AerodynamicsQuestion 464 of 934

What is spiral instability?

  1. Dihedral effect far exceeds directional stability
  2. Longitudinal stability far exceeds lateral stability
  3. The CG sits too far forward for the airspeed
  4. Directional stability far exceeds dihedral effect
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Correct answer: Directional stability far exceeds dihedral effect

Spiral instability exists when static directional stability is very strong compared with the dihedral effect.

Source: Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), Chapter 5: Aerodynamics of Flight — Spiral Instability, page 117

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Questions last reviewed: 18 October 2026