the original condition or to move farther away from it.
Example Sentence 1
With neutral stability in pitch, a small bump that lowers the nose leaves the aircraft flying steadily at the new, lower attitude until the pilot corrects it.
Example Sentence 2
The pilot observed neutral stability when the nose attitude remained at the slightly lower pitch after a minor turbulence bump.