Inertia coupling

Inertia coupling is a potentially lethal phenomenon of high-speed flight in which the inertia of the heavier fuselage overpowers the aerodynamic stabilizing forces of the wing and empennage. The problem became apparent as single-engine jet fighter aircraft were developed with narrow wingspans, that had relatively low roll inertia relative to the pitch and yaw inertia dominated by the long slender high-density fuselage.