# Lateral Stability

> Stability around the longitudinal axis (Roll). Dihedral effect.

- **Subject:** 081 — Principles of Flight
- **Section:** 081-04 — Stability
- **Topic code:** 081-04-05
- **Last reviewed:** 2026-04-01
- **Author:** Pablo Asensio Martínez
- **HTML version:** https://pilotsyllabus.com/en/principles-of-flight/stability/static-lateral-stability/

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## Mechanism
When an aircraft rolls, the lift vector tilts and a **Sideslip** begins towards the lower wing (due to gravity).
*   Correct static lateral stability creates a rolling moment that raises the lower wing to restore level flight.

## Stability Contributions
1.  **Dihedral**: Upward angle of wings. When sideslipping, the lower wing has a higher effective Angle of Attack than the upper wing -> More Lift -> Restoring Roll.
2.  **Sweepback**: The lower wing (advancing into the relative wind due to sideslip) presents a greater span/less sweep to the airflow -> More Lift -> Restoring Roll.
3.  **High Wing vs Low Wing**:
    *   **High Wing**: Pendulum stability (fuselage hangs below wing) + Interference effect (fuselage directs airflow up over the wing roots) = Naturally stable.
    *   **Low Wing**: Naturally less stable. Requires more Dihedral.

## Anhedral
Downward angle of wings. Used on high-wing heavy transport aircraft (like C-17, BAe 146) or fighters to **reduce** excess lateral stability and improve maneuverability. Too much stability makes the aircraft hard to turn (Dutch Roll tendency).

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Free study notes from pilotsyllabus.com. Not a substitute for training at an approved ATO.